29 Questions
What is the defining characteristic of animals belonging to phylum Chordata?
Presence of notochord
Phylum Chordata is divided into three subphyla: Urochordata or Tunicata, Cephalochordata, and __________.
Vertebrata
All vertebrates are chordates but not all chordates are vertebrates.
True
What replaces the notochord in adult vertebrates?
cartilaginous or bony vertebral column
What are the two basic body forms of cnidarians?
polyp and medusa
Which phylum includes sea walnuts or comb jellies?
Ctenophora
Ctenophores exhibit radial symmetry.
True
In Phylum Aschelminthes, the body is circular in _______-section.
cross
What is the basis of animal classification?
Features common to various individuals in relation to the arrangement of cells, body symmetry, nature of coelom, patterns of digestive, circulatory, or reproductive systems.
Match the following examples with their respective phylum:
Physalia, Adamsia, Pennatula = Cnidaria Taenia, Fasciola, Planaria = Platyhelminthes Ascaris, Wuchereria, Ancylostoma = Aschelminthes
Animals with radial symmetry can be divided into two identical halves by any plane passing through the central axis of the body.
False
Which animals exhibit tissue level of organization?
Coelenterates
In triploblastic animals, the developing embryo has ___ germinal layer.
three
Match the following germinal layers with the correct animal classification:
Diploblastic = Coelenterates Triploblastic = Platyhelminthes to chordates
What are the difficulties that you would face in classification of animals if common fundamental features are not taken into account?
Difficulties in distinguishing and categorizing different animal groups.
If you are given a specimen, what are the steps that you would follow to classify it?
Examine its characteristics, compare with known animal classifications, and identify key traits for classification.
How useful is the study of the nature of body cavity and coelom in the classification of animals?
It helps in determining evolutionary relationships and understanding anatomical variations within animal groups.
What is the difference between direct and indirect development?
Direct development involves a gradual growth and maturation process without distinct larval forms, whereas indirect development includes larval stages and metamorphosis.
Distinguish between intracellular and extracellular digestion.
Intracellular digestion occurs within cells through the breakdown of food particles, while extracellular digestion takes place outside cells in a specialized cavity or organ.
What are the peculiar features that you find in parasitic platyhelminthes?
Parasitic platyhelminthes exhibit suckers and hooks to attach to hosts, lack a proper body cavity, and have specialized adaptations for parasitic lifestyles.
What are the reasons that you can think of for the arthropods to constitute the largest group of the animal kingdom?
Arthropods are diverse, adaptable to various environments, have jointed appendages for movement, and exhibit high reproductive capacity.
Water vascular system is the characteristic of which group of the following?
Echinodermata
"All vertebrates are chordates but all chordates are not vertebrates". Justify the statement.
Vertebrates are a subgroup within the chordates that possess a vertebral column, whereas chordates include all animals with a notochord at some stage of their lives, which may or may not develop into vertebrae.
How important is the presence of air bladder in Pisces?
The air bladder in Pisces helps in regulating buoyancy, maintaining stability in water, and controlling the depth at which the fish swims.
What are the modifications that are observed in birds that help them fly?
Birds have lightweight bones, powerful flight muscles, aerodynamic feathers, and unique respiratory systems to support flight.
Could the number of eggs or young ones produced by an oviparous and viviparous mother be equal? Why?
No, the number of offspring produced by oviparous and viviparous mothers cannot be equal because oviparous animals lay eggs externally, while viviparous animals give birth to live young, limiting the potential number of offspring in viviparity.
Segmentation in the body is first observed in which of the following?
Annelida
Match the following:
Operculum = Mollusca Parapodia = Annelida Scales = Reptilia Comb plates = Ctenophora Radula = Mollusca Hairs = Mammalia Choanocytes = Porifera Gill slits = Chordata
Prepare a list of some animals that are found parasitic on human beings.
Examples of parasitic animals that infest humans include lice, tapeworms, hookworms, fleas, and mites.
Study Notes
Animal Kingdom
- The need for classification of animals arises due to the vast diversity of over a million species, which helps in assigning a systematic position to newly described species.
Basis of Classification
- Fundamental features common to various animals, such as:
- Arrangement of cells
- Body symmetry
- Nature of coelom
- Patterns of digestive, circulatory, or reproductive systems
- Are used as the basis of animal classification
Levels of Organisation
- Animals exhibit different levels of organisation, including:
- Cellular level (e.g., sponges)
- Tissue level (e.g., coelenterates)
- Organ level (e.g., platyhelminthes and other higher phyla)
- Organ system level (e.g., annelids, arthropods, molluscs, echinoderms, and chordates)
Symmetry
- Animals can be categorised based on their symmetry, including:
- Asymmetrical (e.g., sponges)
- Radial symmetry (e.g., coelenterates, ctenophores, and echinoderms)
- Bilateral symmetry (e.g., annelids, arthropods, and chordates)
Diploblastic and Triploblastic Organisation
- Animals can be classified based on the number of germinal layers, including:
- Diploblastic (e.g., coelenterates)
- Triploblastic (e.g., platyhelminthes to chordates)
Coelom
- Animals can be classified based on the presence or absence of a coelom, including:
- Coelomates (e.g., annelids, molluscs, arthropods, echinoderms, hemichordates, and chordates)
- Pseudocoelomates (e.g., aschelminthes)
- Acoelomates (e.g., platyhelminthes)
Segmentation
- Some animals exhibit segmentation, including:
- Metameric segmentation (e.g., earthworm)
Notochord
- Animals can be classified based on the presence or absence of a notochord, including:
- Chordates (e.g., animals with a notochord)
- Non-chordates (e.g., animals without a notochord)
Classification of Animals
- The broad classification of Animalia is based on common fundamental features, including:
- Phylum Porifera (e.g., sponges)
- Phylum Coelenterata (e.g., cnidarians)
- Phylum Ctenophora (e.g., sea walnuts or comb jellies)
- Phylum Platyhelminthes (e.g., flatworms)
- Phylum Aschelminthes (e.g., roundworms)
- Phylum Annelida (e.g., segmented worms)
- Phylum Arthropoda (e.g., insects, arachnids, and crustaceans)
- Phylum Mollusca (e.g., molluscs)
Phylum Porifera
- Characteristics of phylum Porifera, including:
- Cellular level of organisation
- Asymmetrical or radial symmetry
- Water transport or canal system
- Skeleton made up of spicules or spongin fibres
- Sexes are not separate
- Reproduction takes place by both asexual and sexual means
Phylum Coelenterata (Cnidaria)
- Characteristics of phylum Coelenterata, including:
- Radial symmetry
- Tissue level of organisation
- Cnidoblasts or cnidocytes present
- Two basic body forms: polyp and medusa
- Alternation of generation (metagenesis)
Phylum Ctenophora
- Characteristics of phylum Ctenophora, including:
- Radial symmetry
- Tissue level of organisation
- Eight external rows of ciliated comb plates
- Bioluminescence
- Sexes are not separate
- Reproduction takes place only by sexual means
Phylum Platyhelminthes
- Characteristics of phylum Platyhelminthes, including:
- Bilateral symmetry
- Triploblastic and acoelomate
- Organ level of organisation
- Hooks and suckers present in parasitic forms
- Specialised cells called flame cells help in osmoregulation and excretion
Phylum Aschelminthes
- Characteristics of phylum Aschelminthes, including:
- Bilateral symmetry
- Triploblastic and pseudocoelomate
- Organ-system level of organisation
- Alimentary canal is complete
- Sexes are separate
- Fertilisation is internal and development may be direct or indirect
Phylum Annelida
- Characteristics of phylum Annelida, including:
- Bilateral symmetry
- Triploblastic and coelomate
- Organ-system level of organisation
- Metamerically segmented
- Longitudinal and circular muscles
- Closed circulatory system
- Nephridia help in osmoregulation and excretion
- Neural system consists of paired ganglia and a double ventral nerve cord
Phylum Arthropoda
- Characteristics of phylum Arthropoda, including:
- Bilateral symmetry
- Triploblastic and coelomate
- Organ-system level of organisation
- Segmented
- Jointed appendages
- Chitinous exoskeleton
- Respiratory organs: gills, book gills, book lungs, or tracheal system
- Circulatory system is of open type
- Sensory organs: antennae, eyes, statocysts, or balancing organs
- Excretion takes place through malpighian tubules
- Mostly dioecious
- Fertilisation is usually internal
- Development may be direct or indirect
Phylum Mollusca
- Characteristics of phylum Mollusca, including:
- Bilateral symmetry
- Triploblastic and coelomate
- Organ-system level of organisation
- Soft, unsegmented body
- Molluscan shell made up of calcium carbonate
- Foot, head, and visceral mass
- Radula (tooth-like structure) for feeding
- Respiratory organs: gills, lungs, or book lungs
- Circulatory system is of open type
- Excretion takes place through nephridia
- Dioecious or monoecious
- Fertilisation is usually internal
- Development may be direct or indirect### Molluscs
- Molluscs are terrestrial or aquatic animals with an organ-system level of organisation
- They are bilaterally symmetrical, triploblastic, and coelomate animals
- Body is covered by a calcareous shell and is unsegmented with a distinct head, muscular foot, and visceral hump
- Soft and spongy layer of skin forms a mantle over the visceral hump
- Space between the hump and the mantle is called the mantle cavity, where feather-like gills are present
- Anterior head region has sensory tentacles
- Mouth contains a file-like rasping organ for feeding, called radula
- Examples: Pila (Apple snail), Pinctada (Pearl oyster), Sepia (Cuttlefish), Loligo (Squid), Octopus (Devil fish)
Echinodermata
- These animals have an endoskeleton of calcareous ossicles, hence the name Echinodermata (Spiny bodied)
- All are marine with an organ-system level of organisation
- Adult echinoderms are radially symmetrical, but larvae are bilaterally symmetrical
- They are triploblastic and coelomate animals
- Digestive system is complete with mouth on the lower (ventral) side and anus on the upper (dorsal) side
- Most distinctive feature is the presence of a water vascular system, which helps in locomotion, capture, and transport of food and respiration
- Examples: Asterias (Star fish), Echinus (Sea urchin), Antedon (Sea lily), Cucumaria (Sea cucumber)
Hemichordata
- Hemichordates have a rudimentary structure in the collar region called stomochord, similar to notochord
- Body is cylindrical and is composed of an anterior proboscis, a collar, and a long trunk
- Circulatory system is of open type
- Respiration takes place through gills
- Excretory organ is proboscis gland
- Examples: Balanoglossus and Saccoglossus
Chordata
- Animals belonging to phylum Chordata are fundamentally characterised by the presence of a notochord, a dorsal hollow nerve cord, and paired pharyngeal gill slits
- They are bilaterally symmetrical, triploblastic, coelomate with an organ-system level of organisation
- They possess a post-anal tail and a closed circulatory system
- Examples: Ascidia, Salpa, Doliolum, Branchiostoma (Amphioxus or Lancelet)
Subphylum Vertebrata
- Vertebrates possess notochord during the embryonic period, but it is replaced by a cartilaginous or bony vertebral column in the adult
- Besides the basic chordate characters, vertebrates have a ventral muscular heart with two, three or four chambers, kidneys for excretion and osmoregulation, and paired appendages which may be fins or limbs
- Examples: Petromyzon (Lamprey), Myxine (Hagfish), Scoliodon (Dog fish), Pristis (Saw fish), Carcharodon (Great white shark)
Class Cyclostomata
- All living members are ectoparasites on some fishes
- They have an elongated body bearing 6-15 pairs of gill slits for respiration
- Body is devoid of scales and paired fins
- Circulation is of closed type
- Examples: Petromyzon (Lamprey) and Myxine (Hagfish)
Class Chondrichthyes
- They are marine animals with a streamlined body and have cartilaginous endoskeleton
- Mouth is located ventrally
- Notochord is persistent throughout life
- Gill slits are separate and without operculum (gill cover)
- Skin is tough, containing minute placoid scales
- Teeth are modified placoid scales which are backwardly directed
- Examples: Scoliodon (Dog fish), Pristis (Saw fish), Carcharodon (Great white shark), Trygon (Sting ray)
Class Osteichthyes
- It includes both marine and fresh water fishes with a bony endoskeleton
- Body is streamlined
- Mouth is mostly terminal
- They have four pairs of gills which are covered by an operculum on each side
- Skin is covered with cycloid/ctenoid scales
- Air bladder is present which regulates buoyancy
- Heart is two-chambered (one auricle and one ventricle)
- Examples: Hippocampus (Sea horse), Catla (Katla), Clarias (Magur), Betta (Fighting fish), Pterophyllum (Angel fish)
Class Amphibia
- Amphibians can live in aquatic as well as terrestrial habitats
- Most of them have two pairs of limbs
- Body is divisible into head and trunk
- Tail may be present in some
- Skin is moist without scales
- The eyes have eyelids
- Respiration is by gills, lungs, and through skin
- Heart is three-chambered (two auricles and one ventricle)
- Examples: Bufo (Toad), Rana (Frog), Hyla (Tree frog), Salamandra (Salamander), Ichthyophis (Limbless amphibia)
Class Reptilia
- The class name refers to their creeping or crawling mode of locomotion
- They are mostly terrestrial animals and their body is covered by dry and cornified skin, epidermal scales or scutes
- They do not have external ear openings
- Tympanum represents ear
- Limbs, when present, are two pairs
- Heart is usually three-chambered, but four-chambered in crocodiles
- Examples: Chelone (Turtle), Testudo (Tortoise), Chameleon (Tree lizard), Crocodilus (Crocodile), Alligator (Alligator), Hemidactylus (Wall lizard), Naja (Cobra), Bangarus (Krait), Vipera (Viper)
Class Aves
- The characteristic features of Aves (birds) are the presence of feathers and most of them can fly except flightless birds
- They possess beak
- Forelimbs are modified into wings
- Hind limbs generally have scales and are modified for walking, swimming or clasping the tree branches
- Skin is dry without glands except the oil gland at the base of the tail
- Endoskeleton is fully ossified (bony) and the long bones are hollow with air cavities (pneumatic)
- Heart is completely four-chambered
- Examples: Corvus (Crow), Columba (Pigeon), Psittacula (Parrot), Struthio (Ostrich), Pavo (Peacock), Aptenodytes (Penguin), Neophron (Vulture)
Class Mammalia
-
They are found in a variety of habitats – polar ice caps, deserts, mountains, forests, grasslands, and dark caves
-
Some of them have adapted to fly or live in water
-
The most unique mammalian characteristic is the presence of milk-producing glands (mammary glands) by which the young ones are nourished
-
They have two pairs of limbs, adapted for walking, running, climbing, burrowing, swimming or flying
-
Skin is unique in possessing hair
-
External ears or pinnae are present
-
Different types of teeth are present in the jaw
-
Heart is four-chambered
-
Examples: Oviparous-O rnithorhynchus (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)### Classification of Animals
-
The classification of animals is based on fundamental features such as level of organization, symmetry, cell organization, coelom, segmentation, notochord, etc.
Characteristics of Different Phyla
- Porifera: multicellular animals with cellular level of organization, characteristic flagellated choanocytes
- Coelenterates: tentacles, bear cnidoblasts, mostly aquatic, sessile or free-floating
- Ctenophores: marine animals with comb plates
- Platyhelminths: flat body, bilateral symmetry, parasitic forms have distinct suckers and hooks
- Aschelminthes: pseudocoelomates, parasitic and non-parasitic roundworms
- Annelids: metamerically segmented animals with a true coelom
- Arthropods: jointed appendages, most abundant group of animals
- Molluscs: soft body surrounded by an external calcareous shell, external skeleton made of chitin
- Echinoderms: spiny skin, water vascular system
- Hemichordates: worm-like marine animals, cylindrical body with proboscis, collar, and trunk
- Chordata: notochord either throughout or during early embryonic life, dorsal, hollow nerve cord, paired pharyngeal gill slits
Characteristics of Vertebrates
- Agnatha: most primitive chordates, ectoparasites on fishes, represented by class Cyclostomata
- Gnathostomata: jaws, two superclasses - Pisces and Tetrapoda
- Pisces: fins for locomotion, classes Chondrichthyes and Osteichthyes
- Chondrichthyes: fishes with cartilaginous endoskeleton, marine
- Tetrapoda: two pairs of limbs, classes Amphibia, Reptilia, Aves, and Mammalia
- Amphibia: adapted to live both on land and water
- Reptilia: dry and cornified skin, limbs absent in snakes
- Aves: warm-blooded, feathers, forelimbs modified into wings for flying
- Mammalia: presence of mammary glands, hairs on the skin, viviparity
This quiz covers the basics of classification and structures of different animal species. Learn about the various forms and characteristics of over a million species of animals.
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