NCERT - ANIMAL KINGDOM - 24

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Questions and Answers

What is the primary purpose of classification in the animal kingdom?

To assign a systematic position to newly described species (correct)

To categorize animals based on their colors

To create a hierarchy among animals based on size

To determine the number of species

All members of the animal kingdom exhibit the same pattern of organization of cells.

False

What is the cellular level of organization exhibited by sponges?

Loose cell aggregates

In coelenterates, the arrangement of cells is more complex and is known as the ______ level of organization.

tissue Signup and view all the answers

Which level of organization is characterized by tissues grouped together to form organs?

Organ level Signup and view all the answers

Match the following levels of organization to their descriptions:

Cellular level = Cells arranged as loose aggregates Tissue level = Cells performing the same function grouped into tissues Organ level = Tissues organized to form organs Organ system level = Organs working together for a specific function Signup and view all the answers

Name two animal groups that exhibit organ system level of organization.

Annelids and Chordates Signup and view all the answers

Only a few species in the animal kingdom demonstrate the organ system level of organization.

False Signup and view all the answers

Which of the following best describes an incomplete digestive system?

Has a single opening that serves as both mouth and anus Signup and view all the answers

All animals exhibit either radial or bilateral symmetry.

False Signup and view all the answers

What type of circulatory system allows blood to directly bathe the cells and tissues?

open type circulatory system Signup and view all the answers

In animals with bilateral symmetry, any plane that passes through the center divides the organism into two identical _____ halves.

identical Signup and view all the answers

Which type of symmetry is displayed by coelenterates and echinoderms?

Radial Signup and view all the answers

Match the animal groups with their corresponding symmetry:

Sponges = Asymmetrical Coelenterates = Radial symmetry Humans = Bilateral symmetry Echinoderms = Radial symmetry Signup and view all the answers

A closed circulatory system has blood that is not contained within blood vessels.

False Signup and view all the answers

What is the main characteristic of a complete digestive system?

It has two openings: mouth and anus. Signup and view all the answers

Which structure is responsible for locomotion in annelids?

Longitudinal and circular muscles Signup and view all the answers

All annelids are monoecious.

False Signup and view all the answers

What is the largest phylum of Animalia?

Arthropoda Signup and view all the answers

Annelids are characterized by their body organization and symmetry.

segmented Signup and view all the answers

Which of the following is NOT a characteristic of arthropods?

Closed circulatory system Signup and view all the answers

Name one example of an annelid.

Nereis, Pheretima, or Hirudinaria Signup and view all the answers

Match the following structures with their respective phyla:

Nephridia = Annelida Chitinous exoskeleton = Arthropoda Dioecious = Nereis Medicinal use = Hirudinaria Signup and view all the answers

The respiratory organs of arthropods include , , and __.

gills, book gills, or lungs, tracheal system Signup and view all the answers

Which characteristic distinguishes the class Cyclostomata from other vertebrate classes?

Sucking mouth without jaws Signup and view all the answers

All members of the class Chondrichthyes have a bony endoskeleton.

False Signup and view all the answers

What type of circulatory system do cyclostomes exhibit?

Closed type Signup and view all the answers

Cyclostomes fail to possess __________ and paired fins.

scales Signup and view all the answers

Which class of vertebrates includes species like Lamprey and Hagfish?

Cyclostomata Signup and view all the answers

Match the following classes with their characteristics:

Cyclostomata = Ectoparasites, no jaws Chondrichthyes = Cartilaginous endoskeleton, separate gill slits Osteichthyes = Bony endoskeleton, typically have scales Amphibia = Metamorphic life cycle, typically aquatic larvae Signup and view all the answers

Cyclostomes migrate to freshwater for spawning.

True Signup and view all the answers

What is the number of gill slits found on cyclostomes?

6-15 pairs Signup and view all the answers

Which of the following features are unique to birds?

Feathers Signup and view all the answers

All birds can fly.

False Signup and view all the answers

What unique feature distinguishes mammals from other animal classes?

Presence of mammary glands Signup and view all the answers

The digestive tract of birds includes additional chambers called the ______ and gizzard.

crop Signup and view all the answers

Which of the following is NOT an example of a mammal?

Penguin Signup and view all the answers

Match the following animal classes with their unique features:

Aves = Feathers and hollow bones Mammalia = Hair and mammary glands Reptilia = Scales and cold-blooded Amphibia = Moist skin and metamorphosis Signup and view all the answers

Birds have a completely four-chambered heart.

True Signup and view all the answers

The forelimbs of birds are modified into ______.

wings Signup and view all the answers

What process do sponges use for sexual reproduction?

Formation of gametes Signup and view all the answers

Cnidarians have a central gastro-vascular cavity with two openings.

False Signup and view all the answers

What is the term for the stinging cells found in cnidarians?

cnidoblasts or cnidocytes Signup and view all the answers

Cnidarians exhibit two basic body forms called and .

polyp, medusa Signup and view all the answers

Which of the following examples is NOT a cnidarian?

Euspongia Signup and view all the answers

Match the following organisms with their respective classifications:

Hydra = Cnidarian - Polyp Aurelia = Cnidarian - Medusa Euspongia = Porifera Pennatula = Cnidarian Signup and view all the answers

Ctenophores have an internal skeleton made of calcium carbonate.

False Signup and view all the answers

What is the main form of locomotion in ctenophores?

Ciliated comb plates Signup and view all the answers

Which of the following animals is an example of a viviparous species?

Macropus (Kangaroo) Signup and view all the answers

The respiratory system of the animals mentioned in the content uses skin for gas exchange.

False Signup and view all the answers

What is the heart structure of the animals described?

Four-chambered Signup and view all the answers

Animals like the common dolphin and blue whale are examples of ______ species.

viviparous Signup and view all the answers

Match the following animal examples with their reproduction type:

Ornithorhynchus = Oviparous Macropus = Viviparous Pteropus = Viviparous Canis = Viviparous Signup and view all the answers

Which feature is NOT a characteristic of the phylum Porifera?

Presence of true tissues Signup and view all the answers

Which type of symmetry is primarily exhibited by organisms in the phylum Cnidaria?

Radial Signup and view all the answers

All mammals are oviparous animals.

False Signup and view all the answers

Which of the following is a characteristic of chordates?

Presence of gill slits Signup and view all the answers

All chordates have a dorsal, hollow, and single central nervous system.

True Signup and view all the answers

What are the two subphyla of chordates often referred to as protochordates?

Urochordata and Cephalochordata Signup and view all the answers

In chordates, the notochord is replaced by a __________ in the adult stage.

vertebral column Signup and view all the answers

Match the following features with either Chordates or Non-chordates:

Notochord present = Chordates Central nervous system ventral = Non-chordates Pharynx with gill slits = Chordates Heart is dorsal = Non-chordates Signup and view all the answers

Which statement correctly describes the subphyla Urochordata and Cephalochordata?

Both are exclusively marine. Signup and view all the answers

Vertebrates retain the notochord throughout their life.

False Signup and view all the answers

Name one example of a member from the subphylum Cephalochordata.

Branchiostoma (Amphioxus or Lancelet) Signup and view all the answers

What is the characteristic feature of the water vascular system?

It is found in Echinodermata Signup and view all the answers

All vertebrates are chordates but all chordates are vertebrates.

True Signup and view all the answers

What modifications are observed in birds that help them fly?

Hollow bones, wings with feathers, a high metabolic rate, and a beak without teeth. Signup and view all the answers

The first segmentation in the body is observed in _____

Annelida Signup and view all the answers

Match the following features with their respective animal groups:

Operculum = Mollusca Parapodia = Annelida Scales = Reptilia Gill slits = Cyclostomata and Chondrichthyes Signup and view all the answers

Which of the following characteristics is not present in the phylum Arthropoda?

Notochord Signup and view all the answers

Echinoderms exhibit bilateral symmetry.

False Signup and view all the answers

What type of symmetry is characteristic of coelenterates?

Radial symmetry Signup and view all the answers

The primary level of organization found in mollusks is the __________ system.

Organ Signup and view all the answers

Match the following phyla with their distinctive characteristics:

Porifera = Flagellated choanocytes Cnidaria = Tentacles with cnidoblasts Ctenophora = Comb plates Platyhelminthes = Flat body with bilateral symmetry Signup and view all the answers

Which of the following animal phyla is characterized by a water vascular system?

Echinodermata Signup and view all the answers

All hemichordates possess a notochord.

False Signup and view all the answers

What is the distinguishing feature of the phylum Chordata?

Notochord Signup and view all the answers

Which level of organization involves cells grouped into functional systems?

Organ system level Signup and view all the answers

All members of the animal kingdom exhibit the organ level of organization.

False Signup and view all the answers

What type of organization do sponges exhibit?

Cellular level of organization Signup and view all the answers

In coelenterates, the cells are arranged in a ______ level of organization.

tissue Signup and view all the answers

Match the following animal groups with their levels of organization:

Sponges = Cellular level Cnidarians = Tissue level Platyhelminthes = Organ level Annelids = Organ system level Signup and view all the answers

What is a primary feature used in the classification of animals?

Body symmetry Signup and view all the answers

Animals in the phylum Chordata exhibit organ level organization.

True Signup and view all the answers

Name one characteristic that distinguishes the organ system level of organization.

Organs are grouped to form functional systems. Signup and view all the answers

What structure is formed on the dorsal side during embryonic development in chordates?

Notochord Signup and view all the answers

Animals that do not have a notochord are known as chordates.

False Signup and view all the answers

What type of symmetry is exhibited by echinoderms during their development stages?

Radial or bilateral symmetry Signup and view all the answers

Sponges have a skeleton made up of or fibers.

spicules, spongin Signup and view all the answers

Match the following terms with their definitions:

Ostia = Minute pores in the body wall of sponges Osculum = Large opening where water exits a sponge Spongocoel = Central cavity in sponges Choanocytes = Collar cells that aid in water transport and feeding Signup and view all the answers

What is the method of digestion that takes place in sponges?

Intracellular digestion Signup and view all the answers

Sponges are known for having separate sexes.

False Signup and view all the answers

The canal system in sponges facilitates food gathering, respiratory exchange, and __________ disposal.

waste Signup and view all the answers

Which of the following phyla exhibits bilateral symmetry?

Chordata Signup and view all the answers

All coelenterates possess a complete digestive system.

False Signup and view all the answers

What is the primary type of symmetry exhibited by echinoderms?

Radial symmetry Signup and view all the answers

Arthropods possess an _______ exoskeleton made of chitin.

external Signup and view all the answers

Match the following phyla with their characteristics:

Porifera = Cellular level of organization, flagellated choanocytes Cnidaria = Tentacles with cnidoblasts Echinodermata = Radial symmetry, water vascular system Hemichordata = Worm-like with proboscis, collar and trunk Signup and view all the answers

Which characteristic is unique to the phylum Mollusca?

Presence of a shell Signup and view all the answers

All animals classified under Chordata possess a notochord during their lifecycle.

True Signup and view all the answers

Name one significant feature that distinguishes echinoderms from other phyla.

Water vascular system Signup and view all the answers

Which of the following is a key distinction between chordates and non-chordates?

Chordates have a dorsal, hollow central nervous system. Signup and view all the answers

All chordates possess a post-anal tail throughout their life.

False Signup and view all the answers

Which characteristic is NOT associated with Cyclostomata?

Has paired fins Signup and view all the answers

Name one example of a member of the subphylum Urochordata.

Ascidia Signup and view all the answers

The skin of Chondrichthyes species is smooth and covered in large scales.

False Signup and view all the answers

In adults, the notochord in vertebrates is replaced by a ______.

vertebral column Signup and view all the answers

What are the two subclasses under the division Gnathostomata?

Pisces and Tetrapoda Signup and view all the answers

Match the following subphyla with their characteristics:

Urochordata = Notochord present only in larval tail Cephalochordata = Notochord persists throughout life Vertebrata = Notochord replaced by vertebral column in adults Signup and view all the answers

All living members of the class Cyclostomata are ______ on some fishes.

ectoparasites Signup and view all the answers

What is the main function of gill slits found in chordates?

For respiration Signup and view all the answers

Cephalochordates are often referred to as protochordates.

True Signup and view all the answers

Match the following classes of vertebrates with their key characteristics:

Cyclostomata = Jawless fish Chondrichthyes = Cartilaginous fish Osteichthyes = Bony fish Amphibia = Ectothermic tetrapods Signup and view all the answers

The central nervous system of non-chordates is and .

ventral, solid Signup and view all the answers

What is the primary function of the paired appendages found in vertebrates?

Locomotion Signup and view all the answers

All members of the class Chondrichthyes have a bony endoskeleton.

False Signup and view all the answers

What happens to cyclostome larvae after metamorphosis?

They return to the ocean. Signup and view all the answers

Which of the following animals is classified as a coelomate?

Annelids Signup and view all the answers

Animals that possess a pseudocoelom have their body cavity lined by mesoderm.

False Signup and view all the answers

What term is used to refer to animals that have three germinal layers?

triploblastic Signup and view all the answers

Cnidarians display _ symmetry and can be classified as _ animals.

radial, diploblastic Signup and view all the answers

Match the following types of animal classifications with their definitions:

Coelomates = Animals with a body cavity lined by mesoderm Pseudocoelomates = Animals with a body cavity not lined by mesoderm Acoelomates = Animals without a body cavity Diploblastic = Animals with two germinal layers Signup and view all the answers

Which type of segmentation is characterized by a serial repetition of organs?

Metameric segmentation Signup and view all the answers

Animals with bilateral symmetry can be divided into mirror-image halves by multiple planes.

False Signup and view all the answers

What is the primarily undifferentiated layer found in diploblastic animals?

mesoglea Signup and view all the answers

What type of fertilization is typically observed in the studied animal groups?

Internal Signup and view all the answers

Molluscs exhibit bilateral symmetry and are classified as triploblastic animals.

True Signup and view all the answers

Name one example of a gregarious pest mentioned in the content.

Locusta Signup and view all the answers

The main respiratory structures found in molluscs are called ______.

gills Signup and view all the answers

Which of the following organisms is classified under the phylum Arthropoda?

Prawn Signup and view all the answers

Match the following examples of arthropods with their characteristics:

Apis = Honey bee Bombyx = Silkworm Scorpion = Arachnid Anopheles = Mosquito Signup and view all the answers

All molluscs are dioecious and exhibit indirect development.

False Signup and view all the answers

What structure in molluscs functions for feeding, often described as a file-like rasping organ?

radula Signup and view all the answers

What is one characteristic that distinguishes amphibians from reptiles?

Amphibians have a three-chambered heart. Signup and view all the answers

Amphibians are warm-blooded animals.

False Signup and view all the answers

Name one example of a reptile.

Crocodile Signup and view all the answers

The common opening for the alimentary canal, urinary, and reproductive tracts in amphibians is called the ______.

cloaca Signup and view all the answers

Which of the following animals are classified as chordates?

Lancelets Signup and view all the answers

Match the following amphibians with their examples:

Bufo = Toad Rana = Frog Hyla = Tree frog Salamandra = Salamander Signup and view all the answers

All animals with a notochord are classified as non-chordates.

False Signup and view all the answers

Which of the following respiratory methods do amphibians NOT use?

Scales Signup and view all the answers

What is the primary structural feature that sets sponges apart from other animal phyla?

Water transport or canal system Signup and view all the answers

Fertilization in amphibians is typically internal.

False Signup and view all the answers

What type of skin covering do reptiles have?

Cornified skin or scales Signup and view all the answers

Sponges reproduce __________, meaning they produce both eggs and sperm.

hermaphroditically Signup and view all the answers

Match the following phyla with their characteristics:

Porifera = Asymmetrical and primitive multicellular animals Echinodermata = Exhibit radial or bilateral symmetry Chordata = Possess a notochord at some stage Cnidaria = Have stinging cells called cnidocytes Signup and view all the answers

What role do choanocytes play in sponges?

Help with water transport and food gathering Signup and view all the answers

Echinoderms are always asymmetrical organisms.

False Signup and view all the answers

What is the cavity called that water enters into through the pores of a sponge?

Spongocoel Signup and view all the answers

Which of the following animals is NOT an example of a viviparous species?

Ornithorhynchus (Platypus) Signup and view all the answers

Mammals have a four-chambered heart.

True Signup and view all the answers

What feature distinguishes mammals from other animal classes?

Presence of mammary glands Signup and view all the answers

The organ system level of organization is demonstrated in and .

Annelida, Chordata Signup and view all the answers

Match the following animal classes with their example species:

Mammalia = Elephas (Elephant) Aves = Panthera leo (Lion) Reptilia = Macaca (Monkey) Amphibia = Rattus (Rat) Signup and view all the answers

What is the primary type of reproduction in mammals?

Viviparous Signup and view all the answers

All members of the phylum Cnidaria have a complete digestive system.

False Signup and view all the answers

Name one example of an oviparous species.

Ornithorhynchus (Platypus) Signup and view all the answers

What level of organization is characterized by the grouping of tissues into organs?

Organ level Signup and view all the answers

The organ system level of organization is only found in a few species of the animal kingdom.

False Signup and view all the answers

What is the primary feature that differentiates sponges from other animal groups in terms of cell organization?

Cellular level of organization Signup and view all the answers

Annelids and Arthropods exhibit the __________ level of organization where organs are formed into functional systems.

organ system Signup and view all the answers

Which of the following characteristics is NOT true about annelids?

They have an exoskeleton. Signup and view all the answers

Match the following animal groups with their respective level of organization:

Sponges = Cellular level Coelenterates = Tissue level Platyhelminthes = Organ level Annelids = Organ system level Signup and view all the answers

All Arthropods have jointed appendages.

True Signup and view all the answers

Which of the following statements is true regarding the arrangement of cells in animal classification?

Annelids demonstrate organ system level organization. Signup and view all the answers

Name one example of a terrestrial annelid.

Earthworm Signup and view all the answers

Arthropods have a body plan divided into three main sections: head, thorax, and ______.

abdomen Signup and view all the answers

The arrangement of cells in coelenterates is less complex than in sponges.

False Signup and view all the answers

Can you name an example of an animal that exhibits the tissue level of organization?

Coelenterate (e.g., jellyfish, sea anemone) Signup and view all the answers

Match the following examples with their respective phyla:

Ascaris = Nematoda Nereis = Annelida Wuchereria = Nematoda Hirudinaria = Annelida Signup and view all the answers

What type of circulatory system is found in arthropods?

Open circulatory system Signup and view all the answers

All aquatic annelids possess lateral appendages called parapodia to aid in swimming.

True Signup and view all the answers

What is the main function of nephridia in annelids?

Osmoregulation and excretion Signup and view all the answers

Which feature is characteristic of cnidarians?

Presence of cnidoblasts Signup and view all the answers

Cnidarians exhibit a central gastro-vascular cavity with two openings.

False Signup and view all the answers

What are the two basic body forms exhibited by cnidarians?

Polyp and medusa Signup and view all the answers

Sponges reproduce asexually by __________.

fragmentation Signup and view all the answers

Match the following examples with their corresponding organism:

Sycon = Freshwater sponge Aurelia = Jellyfish Adamsia = Sea anemone Euspongia = Bath sponge Signup and view all the answers

Which characteristic defines ctenophores?

Presence of ciliated comb plates Signup and view all the answers

What type of body symmetry is exhibited by Platyhelminthes?

Bilateral symmetry Signup and view all the answers

Aschelminthes have a complete digestive system.

True Signup and view all the answers

Ctenophores are primarily freshwater organisms.

False Signup and view all the answers

The stinging cells of cnidarians are called __________.

nematocysts Signup and view all the answers

What type of fertilization occurs in Platyhelminthes?

Internal fertilization Signup and view all the answers

Ctenophores exhibit the ability to emit light known as __________.

bioluminescence Signup and view all the answers

Match the following phyla with their characteristics:

Ctenophora = Bioluminescence Platyhelminthes = Dorso-ventrally flattened body Aschelminthes = Circular cross-section body Echinodermata = Radial symmetry Signup and view all the answers

Which of the following is an example of a Platyhelminthes?

Planaria Signup and view all the answers

Sexes are separate in Ctenophora.

False Signup and view all the answers

What adaptations do parasitic flatworms have to absorb nutrients?

Hooks and suckers Signup and view all the answers

What is the primary characteristic of cartilaginous fishes?

They have a two-chambered heart. Signup and view all the answers

All bony fishes are oviparous and exhibit external fertilization.

True Signup and view all the answers

Name an example of a cartilaginous fish.

Scoliodon Signup and view all the answers

The _____ organ assists in buoyancy regulation for bony fishes.

air bladder Signup and view all the answers

Match the following fish species with their classification:

Scoliodon = Cartilaginous fish Hippocampus = Bony fish Pristis = Cartilaginous fish Clarias = Bony fish Signup and view all the answers

Which of the following is a characteristic of cartilaginous fishes?

They have internal fertilization. Signup and view all the answers

All cartilaginous fishes have electric organs.

False Signup and view all the answers

What type of body temperature regulation do cartilaginous fishes exhibit?

Cold-blooded Signup and view all the answers

What characteristic feature is found in Echinodermata?

Water vascular system Signup and view all the answers

All chordates are vertebrates.

False Signup and view all the answers

List two modifications observed in birds that help them fly.

Hollow bones and lightweight feathers. Signup and view all the answers

The first observation of segmentation in the body occurs in __________.

Annelida Signup and view all the answers

Match the following structures with their corresponding groups:

Operculum = Mollusca Parapodia = Annelida Scales = Reptilia Radula = Mollusca Gill slits = Cyclostomata and Chondrichthyes Signup and view all the answers

Which of the following is a characteristic feature of Echinodermata?

Presence of a water vascular system Signup and view all the answers

All echinoderms exhibit bilateral symmetry in their adult stage.

False Signup and view all the answers

What is the primary function of the stomochord in Hemichordata?

It is similar to a notochord and supports the collar region. Signup and view all the answers

Echinodermata are characterized by having a complete digestive system with the mouth located on the side and the anus on the side.

ventral, dorsal Signup and view all the answers

Match the following examples with their respective phylum:

Asterias = Echinodermata Balanoglossus = Hemichordata Echinus = Echinodermata Saccoglossus = Hemichordata Signup and view all the answers

What type of circulatory system do hemichordates possess?

Open Signup and view all the answers

Hemichordates reproduce through internal fertilization.

False Signup and view all the answers

What is the name of the structure that is absent in echinoderms for excretion?

Excretory system Signup and view all the answers

Which type of animal is classified as having a body cavity lined by mesoderm?

Coelomates Signup and view all the answers

All animals are either coelomates or acoelomates.

False Signup and view all the answers

What is the phenomenon called when the body is divided into segments with a serial repetition of certain organs?

metamerism Signup and view all the answers

Animals in which the developing embryo has a third germinal layer, mesoderm, are called __________ animals.

triploblastic Signup and view all the answers

Match the following types of animals with their corresponding characteristics:

Acoelomates = No body cavity Coelomates = Body cavity lined by mesoderm Pseudocoelomates = Body cavity not lined by mesoderm Diploblastic = Two embryonic layers Signup and view all the answers

Which of the following animal groups is an example of diploblastic organisms?

Coelenterates Signup and view all the answers

Pseudocoelomates have a body cavity that is lined by mesoderm.

False Signup and view all the answers

What layer of tissue is present in between the ectoderm and endoderm in diploblastic animals?

mesoglea Signup and view all the answers

Which of the following types of fish are classified under the class Chondrichthyes?

Great white shark Signup and view all the answers

All bony fishes possess an air bladder.

True Signup and view all the answers

Name one example of a viviparous fish.

Torpedo or any stated species like Scoliodon. Signup and view all the answers

The heart of both cartilaginous and bony fishes is ______-chambered.

two Signup and view all the answers

Match the following fish with their type:

Scoliodon = Cartilaginous fish Hippocampus = Bony fish Pristis = Cartilaginous fish Catla = Bony fish Signup and view all the answers

What mechanism allows many cartilaginous fishes to maintain buoyancy?

Oil-filled liver Signup and view all the answers

The gills of bony fishes are covered by an operculum.

True Signup and view all the answers

Describe the sex differentiation in cartilaginous fishes.

Sexes are separate and males have claspers on pelvic fins. Signup and view all the answers

Which of the following features distinguishes the Mollusca from Arthropoda?

Presence of a hard shell Signup and view all the answers

Echinoderms exhibit bilateral symmetry.

False Signup and view all the answers

What type of symmetry do Hemichordata exhibit?

Bilateral symmetry Signup and view all the answers

The term for the stinging cells found in cnidarians is ______.

cnidoblasts Signup and view all the answers

Match the animal classifications to their characteristics:

Porifera = Cellular level of organization Cnidaria = Tentacles with cnidoblasts Echinodermata = Radial symmetry and water vascular system Annelida = Segmented body plan Signup and view all the answers

What is a key feature of the Chordata phylum?

Presence of a notochord Signup and view all the answers

All animals in the kingdom exhibit either bilateral or radial symmetry.

False Signup and view all the answers

What type of digestive system is characterized by having two openings?

Complete digestive system Signup and view all the answers

Which group of animals is characterized by having a water vascular system?

Echinodermata Signup and view all the answers

All vertebrates are classified as chordates.

True Signup and view all the answers

What adaptations help birds to fly?

Hollow bones, feathers, and a high metabolic rate. Signup and view all the answers

How do sponges reproduce asexually?

Fragmentation Signup and view all the answers

The first observation of segmentation in the animal kingdom is found in ______.

Annelida Signup and view all the answers

Cnidarians have a two-opening digestive system.

False Signup and view all the answers

Match the following structures with their respective animal phyla:

Operculum = Mollusca Parapodia = Annelida Scales = Reptilia Comb plates = Ctenophora Radula = Mollusca Signup and view all the answers

What term is used for the stinging cells found in cnidarians?

cnidocytes Signup and view all the answers

Cnidarians exhibit two basic body forms called and .

polyp, medusa Signup and view all the answers

Which of the following is an example of a fresh water sponge?

Spongilla Signup and view all the answers

Match the following cnidarians with their forms:

Aurelia = Medusa Adamsia = Polyp Hydra = Polyp Physalia = Medusa Signup and view all the answers

What type of symmetry do ctenophores exhibit?

radial symmetry Signup and view all the answers

Ctenophores possess a skeleton made of calcium carbonate.

False Signup and view all the answers

Which term refers to animals with three germinal layers?

Triploblastic Signup and view all the answers

All animals with coelom possess a body cavity lined by mesoderm.

True Signup and view all the answers

What type of body cavity is present in animals that are classified as pseudocoelomates?

Pseudocoelom Signup and view all the answers

Animals that can be divided into identical left and right halves in only one plane exhibit __________ symmetry.

bilateral Signup and view all the answers

Match the animal groups with their respective body cavity classification:

Annelids = Coelomates Aschelminthes = Pseudocoelomates Platyhelminthes = Acoelomates Echinoderms = Coelomates Signup and view all the answers

Which of the following statements about metamerism is true?

It is demonstrated in species like earthworms. Signup and view all the answers

Acoelomates have a body cavity between the gut and the body wall.

False Signup and view all the answers

What is the primary characteristic of diploblastic animals?

They have two embryonic layers: ectoderm and endoderm. Signup and view all the answers

Which of the following structures is NOT found in cartilaginous fishes?

Air bladder Signup and view all the answers

All cartilaginous fishes have internal fertilization.

True Signup and view all the answers

Name one type of organism that belongs to the Class Osteichthyes.

Hippocampus Signup and view all the answers

Cartilaginous fishes display _____ body temperature regulation, meaning they are cold-blooded.

poikilothermous Signup and view all the answers

Match the following fish with their respective characteristics:

Scoliodon = Dog fish Pristis = Saw fish Clarias = Magur Exocoetus = Flying fish Signup and view all the answers

Which of the following characteristics is common to all bony fishes?

Presence of an air bladder Signup and view all the answers

Which class of vertebrates is characterized by a lack of jaws?

Cyclostomata Signup and view all the answers

Both cartilaginous and bony fishes have a two-chambered heart.

True Signup and view all the answers

What is the primary method of fertilization for most bony fishes?

External fertilization Signup and view all the answers

The class Chondrichthyes has a bony endoskeleton.

False Signup and view all the answers

What is a key feature of the skin of Chondrichthyes?

Tough skin containing minute placoid scales. Signup and view all the answers

Cyclostomes exhibit a __________ type of circulation.

closed Signup and view all the answers

Match the following vertebrate classes with their primary characteristic:

Cyclostomata = Jawless and ectoparasitic Chondrichthyes = Cartilaginous skeleton Osteichthyes = Bony skeleton Tetrapoda = Limbs for terrestrial living Signup and view all the answers

Which of the following animals is an example of a cyclostome?

Lamprey Signup and view all the answers

Cyclostomes can survive indefinitely in freshwater.

False Signup and view all the answers

Name one example of a class within the superclass Tetrapoda.

Amphibia, Reptilia, Aves, or Mammals. Signup and view all the answers

Which of the following statements is true regarding ctenophores?

They are characterized by bioluminescence. Signup and view all the answers

Flatworms are exclusively external parasites.

False Signup and view all the answers

What type of body organization do aschelminthes possess?

Organ-system level Signup and view all the answers

Flatworms exhibit symmetry and are in body structure.

bilateral, triploblastic Signup and view all the answers

Which of the following is NOT a characteristic feature of birds?

Milk-producing glands Signup and view all the answers

Match each phylum with its key characteristic:

Ctenophora = Bioluminescence Platyhelminthes = Dorso-ventrally flattened body Aschelminthes = Circular cross-section Cnidaria = Stinging cells Signup and view all the answers

How do flatworms primarily absorb nutrients?

Directly through their body surface Signup and view all the answers

All birds are capable of flight.

False Signup and view all the answers

In aschelminthes, males and females are separate.

True Signup and view all the answers

What are the two additional chambers found in the digestive tract of birds?

crop and gizzard Signup and view all the answers

Mammals possess _______ glands that produce milk for their young.

mammary Signup and view all the answers

Name one example of a flatworm.

Taenia or Fasciola Signup and view all the answers

Match the following animals with their classifications:

Neophron = Bird Macropus = Mammal Hemidactylus = Reptile Naja = Poisonous Snake Signup and view all the answers

Which of the following adaptations can be found in mammals?

Hair Signup and view all the answers

Birds have a two-chambered heart.

False Signup and view all the answers

What physiological characteristic enables birds to maintain a constant body temperature?

warm-blooded (homoiothermous) Signup and view all the answers

Which of the following characteristics is NOT true for chordates?

They have a ventral heart. Signup and view all the answers

Urochordates retain the notochord throughout their life.

False Signup and view all the answers

Name one example of a Cephalochordate.

Branchiostoma Signup and view all the answers

All vertebrates exhibit a __________ during their embryonic stage.

notochord Signup and view all the answers

Match the following subphyla with their characteristics:

Urochordata = Notochord present only in larval stage Cephalochordata = Notochord present throughout life Vertebrata = Notochord replaced by vertebral column in adults Signup and view all the answers

Which statement most accurately describes the central nervous system of chordates?

It is dorsal, hollow, and single. Signup and view all the answers

All chordates possess a post-anal tail.

True Signup and view all the answers

What part of the circulatory system do chordates possess?

Closed circulatory system Signup and view all the answers

Which of the following is a characteristic of cartilaginous fishes?

Two-chambered heart Signup and view all the answers

Osteichthyes are characterized by having a bony endoskeleton.

True Signup and view all the answers

What type of reproduction is most commonly seen in bony fishes?

External fertilization Signup and view all the answers

Cartilaginous fishes include species such as and .

Scoliodon, Pristis Signup and view all the answers

Match the following examples of fish with their classifications:

Hippocampus = Bony fish Trygon = Cartilaginous fish Carcharodon = Cartilaginous fish Catla = Bony fish Signup and view all the answers

Which of these features distinguishes cartilaginous fishes from bony fishes?

Presence of claspers in males Signup and view all the answers

All members of Osteichthyes are viviparous.

False Signup and view all the answers

Bony fishes have ______ which helps in regulating buoyancy.

air bladder Signup and view all the answers

Which of the following groups of animals are characterized by the presence of a notochord at some stage of their life cycle?

Chordates Signup and view all the answers

All arthropods have a hard external skeleton made of chitin.

True Signup and view all the answers

What distinguishes Chondrichthyes from Osteichthyes?

Chondrichthyes have a cartilaginous endoskeleton, while Osteichthyes have a bony endoskeleton. Signup and view all the answers

Echinoderms possess a unique feature called the __________ system.

water vascular Signup and view all the answers

Match the following groups of vertebrates with their characteristics:

Amphibia = Can live both in water and on land Reptilia = Dry, cornified skin Aves = Feathers and warm-blooded Mammalia = Presence of mammary glands and hair Signup and view all the answers

Which of the following groups of animals are considered poikilothermous?

Fishes and Amphibians Signup and view all the answers

All mammals exhibit viviparity.

False Signup and view all the answers

What is a common feature of Agnatha?

They are jawless vertebrates and ectoparasites on fishes. Signup and view all the answers

What type of symmetry is found in Echinodermata depending on their stage?

Radial or bilateral symmetry Signup and view all the answers

All members of the phylum Porifera are known for their symmetry.

False Signup and view all the answers

What structure in sponges allows for the flow of water for respiration and waste removal?

Canal system Signup and view all the answers

Animals that possess a notochord are called ______.

chordates Signup and view all the answers

Match the following classifications with their brief descriptions:

Echinodermata = Animals exhibiting radial symmetry Porifera = Primitive multicellular animals commonly known as sponges Chordata = Animals possessing a notochord Non-chordates = Animals without a notochord Signup and view all the answers

What type of reproductive strategy do sponges utilize?

Hermaphroditic Signup and view all the answers

Sponges have separate sexes for reproduction.

False Signup and view all the answers

What are the supportive structures found in sponges called?

Spicules or spongin fibers Signup and view all the answers

Which of the following features is present in Chordates but absent in Non-Chordates?

Dorsal, hollow, single central nervous system Signup and view all the answers

All vertebrates are chordates, but not all chordates are vertebrates.

True Signup and view all the answers

Provide an example of a member from the subphylum Urochordata.

Ascidia Signup and view all the answers

In Cephalochordata, the notochord extends from head to _____ region.

tail Signup and view all the answers

Match the following subphyla with their notable characteristics:

Which characteristic is NOT associated with Chordates?

Dorsal heart Signup and view all the answers

The notochord in Urochordata is present throughout the organism's life.

False Signup and view all the answers

What type of circulatory system do chordates generally possess?

Closed circulatory system Signup and view all the answers

What type of heart do cartilaginous fishes possess?

Two-chambered Signup and view all the answers

All cartilaginous fishes are viviparous.

False Signup and view all the answers

Name an example of a freshwater bony fish.

Labeo (Rohu) Signup and view all the answers

Cartilaginous fishes lack an __________, so they must swim constantly to avoid sinking.

air bladder Signup and view all the answers

Match the following fish with their classification:

Scoliodon = Cartilaginous fish Hippocampus = Bony fish Carcharodon = Cartilaginous fish Catla = Bony fish Signup and view all the answers

Which characteristic is true for Osteichthyes?

They possess an air bladder. Signup and view all the answers

The pelvic fins of male cartilaginous fishes are modified to bear claspers.

True Signup and view all the answers

What is the term used for animals that cannot regulate their body temperature?

Cold-blooded or poikilothermous Signup and view all the answers

Which of the following is NOT a characteristic feature of Aves?

Mammary glands Signup and view all the answers

All members of the class Aves can fly.

False Signup and view all the answers

Name one adaptation that mammals have developed to thrive in various habitats.

Milk-producing glands Signup and view all the answers

The additional chambers in the digestive tract of birds are known as the ______ and gizzard.

crop Signup and view all the answers

Which of the following statements about mammals is true?

Mammals possess hair on their skin. Signup and view all the answers

Match the following birds with their characteristics:

Struthio = Flightless bird Pavo = Known for its colorful tail Neophron = Scavenger bird Corvus = Highly intelligent bird Signup and view all the answers

The heart of birds is completely three-chambered.

False Signup and view all the answers

What is the primary mode of respiration in birds?

Lungs with air sacs Signup and view all the answers

Which of the following animals is oviparous?

Platypus Signup and view all the answers

All mammals have a three-chambered heart.

False Signup and view all the answers

What is a distinctive feature of coelenterates?

Cnidoblasts Signup and view all the answers

Mammals are characterized as being ______thermous.

homoi Signup and view all the answers

Match the following animals with their type of reproduction:

Kangaroo = Viviparous Platypus = Oviparous Dog = Viviparous Dolphin = Viviparous Signup and view all the answers

Which of the following statements about respiration in mammals is true?

Respiration is performed by lungs. Signup and view all the answers

Sexes in mammals are separate and fertilization is internal.

True Signup and view all the answers

Name one example of a viviparous animal.

Dog Signup and view all the answers

What type of symmetry do echinoderms exhibit?

Radial symmetry Signup and view all the answers

All animals with a notochord are classified under the group called chordates.

True Signup and view all the answers

Name the primary supportive structures found in sponges.

Spicules or spongin fibers Signup and view all the answers

The central cavity in sponges through which water flows is called the ______.

spongocoel Signup and view all the answers

Match the following phyla with their common characteristics:

Porifera = Primitive multicellular animals with cellular level organization Echinodermata = Exhibit radial or bilateral symmetry Chordata = Animals with a notochord Cnidaria = Known for stinging cells called cnidocytes Signup and view all the answers

What is the term for the water transport pathways in sponges?

Canal system Signup and view all the answers

Sponges are characterized by separate sexes.

False Signup and view all the answers

What is the process by which sponges reproduce sexually?

The release of sperm into the water for external fertilization. Signup and view all the answers

Which of the following characteristics applies to cartilaginous fishes?

Two-chambered heart with one auricle and one ventricle Signup and view all the answers

All bony fishes are viviparous.

False Signup and view all the answers

What is the function of the air bladder in bony fishes?

To regulate buoyancy Signup and view all the answers

Cartilaginous fishes, like sharks and rays, are categorized as ______ animals.

cold-blooded Signup and view all the answers

Match the following fishes with their classification:

Scoliodon = Cartilaginous fish Hippocampus = Bony fish Pristis = Cartilaginous fish Catla = Bony fish Signup and view all the answers

Which of the following is a notable feature of male cartilaginous fishes?

Pelvic fins bearing claspers Signup and view all the answers

Both cartilaginous and bony fishes have a four-chambered heart.

False Signup and view all the answers

Name an example of a viviparous fish.

Torpedo Signup and view all the answers

What characteristic distinguishes chordates from non-chordates?

Presence of a dorsal, hollow central nervous system Signup and view all the answers

All chordates possess a vertebral column in their adult form.

False Signup and view all the answers

Name a trait that all vertebrates share during their embryonic period.

Notochord Signup and view all the answers

Members of the subphylum _________ are known as protochordates and are exclusively marine.

Urochordata Signup and view all the answers

What is a common feature of Cephalochordata?

Notochord extends from head to tail region Signup and view all the answers

Match the following subphyla with their examples:

Urochordata = Ascidia Cephalochordata = Branchiostoma Vertebrata = Lamprey Signup and view all the answers

All chordates have three distinct subphyla.

True Signup and view all the answers

What is absent in non-chordates that is present in chordates?

Notochord Signup and view all the answers

Which characteristic is unique to mammals?

Presence of mammary glands Signup and view all the answers

Birds have hollow bones to aid in flight.

True Signup and view all the answers

What are the two additional chambers found in a bird's digestive system?

crop and gizzard Signup and view all the answers

The forelimbs of birds are modified into ______.

wings Signup and view all the answers

Match the following animals with their respective classes:

Ornithorhynchus = Mammalia Struthio = Aves Naja = Reptilia Aptenodytes = Aves Signup and view all the answers

Which of the following is a characteristic of the class Aves?

Feathers and beaks Signup and view all the answers

The heart of birds is only three-chambered.

False Signup and view all the answers

Name one flightless bird.

Ostrich Signup and view all the answers

Which of the following animal phyla exhibits radial symmetry?

Echinodermata Signup and view all the answers

All arthropods possess a complete digestive system.

True Signup and view all the answers

What type of skeleton do mollusks possess?

External skeleton or shell Signup and view all the answers

Cnidarians have stinging cells called ______.

cnidoblasts Signup and view all the answers

Match the following animal phyla with their characteristics:

Arthropoda = Jointed appendages and exoskeleton Mollusca = External skeleton usually present Echinodermata = Radial symmetry and water vascular system Chordata = Notochord and dorsal hollow nerve cord Signup and view all the answers

Which characteristic distinguishes Hemichordata from other phyla?

Proboscis and collar Signup and view all the answers

Annelids exhibit radial symmetry.

False Signup and view all the answers

The __________ level of organization is characterized by the presence of tissues grouped together to form organs.

organ Signup and view all the answers

Which group is characterized by a water vascular system?

Echinodermata Signup and view all the answers

All vertebrates are classified as chordates.

True Signup and view all the answers

Name two modifications observed in birds that assist in flight.

Hollow bones, wing shape Signup and view all the answers

The first observation of segmentation in the body is in __________.

Annelida Signup and view all the answers

Match the following structures with their respective phyla:

Operculum = Mollusca Parapodia = Annelida Radula = Mollusca Gill slits = Chondrichthyes Signup and view all the answers

Which of the following birds is flightless?

Struthio Signup and view all the answers

All birds have the ability to fly.

False Signup and view all the answers

What is the most unique characteristic of mammals?

Presence of mammary glands Signup and view all the answers

The respiratory system of birds includes _____ connected to the lungs.

air sacs Signup and view all the answers

Match the following animal classifications with their examples:

Chelone = Turtle Psittacula = Parrot Aptenodytes = Penguin Neophron = Vulture Signup and view all the answers

Which of the following features is NOT typically found in birds?

Mammary glands Signup and view all the answers

What type of fertilization do birds undergo?

Internal fertilization Signup and view all the answers

Birds have a three-chambered heart.

False Signup and view all the answers

Which of the following features distinguishes chordates from non-chordates?

Dorsal, hollow, single central nervous system Signup and view all the answers

All chordates retain their notochord throughout their lives.

False Signup and view all the answers

Name the three subphyla of Phylum Chordata.

Urochordata, Cephalochordata, Vertebrata Signup and view all the answers

In Urochordata, the notochord is only present in the ______ stage.

larval Signup and view all the answers

Which of the following correctly describes the central nervous system in non-chordates?

Ventral, solid, double Signup and view all the answers

Match the following examples with their subphylum:

Ascidia = Urochordata Branchiostoma = Cephalochordata Lamprey = Vertebrata Salpa = Urochordata Signup and view all the answers

All vertebrates are also classified as chordates.

True Signup and view all the answers

What is the main characteristic of the heart in chordates?

Ventral Signup and view all the answers

Which of the following options correctly describes the reproductive methods of sponges?

Asexually by fragmentation and sexually by the formation of gametes. Signup and view all the answers

Cnidarians exhibit only one body form, either polyp or medusa.

False Signup and view all the answers

What is the name of the stinging cells found in cnidarians?

Cnidoblasts or cnidocytes Signup and view all the answers

Cnidarians have a ____________ cavity with a single opening.

gastro-vascular Signup and view all the answers

Match the following examples with their respective categories:

Aurelia = Medusa Adamsia = Polyp Physalia = Cnidarian Spongilla = Porifera Signup and view all the answers

Which of the following correctly describes the body structure of ctenophores?

Radially symmetrical with eight ciliated comb plates. Signup and view all the answers

Corals, a type of cnidarian, have a skeleton made of calcium carbonate.

True Signup and view all the answers

What type of generation do cnidarians exhibit that involves both asexual polyp and sexual medusa?

Metagenesis Signup and view all the answers

What are the main characteristics of arthropods?

Presence of jointed appendages Signup and view all the answers

Echinoderms have a water vascular system that is their most distinctive feature.

True Signup and view all the answers

Name the two superclasses of Gnathostomata.

Pisces and Tetrapoda Signup and view all the answers

The most primitive chordates are represented by the class ______.

Cyclostomata Signup and view all the answers

Match the following animal classes with their defining features:

Chondrichthyes = Cartilaginous endoskeleton Amphibia = Adapted to live both on land and water Reptilia = Dry, cornified skin Mammalia = Presence of mammary glands Signup and view all the answers

Which of the following statements about mammals is correct?

Mammals possess mammary glands. Signup and view all the answers

All vertebrates possess jaws.

False Signup and view all the answers

What key feature do most chordates share?

Notochord Signup and view all the answers

Study Notes

Levels of Organization

Animals display different levels of cellular organization.
Sponges have cellular level of organization, cells are loosely aggregated.
Coelenterates exhibit tissue level of organization, cells with similar functions are grouped into tissues.
Platyhelminthes and higher phyla show organ level of organization, tissues are grouped together to form organs.
Annelids, Arthropods, Molluscs, Echinoderms, and Chordates have organ system level of organization, organs are associated to form functional systems.
Incomplete digestive system has a single opening for mouth and anus, complete digestive system has two openings, mouth and anus.
Circulatory system can be open or closed.
In an open circulatory system, blood is pumped out of the heart and bathes cells and tissues directly.
In a closed circulatory system, blood is circulated through vessels of varying diameters.

Symmetry

Animals can be categorized based on symmetry.
Sponges are mostly asymmetrical, no plane can divide them into equal halves.
Radial symmetry, any plane passing through the central axis divides the organism into two identical halves.
Coelenterates, ctenophores, and echinoderms have radial symmetry.
Bilateral symmetry, the organism can be divided into two identical halves only by a single plane passing through the central axis.
Most animals have bilateral symmetry, allowing for directional movement and a specialized head end.

Phylum - Annelida

Annelids are segmented worms.
They exhibit organ-system level of organization and bilateral symmetry.
They are triploblastic, having three germ layers.
They have metameric segmentation, their body is divided into segments.
They are coelomate, with a true body cavity.
Possess longitudinal and circular muscles for locomotion.
Aquatic annelids, like Nereis, have parapodia (lateral appendages) for swimming.
Have a closed circulatory system.
Nephridia are excretory organs.
Neural system consists of ganglia connected by nerves to a ventral nerve cord.
Examples include Nereis, Pheretima (earthworm), and Hirudinaria (blood-sucking leech).

Phylum - Arthropoda

The largest phylum in Animalia, including insects.
Over two-thirds of all known species are arthropods.
They exhibit organ-system level of organization and bilateral symmetry.
They are triploblastic, having three germ layers.
Arthropods are segmented and coelomate.
Their body is covered by a chitinous exoskeleton, which provides support and protection.
Consists of head, thorax, and abdomen.
They have jointed appendages (arthros-joint, poda-appendages).
Respiratory organs vary: gills, book gills, book lungs, or tracheal system.
They have an open circulatory system.
Have sensory organs such as antennae, eyes (compound and simple), and statocysts (balancing organs).
Examples include Periplaneta (cockroach), Apis (honey bee), Bombyx (silk moth), and Anopheles (mosquito).

Subphylum - Vertebrata

Possess a ventral muscular heart with two, three, or four chambers.
Have kidneys for excretion and osmoregulation.
Have paired appendages which may be fins or limbs.

Division - Agnatha (Lacking jaws)

Includes cyclostomes.

Division - Gnathostomata (Bearing jaws )

Includes super classes Pisces (bearing fins) and Tetrapoda (bearing limbs).

Class - Cyclostomata

Living members are ectoparasites on fish.
Have an elongated body with 6-15 pairs of gill slits for respiration.
Have a sucking and circular mouth without jaws.
Their body is devoid of scales and paired fins.
Cranium and vertebral column are cartilaginous.
Circulation is closed.
They are marine but migrate to freshwater for spawning.
They die within a few days after spawning.
Their larvae return to the ocean after metamorphosis.
Examples include Petromyzon (lamprey) and Myxine (hagfish).

Class - Chondrichthyes

Marine animals with a streamlined body.
Cartilaginous endoskeleton, notochord persists.
Mouth is located ventrally.
Gill slits are separate without an operculum (gill cover).
Skin is tough with minute placoid scales.
Teeth are modified backwardly-directed placoid scales.
Internal fertilization.
Examples include Scoliodon (dogfish), Pristis (sawfish), Trygon (stingray), and Carcharodon (great white shark).

Class - Osteichthyes

Marine and freshwater fishes.
Have a bony endoskeleton.
Mouth terminal or subterminal, paired fins.
Gill slits covered by an operculum.
Swim bladder is present.
Circulation is closed with a two-chambered heart.
Internal fertilization.
Examples include Exocoetus (flying fish), Hippocampus (sea horse), Labeo (rohu), Catla (katla), and Clarias (magur).

Class - Amphibia

First vertebrates to invade land.
Skin is smooth, moist, and without scales.
Respiration by gills, lungs, and skin.
Circulation is closed with a three-chambered heart.
Cold-blooded (poikilothermous).
Fertilization is external, oviparous, metamorphosis.
Examples include Rana (frog), Bufo (toad), Salamandra (salamander), and Ichthyophis (caecilian).

Class - Reptilia

Cold-blooded (poikilothermous) animals, but body temperature is somewhat regulated.
Skin is dry, covered with scales.
Respiration by lungs only.
Mostly terrestrial, found in warm regions.
Circulation is closed with a three-chambered heart except in crocodiles which have a four-chambered heart.
Fertilization is internal, oviparous.
Examples include Chameleon (tree lizard), Calotes (garden lizard), Crocodilus (crocodile), Testudo (tortoise), and Hemidactylus (wall lizard).

Class - Aves (Birds)

Presence of feathers.
Most can fly except for flightless birds (e.g., Ostrich).
Possess a beak.
Forelimbs are modified into wings.
Hind limbs have scales and are modified for walking, swimming, or clasping branches.
Dry skin without glands except for the oil gland at the base of the tail.
Endoskeleton is fully ossified with hollow long bones (pneumatic).
Digestive tract has crop and gizzard.
Heart is completely four-chambered.
Warm-blooded (homoiothermous), maintain constant body temperature.
Respiration by lungs.
Air sacs connected to lungs supplement respiration.
Sexes are separate.
Internal fertilization, oviparous, direct development.
Examples include Columba (pigeon), Psittacula (parrot), Struthio (ostrich), Pavo (peacock), Aptenodytes (penguin), and Neophron (vulture).

Class - Mammalia

Found in diverse habitats.
Some are adapted for flying or living in water.
Presence of milk-producing mammary glands for nourishing young.
Two pairs of limbs adapted for walking, running, climbing, burrowing, swimming, or flying.
Skin is unique with hair.
Heart is four-chambered.
Warm-blooded (homoiothermous).
Respiration by lungs.
Internal fertilization, viviparous (except for the platypus and echidna which are oviparous), parental care.
Examples include Ornithorhynchus (platypus), Macropus (kangaroo), Pteropus (flying fox), and Balaenoptera (blue whale).

Porifera

Sponges reproduce asexually by fragmentation and sexually by forming gametes.
Fertilization is internal and development includes a larval stage.
Examples include Sycon, Spongilla, and Euspongia.

Coelenterata (Cnidaria)

Aquatic, mostly marine, sessile, or free-swimming animals.
Exhibit radial symmetry.
Name derived from cnidoblasts or cnidocytes, which contain stinging capsules or nematocysts on tentacles and the body.
Cnidocytes are used for anchorage, defense, and capturing prey.
Exhibit tissue level of organization and are diploblastic.
Possess a central gastro-vascular cavity with a single opening, the mouth, located on the hypostome.
Digestion is extracellular and intracellular.
Some cnidarians, e.g., corals, have skeletons composed of calcium carbonate.
Cnidarians exhibit two basic body forms: polyp and medusa.
Polyps are sessile and cylindrical, like Hydra and Adamsia.
Medusae are umbrella-shaped and free-swimming, like Aurelia (jellyfish).
Cnidarians that exist in both forms exhibit alternation of generation (metagenesis) where polyps produce medusae asexually, and medusae form polyps sexually (e.g., Obelia).
Examples include Physalia (Portuguese man-of-war), Adamsia (sea anemone), Pennatula (sea-pen), Gorgonia (sea-fan), and Meandrina (brain coral).

Ctenophora

Commonly known as sea walnuts or comb jellies.
Exclusively marine, radially symmetrical, diploblastic organisms with tissue level of organization.
Body bears eight external rows of ciliated comb plates, which aid in locomotion.

Chordata

Bilaterally symmetrical, triploblastic, coelomate animals with organ-system level of organization.
Possess a post-anal tail and a closed circulatory system.

Chordata vs. Non-chordata

Chordates have a notochord, a dorsal, hollow, and single central nervous system, pharynx perforated by gill slits, a ventral heart, and a post-anal tail.
Non-chordates lack these features.
They have a ventral, solid, and double central nervous system, no gill slits, a dorsal heart (if present), and no post-anal tail.

Subphyla of Chordata

Divided into three subphyla: Urochordata or Tunicata, Cephalochordata, and Vertebrata.
Urochordata and Cephalochordata are often referred to as protochordates and are exclusively marine.
In Urochordata, the notochord is present only in the larval tail.
In Cephalochordata, the notochord extends from head to tail and persists throughout life.
Examples of Urochordata: Ascidia, Salpa, Doliolum.
Examples of Cephalochordata: Branchiostoma (Amphioxus or Lancelet).

Vertebrata

Possess a notochord during the embryonic period.
The notochord is replaced by a cartilaginous or bony vertebral column in the adult.
All vertebrates are chordates, but not all chordates are vertebrates.
Examples: Oviparous - Ornithorhynchus (Platypus). Viviparous - Macropus (Kangaroo), Pteropus (Flying fox), Camelus (Camel), Macaca (Monkey), Rattus (Rat), Canis (Dog), Felis (Cat), Elephas (Elephant), Equus (Horse), Delphinus (Common dolphin), Balaenoptera (Blue whale), Panthera tigris (Tiger), Panthera leo (Lion).

Animal Kingdom Organization

Over a million species of animals have been described.
Animal classification is crucial for assigning a systematic position to newly discovered species.
Animal classification is based on fundamental features like cell arrangement, body symmetry, presence of a coelom, and the organization of digestive, circulatory, and reproductive systems.

Levels of Organization

Cellular level of organization: cells are loosely arranged, as seen in sponges.
Tissue level of organization: cells with similar functions are organized into tissues, as seen in coelenterates.
Organ level of organization: tissues are grouped to form organs, each specialized for a specific function, as seen in flatworms and other higher phyla.
Organ system level of organization: organs work together to form functional systems, each responsible for a specific physiological function, as seen in annelids, arthropods, mollusks, echinoderms, and chordates.

Notochord

Notochord is a rod-like structure formed during embryonic development in some animals.
Chordates possess a notochord.
Non-chordates lack a notochord (e.g., porifera to echinoderms).

Broad Classification of Animalia

Phylum Porifera (Sponges):
- Mostly marine, asymmetrical animals.
- Primitive multicellular with a cellular level of organization.
- Have a water transport system with ostia (pores) for water intake and an osculum for water exit.
- Choanocytes line the canal system, facilitating feeding, respiration, and waste removal.
- Intracellular digestion.
- Skeleton made up of spicules or spongin fibers.
- Hermaphrodite (producing both eggs and sperm).
- Common examples: Sycon, Spongilla, Euspongia.
Phylum Cnidaria (Coelenterates):
- Aquatic, mostly marine.
- Radially symmetrical.
- Have a tissue level of organization.
- Possess tentacles with cnidoblasts (stinging cells).
- Examples: Hydra, Jellyfish, Sea anemone, Coral.
Phylum Ctenophora:
- Marine animals commonly called comb jellies.
- Radially symmetrical.
- Have tissue level of organization.
- Possess comb plates for locomotion.
- Examples: Pleurobrachia, Ctenoplana.
Phylum Platyhelminthes (Flatworms):
- Mostly parasitic, bilaterally symmetrical.
- Have an organ level of organization.
- Possess a dorsoventrally flattened body.
- Examples: Planaria, Liver fluke, Tapeworm.
Phylum Aschelminthes (Roundworms):
- Mostly free-living or parasitic.
- Bilaterally symmetrical.
- Have an organ system level of organization.
- Possess cylindrical, elongated bodies with a pseudocoelom.
- Examples: Ascaris, Ancylostoma, Wuchereria.
Phylum Annelida (Segmented worms):
- Commonly known as segmented worms.
- Bilaterally symmetrical.
- Have an organ system level of organization.
- Possess a segmented body with a closed circulatory system.
- Examples: Earthworm, Leech, Nereis.
Phylum Arthropoda:
- Largest phylum in the animal kingdom.
- Bilaterally symmetrical.
- Have an organ system level of organization.
- Possess jointed appendages, a chitinous exoskeleton, and a well-developed nervous system.
- Divided into classes:
  - Insecta (Insects): Cockroach, butterfly, housefly.
  - Arachnida (Spiders, scorpions, ticks, mites).
  - Crustacea (Crabs, prawn, lobster).
  - Myriapoda (Centipedes, millipedes).
Phylum Mollusca:
- Soft-bodied, bilaterally symmetrical animals.
- Have an organ system level of organization.
- Possess a muscular foot, a mantle, and a shell (usually present).
- Divided into classes:
  - Gastropoda (Snails, slugs).
  - Cephalopoda (Octopus, squid, cuttlefish).
  - Bivalvia (Oysters, mussels, clams).
Phylum Echinodermata:
- Marine animals with a spiny skin.
- Radially symmetrical.
- Have an organ system level of organization.
- Possess a water vascular system for locomotion, feeding, and respiration.
- Examples: Starfish, sea urchin, sea cucumber.
Phylum Hemichordata:
- Worm-like animals with a proboscis, collar, and trunk.
- Bilaterally symmetrical.
- Have an organ system level of organization.
- Possess a notochord-like structure in the proboscis.
- Examples: Balanoglossus, Saccoglossus.
Phylum Chordata:
- Bilaterally symmetrical.
- Have an organ system level of organization.
- Possess a notochord, dorsal hollow nerve cord, gill slits, and a post-anal tail.
- Divided into subphyla:
  - Urochordata: Marine animals with a notochord only in larval tail. Examples: Ascidia, Salpa, Doliolum.
  - Cephalochordata: Marine animals with a notochord extending from head to tail throughout life. Examples: Branchiostoma (Amphioxus or Lancelet).
  - Vertebrata: Animals with a vertebral column replacing the notochord in adults.

Vertebrate Subphylum

Vertebrates are chordates that possess a vertebral column replacing the notochord in adulthood.
Vertebrates have a ventral muscular heart, kidneys for excreting and regulating osmotic balance, and paired appendages.

Vertebrate Classes:

Class Cyclostomata (Jawless fishes):
- Ectoparasites on fishes.
- Elongated body with 6-15 pairs of gill slits.
- Sucking, circular mouth without jaws.
- Lack scales and paired fins.
- Cartilaginous cranium and vertebral column.
- Closed circulatory system.
- Marine but migrate to freshwater for spawning.
- Examples: Lamprey (Petromyzon), Hagfish (Myxine).
Class Chondrichthyes (Cartilaginous fishes):
- Marine animals with streamlined bodies.
- Cartilaginous endoskeleton.
- Ventral mouth.
- Persistent notochord throughout life.
- Separate gill slits without operculum (gill cover).
- Tough skin with placoid scales.
- Teeth are modified placoid scales.
- Examples: Sharks, rays, skates.
Class Osteichthyes (Bony fishes):
- Marine and freshwater animals.
- Bony endoskeleton.
- Operculum covering gill slits.
- Scales of various types.
- Swim bladder for buoyancy.
- Examples: Labeo, Catla, Clarias, Rohu, Exocoetus.
Class Amphibia (Amphibians):
- Live both on land and in water.
- Smooth, moist skin without scales.
- 3-chambered heart.
- Respiration through gills, lungs, and skin.
- Eggs without shells laid in water.
- Examples: Frogs, toads, salamanders.
Class Reptilia (Reptiles):
- Terrestrial animals with dry scaly skin.
- 3-chambered heart (except crocodiles with 4 chambers).
- Respiration through lungs.
- Lay shelled eggs.
- Examples: Lizards, snakes, turtles, crocodiles.
Class Aves (Birds):
- Warm-blooded, feathered animals.
- Forelimbs modified into wings.
- Beak instead of teeth.
- 4-chambered heart.
- Lay hard-shelled eggs.
- Examples: Crow, sparrow, pigeon, ostrich.
Class Mammalia (Mammals):
- Warm-blooded, hairy animals.
- Give birth to live young.
- Possess mammary glands for nourishing young.
- 4-chambered heart.
- Examples: Human, dog, cat, cow, whale.

Fundamental Features for Classification

Level of organization (cellular, tissue, organ, organ system).
Symmetry (asymmetrical, radial, bilateral).
Cell organization (unicellular, multicellular).
Coelom presence or absence.
Segmentation (presence or absence).
Notochord presence or absence.
These features provide valuable insights into the evolutionary relationships and diversity of the animal kingdom.

Animal Classification

The text describes the different levels of organization in animals, covering body symmetry, germ layers, body cavities, segmentation, and the presence or absence of a notochord.
Animals can be classified based on their body symmetry:
Asymmetrical: No specific body pattern, e.g., sponges.
Radial: The body can be divided into equal parts in multiple planes, e.g., jellyfish.
Bilateral: The body can be divided into equal left and right halves in only one plane, e.g., humans, worms.

Germ Layers

Diploblastic: Have two germ layers:
- Ectoderm: Forms the outer layer.
- Endoderm: Forms the inner layer, often lining the gut.
- Mesoglea: A non-cellular layer between the ectoderm and endoderm, e.g., jellyfish.
Triploblastic: Have three germ layers.
- Mesoderm: Forms between the ectoderm and endoderm, contributing to muscle, bone, circulatory systems, etc.

Body Cavities

Coelom: A fluid-filled body cavity, lined by mesoderm. Found in animals like annelids, molluscs, arthropods, echinoderms and chordates.
Pseudocoelom: A body cavity that is not fully lined by mesoderm. Found in aschelminths.
Acoelomate: Animals without any body cavity, e.g., flatworms.

Segmentation

Some animals exhibit metamerism, where the body is divided into segments. Each segment may contain repeated structures.
For example, earthworms have metameric segmentation, and their body shows serial repetition of organs.

Notochord

Chordates: Animals that have a notochord, a rod-like structure that provides support during development.
Non-chordates: Animals without a notochord, e.g., sponges, jellyfish, worms, insects, starfish.

Phylum Porifera (Sponges)

A diverse group of simple multicellular animals.
Mostly asymmetrical.
Cellular level of organization.
Possess a water transport system:
Water enters through pores called ostia into a central cavity (spongocoel) and exits through an opening called the osculum.
Choanocytes or collar cells line the spongocoel and canals, aiding in feeding, respiration, and removal of waste.
Digestion is intracellular.
Skeleton made of spicules or spongin fibers.
Hermaphrodite: Both sexes are found in the same individual.
Excretion through malpighian tubules.
Mostly dioecious (separate sexes).
Mostly oviparous (lay eggs).
Development can be direct or indirect.

Phylum Cnidaria (Jellyfish, Corals, Anemones)

Tissue level of organization.
Radial symmetry.
Diploblastic.
Acoelomate.
Incomplete digestive system with a single opening.
Absent circulatory and respiratory systems.
Cnidoblasts with nematocysts (stinging cells) for defense and capturing prey.

Phylum Ctenophora (Comb Jellies)

Tissue level of organization.
Radial symmetry (adults) but some larval stages show bilateral symmetry.
Diploblastic.
Acoelomate.
Incomplete digestive system with a single opening.
Absent circulatory and respiratory systems.
Comb plates for locomotion.

Phylum Platyhelminthes (Flatworms)

Organ system level of organization.
Bilateral symmetry.
Triploblastic.
Acoelomate.
Incomplete digestive system with a single opening.
Absent circulatory and respiratory systems.
Flat body, often with suckers.

Phylum Aschelminthes (Roundworms)

Organ system level of organization.
Bilateral symmetry.
Triploblastic.
Pseudocoelomate.
Complete digestive system with two openings.
Absent circulatory and respiratory systems.
Often worm-shaped, elongated bodies.

Phylum Annelida (Segmented Worms)

Organ system level of organization.
Bilateral symmetry.
Triploblastic.
Coelomate.
Complete digestive system with two openings.
Closed circulatory system.
Segments divided by septa.
Metamerism: Body divided into segments, each containing repeated structures.
Examples: earthworms, leeches.

Phylum Arthropoda (Insects, Crustaceans, Arachnids)

Organ system level of organization.
Bilateral symmetry.
Triploblastic.
Coelomate.
Complete digestive system with two openings.
Open circulatory system (hemolymph).
Exoskeleton made of chitin.
Jointed appendages and segmented body.
Examples: insects, crabs, spiders, scorpions.

Phylum Mollusca (Molluscs)

Organ system level of organization.
Bilateral symmetry.
Triploblastic.
Coelomate.
Complete digestive system with two openings.
Open circulatory system (hemolymph).
Calcareous shell in many species.
Mantle for respiration and shell formation.
Radula (rasping tongue) for feeding.
Examples: snails, slugs, octopus, squid, clams, oysters.

Phylum Echinodermata (Starfish, Sea Urchins, Sea Cucumbers)

Organ system level of organization.
Radial symmetry in adults, bilateral symmetry in larvae.
Triploblastic.
Coelomate.
Water vascular system for movement and feeding.
Examples: starfish, sea urchins, sea cucumbers.

Phylum Chordata (Vertebrates)

Organ system level of organization.
Bilateral symmetry.
Triploblastic.
Coelomate.
Notochord present at some stage of development.
Dorsal hollow nerve cord.
Pharyngeal slits present at some stage of development.
Post-anal tail present at some stage of development.
Examples: fish, amphibians, reptiles, birds, mammals.

Summarizing the Table

The table focuses on the key features of different animal phyla. Features like symmetry, germ layers, coelom, segmentation, digestive system, circulatory system, respiratory system, and distinctive features are highlighted to differentiate each phylum.

Animal Kingdom

Basis of Classification: Animals exhibit diverse structures and forms. Key features used for classification include:
- Levels of Organization:
  - Cellular: Cells loosely aggregated (e.g., sponges)
  - Tissue: Cells grouped to perform specific functions (e.g., coelenterates)
  - Organ: Tissues grouped to form organs, each specialized for a function (e.g., platyhelminthes)
  - Organ System: Organs working together for specific physiological functions (e.g., annelids, arthropods, molluscs, echinoderms, chordates)
- Symmetry:
  - Radial: Body parts arranged around a central axis (e.g., coelenterates, ctenophores)
  - Bilateral: Body divided into identical halves (e.g., platyhelminthes, annelids, arthropods, chordates)
- Coelom: Body cavity
  - Acoelomate: Lack coelom (e.g., platyhelminthes)
  - Pseudocoelomate: Body cavity not lined by mesoderm (e.g., aschelminthes)
  - Coelomate: Body cavity lined by mesoderm (e.g., annelids, arthropods, molluscs, echinoderms, chordates)
- Digestive, Circulatory, and Reproductive Systems: These systems vary widely across animal groups.

Phylum - Porifera (Sponges)

Features:
- Multicellular, but cells loosely organized (cellular level)
- Sessile, aquatic (mostly marine)
- Body with pores and canals for water circulation
- Filter feeders
- Internal skeleton made of spicules (calcium carbonate or silica)
- Reproduction: Asexual (fragmentation) and sexual (formation of gametes, internal fertilization, indirect development with a larval stage)

Phylum - Coelenterata (Cnidaria)

Features:
- Aquatic (mostly marine)
- Sessile or free-swimming
- Radially symmetrical
- Diploblastic (two germ layers)
- Tentacles with cnidoblasts (stinging cells, nematocysts) for prey capture and defense
- Tissue level of organization
- Gastrovascular cavity with a single opening (mouth on hypostome)
- Extracellular and intracellular digestion
- Some have calcium carbonate skeletons (e.g., corals)
- Two body forms:
  - Polyp: Sessile, cylindrical (e.g., Hydra, Adamsia)
  - Medusa: Free-swimming, umbrella-shaped (e.g., Aurelia)
- Some exhibit alternation of generations (metagenesis)

Phylum - Ctenophora

Features:
- Exclusively marine
- Radially symmetrical
- Diploblastic
- Tissue level of organization
- 8 rows of ciliated comb plates for locomotion
- Extracellular and intracellular digestion
- Bioluminescent (emit light)
- Reproduction: only sexual, external fertilization, indirect development, no separate sexes

Phylum - Platyhelminthes (Flatworms)

Features:
- Dorso-ventrally flattened body
- Mostly endoparasites (found in animals, including humans)
- Bilaterally symmetrical
- Triploblastic (three germ layers)
- Acoelomate (lack body cavity)
- Organ level of organization
- Hooks and suckers in parasitic forms
- Absorb nutrients directly through body surface
- Flame cells for osmoregulation and excretion
- Reproduction: Internal fertilization, development through many larval stages, sexes are not separate
- High regeneration capacity in some (e.g., Planaria)

Phylum - Aschelminthes (Roundworms)

Features:
- Circular in cross-section
- Free-living, aquatic, terrestrial, or parasitic
- Triploblastic
- Pseudocoelomate
- Organ-system level of organization
- Complete digestive tract (mouth to anus) with a muscular pharynx
- Excretory tube for waste removal
- Reproduction: Sexes separate (dioecious), internal fertilization, development direct or indirect, females often longer than males

Phylum - Annelida

Features:
- Aquatic (marine or freshwater) or terrestrial
- Free-living or parasitic
- Organ-system level of organization
- Bilaterally symmetrical
- Triploblastic
- Coelomate
- Segmented body (metameres)
- Longitudinal and circular muscles for locomotion
- Aquatic forms may have lateral appendages (parapodia) for swimming
- Closed circulatory system
- Nephridia for osmoregulation and excretion
- Nervous system: Paired ganglia connected by nerves to a double ventral nerve cord
- Reproduction: Sexual, some are dioecious, some are monoecious

Phylum - Arthropoda (Largest phylum)

Features:
- Over two-thirds of known species are arthropods
- Organ-system level of organization
- Bilaterally symmetrical
- Triploblastic
- Segmented body (head, thorax, abdomen)
- Coelomate
- Chitinous exoskeleton (molting required for growth)
- Jointed appendages
- Respiration: Gills (aquatic), book lungs or tracheal system (terrestrial)
- Open circulatory system
- Sensory organs: Antennae, compound or simple eyes, statocysts (balance)
- Powerful jaws
- Often predaceous

Phylum - Mollusca

Features:
- Soft-bodied, mostly aquatic (marine or freshwater)
- Organ-system level of organization
- Bilaterally symmetrical (except for some gastropods)
- Triploblastic
- Coelomate
- Body: - Muscular foot for locomotion - Visceral mass containing internal organs - Mantle (outer fold of skin) that may secrete a shell
- Respiration: Gills (aquatic) or lungs (terrestrial)
- Open circulatory system
- Sensory organs: Eyes, tentacles, statocysts
- Reproduction: Sexual, external or internal fertilization, development direct or indirect
- Classes:
  - Gastropoda (snails, slugs)
  - Bivalvia (clams, oysters)
  - Cephalopoda (squids, octopus)

Phylum - Echinodermata

Features:
- Exclusively marine
- Organ-system level of organization
- Radially symmetrical (pentaradial symmetry)
- Triploblastic
- Coelomate
- Spiny skin with a hard, calcareous endoskeleton
- Water vascular system for locomotion, feeding, and gas exchange
- No head or brain, nervous system is decentralized
- Regeneration capacity
- Reproduction: Sexual, external fertilization, indirect development

Phylum - Chordata

Features:
- Organ-system level of organization
- Bilaterally symmetrical
- Triploblastic
- Coelomate
- Possess a notochord at some stage of development
- Dorsal hollow nerve cord
- Pharyngeal slits (for filter feeding in primitive forms)
- Post-anal tail
- Subphyla:
  - Vertebrata (with vertebral column)
  - Tunicata
  - Cephalochordata

Subphylum - Vertebrata

Features:
- Presence of a vertebral column (backbone)
- Well-developed brain enclosed in a skull
- Paired appendages (fins, limbs)
- Closed circulatory system with a heart
- Reproduction: Mostly sexual, external or internal fertilization
- Classes:
  - Pisces (fishes)
  - Amphibia (frogs, toads, salamanders)
  - Reptilia (lizards, snakes, turtles, crocodiles)
  - Aves (birds)
  - Mammalia (mammals)

Class - Pisces (Fishes)

Features:
- Aquatic, mostly marine
- Streamlined body
- Gills for respiration
- Fins for locomotion and balance
- Scales
- Cold-blooded (poikilothermic)
- Internal or external fertilization
- Two classes:
  - Cartilaginous fishes (Chondrichthyes)
  - Bony fishes (Osteichthyes)

Class - Chondrichthyes (Cartilaginous Fishes)

Features:
- Skeleton made of cartilage
- Mouth on ventral side
- Five to seven gill slits
- Teeth present
- Powerful jaws
- Streamlined body
- Placoid scales
- No air bladder
- Lateral line system for sensing vibrations
- Examples: Sharks, rays, skates

Class - Osteichthyes (Bony Fishes)

Features:
- Skeleton made of bone
- Mouth mostly terminal
- Four pairs of gills covered by an operculum
- Skin covered with cycloid or ctenoid scales
- Air bladder for buoyancy
- Cold-blooded (poikilothermic)
- Mostly oviparous (egg-laying)
- Examples: Salmon, trout, tuna, goldfish

Animal Classification

Diploblastic animals have two embryonic layers: ectoderm and endoderm. Examples include coelenterates.
Triploblastic animals have three embryonic layers: ectoderm, endoderm, and mesoderm. Examples include platyhelminthes to chordates.
Animals possessing a body cavity lined by the mesoderm are called coelomates. Examples include annelids, molluscs, arthropods, echinoderms, hemichordates, and chordates.
Animals possessing a body cavity not lined by the mesoderm, but with scattered mesoderm pouches are called pseudocoelomates. Examples include aschelminthes.
Animals without a body cavity are called acoelomates. Examples include platyhelminthes.
Segmentation is the division of the body internally and externally into segments with repeating organs. This is called metameric segmentation, and the phenomenon is known as metamerism.
Echinoderms are marine animals with a calcareous endoskeleton. They are radially symmetrical as adults but bilaterally symmetrical as larvae. They are triploblastic and coelomate.
Hemichordates are marine animals with a rudimentary structure called a stomochord, similar to a notochord. They are bilaterally symmetrical, triploblastic, and coelomate.
Chordates are animals characterized by the presence of a notochord, a dorsal hollow nerve cord, and paired pharyngeal gill slits.
Vertebrates are members of the Chordata phylum. They have a backbone, also known as a vertebral column, formed from vertebrae.

Characteristics of Phyla

Porifera: Multicellular animals with cellular level of organisation, characterized by flagellated choanocytes.
Cnidaria: Have tentacles and cnidoblasts (stinging cells). Mostly aquatic, sessile or free-floating. Examples include jellyfish and corals.
Ctenophora: Marine animals with comb plates used for locomotion.
Platyhelminthes: Flatworms with bilateral symmetry. Examples include flatworms and tapeworms.
Nematoda: Roundworms with a pseudocoelom.
Annelida: Segmented worms, possess a coelom. Examples include earthworms and leeches.
Arthropoda: Segmented animals with jointed appendages, an exoskeleton of cuticle. Examples include insects, spiders, crabs, and lobsters. They constitute the largest group of the animal kingdom.
Mollusca: Have soft bodies usually enclosed in a shell. Examples include snails, slugs, octopuses, and squids.
Echinodermata: Have water vascular system, radial symmetry as adults, and a calcareous endoskeleton. Examples include starfish, sea urchins, and sea cucumbers.
Hemichordata: Have a proboscis, collar, and trunk. Possess a stomochord, similar to a notochord.
Chordata: Have a notochord, a dorsal, hollow nerve cord, paired pharyngeal gill slits. Examples include fish, amphibians, reptiles, birds, and mammals.

Characteristic Features of Vertebrate Classes

Pisces: Aquatic vertebrates, possessing fins and gills for respiration.
Amphibia: Tetrapods that live both on land and in water.
Reptilia: Amniote animals with a tough, scaly skin.
Aves: Amniote animals with feathers, wings, and a beak.
Mammalia: Warm-blooded vertebrates with mammary glands, hair, and a four-chambered heart.

Other Key Points

The water vascular system is a characteristic of Echinodermata.
Air bladders in fish are important for regulating buoyancy.
Birds have modifications that help them fly, including feathers, wings, and hollow bones.
Segmentation is first observed in Annelida.

Animal Classification

Animals are classified based on several criteria, including body symmetry, germ layers, coelom presence, segmentation, and other characteristics.
Animals exhibiting bilateral symmetry can be divided into two identical halves along a single plane.
Diploblastic animals possess two embryonic layers: ectoderm and endoderm.
Triploblastic animals possess three embryonic layers: ectoderm, mesoderm, and endoderm.
A coelom is a body cavity lined by mesoderm. Animals with a coelom are called coelomates.
Pseudocoelomates possess a body cavity that is not fully lined by mesoderm.
Acoelomates lack a body cavity.
Segmentation refers to the serial repetition of body parts, as seen in annelids and arthropods.

Phylum Porifera

Porifera are commonly called sponges.
They are multicellular organisms and belong to the kingdom Animalia.
They exhibit a cellular level of organization.
They lack tissues and organs.
They are aquatic animals, primarily marine.
They are sessile, meaning they remain attached to a substrate.
Sponges have a porous body with a canal system for water circulation.
They have specialized cells called choanocytes for filter feeding.
Reproduction can be asexual via fragmentation or sexual through gamete formation.

Phylum Coelenterata

Coelenterates, also known as Cnidaria, are aquatic animals, mostly marine.
They can be sessile (attached) or free-swimming.
The name "cnidaria" comes from the presence of cnidoblasts or cnidocytes, stinging cells containing nematocysts.
Cnidocytes are used for defense, capture of prey, and anchorage.
Coelenterates exhibit tissue level organization and are diploblastic.
They possess a central gastrovascular cavity with a single opening that serves as both mouth and anus.
Digestion is extracellular and intracellular.
Some coelenterates, like corals, have a calcium carbonate skeleton.
Two basic body forms are observed: polyp (sessile, cylindrical, e.g., Hydra, Adamsia) and medusa (free-swimming, umbrella-shaped, e.g., Aurelia).
Alternation of generation (metagenesis) occurs in some cnidarians, where polyps produce medusae asexually and medusae form polyps sexually.

Phylum Ctenophora

Ctenophores, commonly known as comb jellies or sea walnuts, are exclusively marine.
They are radially symmetrical, diploblastic, and exhibit tissue level organization.
Their body features eight rows of ciliated comb plates for locomotion.
Digestion is extracellular and intracellular.
They possess a sticky substance called colloblasts for capturing prey.

Subphylum Vertebrata

Vertebrates are a subphylum under the phylum Chordata.
They exhibit advanced features like a dorsal hollow nerve cord, notochord, pharyngeal slits, and a post-anal tail.
Vertebrates further possess a ventral muscular heart, kidneys for excretion and osmoregulation, and paired appendages (fins or limbs).
Vertebrates are divided into two divisions: Agnatha (lacks jaw) and Gnathostomata (bears jaw).

Class Cyclostomata

All living members of the class Cyclostomata are ectoparasites on fishes.
They have an elongated body with 6-15 pairs of gill slits for respiration.
These animals have a sucking and circular mouth without jaws.
They lack scales and paired fins.
Their cranium and vertebral column are cartilaginous.
They have a closed circulatory system.
Cyclostomes are marine but migrate to freshwater for spawning.
They die shortly after spawning, and their larvae return to the ocean after metamorphosis.

Class Chondrichthyes

Chondrichthyes are marine animals with streamlined bodies and cartilaginous endoskeletons.
They have a ventrally positioned mouth.
The notochord persists throughout their life.
Gill slits are separate and lack an operculum (gill cover).
Their skin is tough and contains minute placoid scales.
Teeth are modified placoid scales directed backward.
They possess powerful jaws and are predaceous.
They lack an air bladder and must swim constantly to avoid sinking.
They have a two-chambered heart (one auricle and one ventricle).
Some have electric organs (e.g., Torpedo) and others possess a poison sting (e.g., Trygon).
They are cold-blooded (poikilothermous).
They have separate sexes.
Males have claspers on their pelvic fins.
Fertilization is internal, and many are viviparous (give birth to live young).

Class Osteichthyes

Osteichthyes include both marine and freshwater fishes with bony endoskeletons.
Their body is streamlined.
The mouth is mostly terminal.
They have four pairs of gills covered by an operculum on each side.
Their skin is covered with cycloid/ctenoid scales.
They possess an air bladder for buoyancy regulation.
They have a two-chambered heart (one auricle and one ventricle).
These are cold-blooded animals with separate sexes.
Fertilization is typically external.
They are mostly oviparous (lay eggs).
Development is direct, meaning there is no larval stage.

Phylum Ctenophora

Bioluminescence is a characteristic of ctenophores.
Reproduction is sexual with external fertilization and indirect development.
Examples include Pleurobrachia and Ctenoplana.

Phylum Platyhelminthes

Flattened dorsoventrally, hence called flatworms.
Mostly endoparasites found in animals including humans.
Bilaterally symmetrical, triploblastic, and acoelomate.
Organ-system level of organisation.
Parasitic forms have hooks and suckers.
Absorb nutrients through their body surface.
Flame cells are specialized cells for osmoregulation and excretion.
Sexes are not separate.
Fertilisation is internal with development through numerous larval stages.
High regeneration capacity in some members, like Planaria.
Examples include Taenia (Tapeworm) and Fasciola (Liver fluke).

Phylum Aschelminthes

Circular cross-section, hence called roundworms.
Can be free-living, aquatic, terrestrial, or parasitic in plants and animals.
Organ-system level of body organisation.
Bilaterally symmetrical, triploblastic, and pseudocoelomate.
Complete alimentary canal with a well-developed muscular pharynx.
Excretory tube removes body wastes through the excretory pore.
Dioecious with distinct males and females.
Often females are longer than males.
Fertilisation is internal with direct or indirect development.
Examples include Ascaris (Roundworm), Wuchereria (Filarial worm).

Phylum Annelida

Metamerically segmented animals with a true coelom.
Bilaterally symmetrical, triploblastic, and eucoelomate.
Closed circulatory system with a ventral heart.
Well-developed nervous system with a brain and ventral nerve cord.
Examples include Pheretima (Earthworm), Hirudinaria (Leech).

Phylum Arthropoda

Most abundant group of animals.
Characterized by the presence of jointed appendages.
Bilaterally symmetrical, triploblastic, and eucoelomate.
Exoskeleton made of chitin.
Examples include Periplaneta (Cockroach), Apis (Honey bee).

Phylum Mollusca

Soft body surrounded by an external calcareous shell.
Bilaterally symmetrical, triploblastic, and eucoelomate.
Open circulatory system with a dorsal heart.
Examples include Pila (Apple snail), Sepia (Cuttlefish).

Phylum Echinodermata

Spiny skin.
Water vascular system for locomotion, feeding, and respiration.
Radial symmetry in adults, bilateral symmetry in larvae.
Examples include Asterias (Starfish), Echinus (Sea urchin).

Phylum Hemichordata

Small group of worm-like marine animals.
Cylindrical body with proboscis, collar, and trunk.
Bilaterally symmetrical, triploblastic, and eucoelomate.
Examples include Balanoglossus (Acorn worm).

Phylum Chordata

Possess a notochord either throughout or during early embryonic life.
Dorsal, hollow nerve cord.
Paired pharyngeal gill slits.
Post-anal tail.
Examples include Branchiostoma (Amphioxus), Homo sapiens (Human).

Subphylum Urochordata

Notochord present only in larval tail.
Exclusively marine.
Examples include Ascidia, Salpa, Doliolum.

Subphylum Cephalochordata

Notochord extends from head to tail region and persists throughout life.
Exclusively marine.
Examples include Branchiostoma (Amphioxus).

Subphylum Vertebrata

Notochord present during embryonic period.
Notochord replaced by a cartilaginous or bony vertebral column in adults.
Includes all vertebrates but not all chordates.

Class Cyclostomata

Most primitive chordates.
Ectoparasites on fishes.
Lack jaws.
Examples include Petromyzon (Lamprey), Myxine (Hagfish).

Class Chondrichthyes

Cartilaginous endoskeleton.
Marine.
Fins for locomotion.
Examples include Scoliodon (Dogfish), Pristis (Sawfish).

Class Osteichthyes

Bony endoskeleton.
Marine and freshwater.
Streamlined body.
Air bladder for buoyancy.
Examples include Exocoetus (Flying fish), Hippocampus (Seahorse).

Class Amphibia

Adapted to live on land and water.
Moist skin without scales.
Three-chambered heart.
Examples include Rana (Frog), Bufo (Toad).

Class Reptilia

Dry, cornified skin.
Limbs absent in snakes.
Three-chambered heart.
Examples include Chelone (Turtle), Testudo (Tortoise), Crocodilus (Crocodile).

Class Aves

Presence of feathers.
Forelimbs modified into wings.
Four-chambered heart.
Examples include Corvus (Crow), Columba (Pigeon), Psittacula (Parrot).

Class Mammalia

Presence of mammary glands for nourishing young.
Presence of hair on the skin.
Four-chambered heart.
Examples include Ornithorhynchus (Platypus), Macropus (Kangaroo), Pteropus (Flying fox).

Notochord

Notochord is a rod-like structure found on the dorsal side of some embryonic animals.
Chordates are animals that possess a notochord, while non-chordates do not, including Porifera to Echinoderms.

Animal Classification

Animal kingdom is broadly classified based on fundamental features.
Phylum Porifera: Sponges, primarily marine and asymmetrical with cellular level of organization.
Phylum Porifera: Sponges have a water transport system with pores (ostia) leading to the central cavity (spongocoel) and exiting through the osculum.
Phylum Porifera: Choanocytes line the spongocoel and canals assisting in digestion, respiration and waste removal. Digestion is intracellular.
Phylum Porifera: Skeleton made of spicules or spongin fibers. Sponges are hermaphrodites (possess both male and female reproductive organs).
Phylum Cnidaria: Includes jellyfish, corals, and sea anemones.
Phylum Cnidaria: Radially symmetrical, diploblastic, with a tissue level of organization.
Phylum Cnidaria: Possess cnidoblasts (stinging cells) for defense and capturing prey.
Phylum Ctenophora: Comb jellies.
Phylum Ctenophora: Radially symmetrical, diploblastic, with a tissue level of organization.
Phylum Ctenophora: Possess comb plates for locomotion.
Phylum Platyhelminthes: Flatworms, includes tapeworms and flukes.
Phylum Platyhelminthes: Bilaterally symmetrical, triploblastic, acoelomate, with an organ-system level of organization.
Phylum Platyhelminthes: Possess suckers for attachment.
Phylum Aschelminthes: Roundworms.
Phylum Aschelminthes: Bilaterally symmetrical, triploblastic, pseudocoelomate, with an organ-system level of organization.
Phylum Annelida: Segmented worms, including earthworms and leeches.
Phylum Annelida: Bilaterally symmetrical, triploblastic, coelomate, with an organ-system level of organization.
Phylum Annelida: Possess segmented bodies.
Phylum Arthropoda: Largest animal phylum, including insects, spiders, and crustaceans.
Phylum Arthropoda: Bilaterally symmetrical, triploblastic, coelomate, with an organ-system level of organization.
Phylum Arthropoda: Possess jointed appendages and a chitinous exoskeleton.
Phylum Mollusca: Includes snails, clams, and squids.
Phylum Mollusca: Bilaterally symmetrical, triploblastic, coelomate, with an organ-system level of organization.
Phylum Mollusca: Soft-bodied animals often with a hard shell.
Phylum Echinodermata: Starfish, sea urchins, and sea cucumbers.
Phylum Echinodermata: Radially symmetrical (adults), bilaterally symmetrical (larvae), triploblastic, coelomate, with an organ-system level of organization.
Phylum Echinodermata: Spiny skinned.
Phylum Chordata: Possess notochord, dorsal hollow nerve cord, pharyngeal gill slits, ventral heart, and a post anal tail.

Chordates

Subphyla: Urochordata, Cephalochordata, Vertebrata.
Subphyla Urochordata and Cephalochordata are often referred to as protochordates and are exclusively marine.
Urochordata possesses a notochord only in their larval tail. Example: Ascidia, Salpa, Doliolum
Cephalochordata: Possess a notochord from head to tail throughout their lifetime. Example: Branchiostoma (Amphioxus or Lancelet)

Vertebrates

Subphylum Vertebrata: Possess a notochord during embryonic development.
Vertebrates: Notochord is replaced by a cartilaginous or bony vertebral column in the adult.
All vertebrates are chordates, but not all chordates are vertebrates.

Class Agnatha

Jawless fishes including lampreys and hagfish. Examples: Petromyzon, Myxine
Lack jaws and paired fins.
Possess a cartilaginous skeleton.

Class Chondrichthyes

Cartilaginous fishes including sharks, rays, and skates.
Possess a cartilaginous skeleton.
Have a streamlined body.
Mouth is ventral.
Possess five to seven gill slits.
Skin covered with placoid scales.
Lack an air bladder.
Have to swim constantly to avoid sinking.
Heart is two-chambered (one auricle and one ventricle).
Some have electric organs (Torpedo).
Some possess poison stings (Trygon).
Cold-blooded (poikilothermous).
Sexes are separate.
Males have claspers on pelvic fins for internal fertilization.
Many are viviparous. Examples: Scoliodon (Dog fish), Pristis (Saw fish), Carcharodon (Great white shark), Trygon (Sting ray).

Class Osteichthyes

Bony fishes, including both marine and freshwater fishes.
Possess a bony endoskeleton.
Have a streamlined body.
Mouth is mostly terminal.
Possess four pairs of gills covered by an operculum on each side.
Skin covered with cycloid/ctenoid scales.
Possess an air bladder for buoyancy regulation.
Heart is two-chambered (one auricle and one ventricle).
Cold-blooded animals.
Sexes are separate.
Mostly oviparous with external fertilization.
Development is direct. Examples: Marine – Exocoetus (Flying fish), Hippocampus (Sea horse); Freshwater – Labeo (Rohu), Catla (Katla), Clarias (Magur); Aquarium – Betta (Fighting fish), Pterophyllum (Angel fish).

Class Amphibia

Amphibians, including frogs, toads, salamanders, and newts.
Larva is aquatic and possess gills.
Adult is terrestrial and possesses lungs.
Skin is moist and permeable to water with mucus glands.
Three-chambered heart (two auricles and one ventricle).
Cold-blooded.
External fertilization.
Development is indirect. Examples: Rana (Frog), Bufo (Toad), Hyla (Tree frog), Salamandra (Salamander).
Many exhibit metamorphosis.

Class Reptilia

Reptiles, including lizards, snakes, turtles, and crocodiles.
Possess scales on their skin, and a dry skin.
Possess lungs for respiration.
Mostly oviparous with internal fertilization.
Cold-blooded.
Three-chambered heart (two auricles and one ventricle) except crocodiles which have a four-chambered heart. Examples: Chelone (Turtle), Testudo (Tortoise), Chameleon (Tree lizard), Calotes (Garden lizard), Crocodilus (Crocodile), Alligator (Alligator). Hemidactylus (Wall lizard), Poisonous snakes – Naja (Cobra), Bangarus (Krait), Vipera (Viper).

Class Aves

Birds, characterized by the presence of feathers, and most fly except for flightless birds. Example: Ostrich
Possess a beak.
Forelimbs modified into wings for flying.
Hind limbs are generally scaled for walking, swimming, or grasping branches.
Skin is dry without glands except for an oil gland at the base of the tail.
Endoskeleton is ossified (bony), with hollow long bones filled with air cavities (pneumatic).
Digestive tract has additional chambers, the crop and the gizzard.
Heart is fully four-chambered.
Warm-blooded (homoiothermous).
Respiration via lungs assisted by air sacs.
Internal fertilization.
Oviparous.
Development is direct. Examples: Corvus (Crow), Columba (Pigeon), Psittacula (Parrot), Struthio (Ostrich), Pavo (Peacock), Aptenodytes (Penguin), Neophron (Vulture).

Class Mammalia

Mammals, found in a variety of habitats.
Some mammals fly and some live in water.
Possess mammary glands to provide milk for their offspring.
Possess two pairs of limbs adapted for walking, running, climbing, burrowing, swimming or flying.
Unique skin with hair.
Possess external ears (pinnae).
Possess different types of teeth.
Heart is four-chambered.
Warm-blooded.
Respiration via lungs.
Internal fertilization.
Viviparous with few exceptions.
Development is direct. Examples: Oviparous- Ornithorhynchus (Platypus); Viviparous - Macropus (Kangaroo), Pteropus (Flying fox), Camelus (Camel), Macaca (Monkey), Rattus (Rat), Canis (Dog), Felis (Cat), Elephas (Elephant), Equus (Horse), Delphinus (Common dolphin), Balaenoptera (Blue whale), Panthera tigris (Tiger), Panthera leo (Lion).

Notochord

Notochord is a rod-like structure formed in some animals during embryonic development.
It is derived from mesoderm and located on the dorsal side.
Animals with notochord are called chordates.
Animals without notochord are called non-chordates, examples include porifera and echinoderms.

Classification of Animals

Phylum Porifera
- Commonly known as sponges.
- Mostly marine and asymmetrical.
- Primitive multicellular animals with a cellular level of organisation.
- Have a water transport or canal system.
  - Water enters through ostia (pores) in the body wall.
  - Water flows to the central cavity (spongocoel).
  - Water exits through the osculum.
- Water transport helps with food gathering, respiration, and waste removal.
- Choanocytes line the spongocoel and canals.
- Digestion is intracellular.
- Skeleton is composed of spicules or spongin fibres.
- Hermaphrodite: produce both eggs and sperm.
Phylum Cnidaria
- Mostly marine and have radial symmetry.
- Have tentacles with stinging cnidoblasts.
- Have a gastrovascular cavity.
- Examples include hydra, jellyfish, and sea anemones.
Phylum Ctenophora
- Marine animals with biradial symmetry.
- Have comb-like plates called ctenes.
- Have a gastrovascular cavity.
- Examples include sea walnuts.
Phylum Platyhelminthes
- Commonly called flatworms.
- Bilaterally symmetrical and triploblastic.
- Have a flattened body.
- Examples include planaria, liver fluke, and tapeworm.
Phylum Aschelminthes
- Commonly called roundworms.
- Bilaterally symmetrical and triploblastic.
- Have a cylindrical body.
- Examples include Ascaris lumbricoides.
Phylum Annelida
- Segmented worms.
- Bilaterally symmetrical and triploblastic.
- Have a true coelom and a closed circulatory system.
- Examples include earthworm and leech.
Phylum Arthropoda
- Largest phylum in the animal kingdom.
- Bilaterally symmetrical and triploblastic.
- Have a hard exoskeleton made of chitin.
- Have jointed appendages.
- Examples include insects, crustaceans, and arachnids.
Phylum Mollusca
- Soft-bodied animals.
- Bilaterally symmetrical and triploblastic.
- Often have a hard shell.
- Examples include snails, slugs, and octopuses.
Phylum Echinodermata
- Exclusively marine animals.
- Radially symmetrical.
- Have a water vascular system that helps in locomotion, feeding, and gas exchange.
- Examples include starfish, brittle stars, and sea urchins.
Phylum Hemichordata
- Worm-like animals with a proboscis, collar, and trunk.
- Have a notochord-like structure.
- Examples include Balanoglossus.
Phylum Chordata
- Have a notochord at some stage in their life.
- Have a dorsal hollow nerve cord.
- Have pharyngeal gill slits.
- Have a post-anal tail.
Subphylum Urochordata (Tunicata)
- Exclusively marine.
- Notochord present only in larval tail.
- Examples include Ascidia, Salpa, and Doliolum.
Subphylum Cephalochordata
- Exclusively marine.
- Notochord extends from head to tail region.
- Examples include Branchiostoma (Amphioxus or Lancelet).
Subphylum Vertebrata
- Have a vertebral column that replaces the notochord in adults.
- Have a well-developed brain enclosed within a skull.
- Have a closed circulatory system with a heart.
- Have paired appendages.
- Class Pisces (Fishes)
  - Class Chondrichthyes (Cartilaginous fishes)
    - Have a cartilaginous endoskeleton.
    - Have paired fins.
    - Have a two-chambered heart.
    - Examples include sharks, rays, and skates.
  - Class Osteichthyes (Bony fishes)
    - Have a bony endoskeleton.
    - Have paired fins.
    - Have a two-chambered heart.
    - Examples include tuna, salmon, and goldfish.
- Class Amphibia
  - Have smooth, moist skin.
  - Have three-chambered heart.
  - Have external fertilisation.
  - Metamorphosis from tadpole to adult.
  - Examples include frogs, toads, and salamanders.
- Class Reptilia
  - Have dry, scaly skin.
  - Have three-chambered heart (except crocodiles which have a four-chambered heart).
  - Have internal fertilisation.
  - Lay eggs.
  - Examples include snakes, lizards, crocodiles, and turtles.
- Class Aves (Birds)
  - Have feathers.
  - Have a beak.
  - Have wings.
  - Have a four-chambered heart.
  - Have internal fertilisation.
  - Lay eggs.
  - Examples include eagles, owls, penguins, and chickens.
- Class Mammalia
  - Have mammary glands.
  - Have hair.
  - Have a four-chambered heart.
  - Have internal fertilisation.
  - Give birth to live young.
  - Examples include humans, dogs, cats, whales, bats, and elephants.

Salient Feature Comparison of Chordates and Non-Chordates

Chordates
- Have a notochord.
- Have a dorsal, hollow, and single nervous system.
- Have pharyngeal gill slits.
- Have a ventral heart.
- Have a post-anal tail.
Non-chordates
- No notochord.
- Have a ventral, solid, and double nervous system.
- No pharyngeal gill slits.
- Have a dorsal heart (if present).
- No post-anal tail.

Summary

Animal kingdom is classified based on levels of organisation, symmetry, cell organisation, coelom, segmentation, and notochord.
Porifera are multicellular animals with cellular level of organisation and have choanocytes.
Coelenterates have tentacles and cnidoblasts, they are mostly aquatic and can be sessile or free-floating.
Ctenophores are marine animals with comb plates.
Platyhelminths have flat bodies and exhibit bilateral symmetry.
Arthropoda is the largest phylum in the animal kingdom, they have exoskeletons and jointed appendages.
Mollusca are soft-bodied animals with hard shells.
Echinodermata have radial symmetry and water vascular systems.
Hemichordata are worm-like animals with a proboscis, collar, and trunk.
Chordata have notochords, dorsal hollow nerve cords, pharyngeal gill slits, and post-anal tails.
Vertebrata are chordates that have a vertebral column, a well-developed brain, a closed circulatory system, paired appendages, and internal skeletons.

Phylum Porifera

Sponges are sessile (attached) organisms.
Sponges reproduce asexually through fragmentation and sexually by forming gametes.
Fertilization is internal, and development is indirect, involving a larval stage.
Examples: Sycon (Scypha), Spongilla (Freshwater sponge), and Euspongia (Bath sponge).

Phylum Cnidaria (Coelenterata)

Cnidarians are aquatic, mostly marine, and exhibit radial symmetry.
The name comes from cnidoblasts or cnidocytes, specialized cells containing stinging capsules (nematocysts) used for anchorage, defense, and capturing prey.
These organisms have a tissue level of organization, are diploblastic, and possess a central gastro-vascular cavity with a single opening (mouth) located on the hypostome.
Digestion is both extracellular and intracellular.
Some cnidarians, like corals, have a skeleton made of calcium carbonate.
They exhibit two basic body forms: polyps (sessile and cylindrical, e.g., Hydra, Adamsia) and medusae (umbrella-shaped and free-swimming, e.g., Aurelia, jellyfish).
Cnidarians that exist in both forms exhibit alternation of generations (metagenesis), where polyps reproduce asexually and medusae reproduce sexually (e.g., Obelia).
Examples: Physalia (Portuguese man-of-war), Adamsia (Sea anemone), Pennatula (Sea-pen), Gorgonia (Sea-fan), and Meandrina (Brain coral).

Phylum Ctenophora

Ctenophores are commonly known as sea walnuts or comb jellies.
They are exclusively marine, exhibit radial symmetry, and possess a tissue level of organization.
Each organism has eight external rows of ciliated comb plates that facilitate locomotion.

Phylum Chordata

Chordates possess a notochord, a flexible rod, either throughout or during early embryonic development.
They have a dorsal, hollow nerve cord, paired pharyngeal gill slits, and a post-anal tail.
Phylum Chordata is divided into three subphyla: Urochordata (Tunicata), Cephalochordata, and Vertebrata.

Subphylum Urochordata (Tunicata)

Notochord is present only in the larval tail.
These are exclusively marine.
Examples: Ascidia, Salpa, and Doliolum.

Subphylum Cephalochordata

Notochord extends from head to tail and persists throughout life.
These are exclusively marine.
Example: Branchiostoma (Amphioxus or Lancelet).

Subphylum Vertebrata

Notochord present during embryonic development and replaced by a cartilaginous or bony vertebral column in adults.
Vertebrates are a diverse group that includes fish, amphibians, reptiles, birds, and mammals.

Class Cyclostomata

Most primitive chordates, lacking jaws (Agnatha).
Ectoparasites on fishes.

Class Chondrichthyes

Fishes with a cartilaginous endoskeleton, commonly marine.
Possess fins for locomotion.

Class Osteichthyes

Fishes with a bony endoskeleton.
Possess fins for locomotion.

Class Amphibia

Adapted to live both on land and in water.
Possess two pairs of limbs.

Class Reptilia

Characterized by dry and cornified skin.
Possess two pairs of limbs, except in snakes.
Limbs are adapted for walking, burrowing, or swimming.

Class Aves

Warm-blooded animals with feathers on their bodies.
Forelimbs modified into wings for flying.
Hind limbs adapted for walking, swimming, perching, or clasping.

Class Mammalia

Warm-blooded animals with mammary glands and hairs on their skin.
Possess two pairs of limbs adapted for various functions such as walking, running, climbing, burrowing, swimming, or flying.
Most mammals exhibit viviparity, giving birth to live young.

Other Important Animal Phyla

Platyhelminthes (Flatworms): Flattened bodies, possess a muscular pharynx and digestive system with a single opening.
Aschelminthes (Roundworms): Bilaterally symmetrical, unsegmented, pseudocoelomate.
Annelida (Segmented Worms): Metamerically segmented body with a true coelom.
Arthropoda: Most abundant group of animals characterized by the presence of jointed appendages.
Mollusca: Soft body surrounded by an external calcareous shell.
Echinodermata: Possess a spiny skin and a water vascular system.
Hemichordata: Worm-like marine animals with a cylindrical body, including a proboscis, collar, and trunk.

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Explore the different levels of cellular organization in animals, ranging from sponges to chordates. Understand the concepts of symmetry and the types of digestive and circulatory systems in various animal phyla.

NCERT - ANIMAL KINGDOM - 24 - 25

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Questions and Answers

What is the primary purpose of classification in the animal kingdom?

All members of the animal kingdom exhibit the same pattern of organization of cells.

What is the cellular level of organization exhibited by sponges?

In coelenterates, the arrangement of cells is more complex and is known as the ______ level of organization.

Which level of organization is characterized by tissues grouped together to form organs?

Match the following levels of organization to their descriptions:

Name two animal groups that exhibit organ system level of organization.

Only a few species in the animal kingdom demonstrate the organ system level of organization.

Which of the following best describes an incomplete digestive system?

All animals exhibit either radial or bilateral symmetry.

What type of circulatory system allows blood to directly bathe the cells and tissues?

In animals with bilateral symmetry, any plane that passes through the center divides the organism into two identical _____ halves.

Which type of symmetry is displayed by coelenterates and echinoderms?

Match the animal groups with their corresponding symmetry:

A closed circulatory system has blood that is not contained within blood vessels.

What is the main characteristic of a complete digestive system?

Which structure is responsible for locomotion in annelids?

All annelids are monoecious.

What is the largest phylum of Animalia?

Annelids are characterized by their __________ body organization and __________ symmetry.

Which of the following is NOT a characteristic of arthropods?

Name one example of an annelid.

Match the following structures with their respective phyla:

The respiratory organs of arthropods include __________, __________, and __________.

Which characteristic distinguishes the class Cyclostomata from other vertebrate classes?

All members of the class Chondrichthyes have a bony endoskeleton.

What type of circulatory system do cyclostomes exhibit?

Cyclostomes fail to possess __________ and paired fins.

Which class of vertebrates includes species like Lamprey and Hagfish?

Match the following classes with their characteristics:

Cyclostomes migrate to freshwater for spawning.

What is the number of gill slits found on cyclostomes?

Which of the following features are unique to birds?

All birds can fly.

What unique feature distinguishes mammals from other animal classes?

The digestive tract of birds includes additional chambers called the ______ and gizzard.

Which of the following is NOT an example of a mammal?

Match the following animal classes with their unique features:

Birds have a completely four-chambered heart.

The forelimbs of birds are modified into ______.

What process do sponges use for sexual reproduction?

Cnidarians have a central gastro-vascular cavity with two openings.

What is the term for the stinging cells found in cnidarians?

Cnidarians exhibit two basic body forms called ______ and ______.

Which of the following examples is NOT a cnidarian?

Match the following organisms with their respective classifications:

Ctenophores have an internal skeleton made of calcium carbonate.

What is the main form of locomotion in ctenophores?

Which of the following animals is an example of a viviparous species?

The respiratory system of the animals mentioned in the content uses skin for gas exchange.

What is the heart structure of the animals described?

Animals like the common dolphin and blue whale are examples of ______ species.

Match the following animal examples with their reproduction type:

Which feature is NOT a characteristic of the phylum Porifera?

Which type of symmetry is primarily exhibited by organisms in the phylum Cnidaria?

All mammals are oviparous animals.

Which of the following is a characteristic of chordates?

All chordates have a dorsal, hollow, and single central nervous system.

What are the two subphyla of chordates often referred to as protochordates?

In chordates, the notochord is replaced by a __________ in the adult stage.

Match the following features with either Chordates or Non-chordates:

Which statement correctly describes the subphyla Urochordata and Cephalochordata?

Vertebrates retain the notochord throughout their life.

Name one example of a member from the subphylum Cephalochordata.

What is the characteristic feature of the water vascular system?

All vertebrates are chordates but all chordates are vertebrates.

What modifications are observed in birds that help them fly?

The first segmentation in the body is observed in _____

Match the following features with their respective animal groups:

Which of the following characteristics is not present in the phylum Arthropoda?

Echinoderms exhibit bilateral symmetry.

What type of symmetry is characteristic of coelenterates?

The primary level of organization found in mollusks is the __________ system.

Match the following phyla with their distinctive characteristics:

Which of the following animal phyla is characterized by a water vascular system?

All hemichordates possess a notochord.

Annelids are characterized by their body organization and symmetry.

The respiratory organs of arthropods include , , and __.

Cnidarians exhibit two basic body forms called and .

Sponges have a skeleton made up of or fibers.

The central nervous system of non-chordates is and .

Cnidarians display _ symmetry and can be classified as _ animals.