Podcast
Questions and Answers
What is the primary purpose of classification in the animal kingdom?
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.
All members of the animal kingdom exhibit the same pattern of organization of cells.
False (B)
What is the cellular level of organization exhibited by sponges?
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.
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?
Which level of organization is characterized by tissues grouped together to form organs?
Match the following levels of organization to their descriptions:
Match the following levels of organization to their descriptions:
Name two animal groups that exhibit organ system level of organization.
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.
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?
Which of the following best describes an incomplete digestive system?
All animals exhibit either radial or bilateral symmetry.
All animals exhibit either radial or bilateral symmetry.
What type of circulatory system allows blood to directly bathe the cells and tissues?
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.
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?
Which type of symmetry is displayed by coelenterates and echinoderms?
Match the animal groups with their corresponding symmetry:
Match the animal groups with their corresponding symmetry:
A closed circulatory system has blood that is not contained within blood vessels.
A closed circulatory system has blood that is not contained within blood vessels.
What is the main characteristic of a complete digestive system?
What is the main characteristic of a complete digestive system?
Which structure is responsible for locomotion in annelids?
Which structure is responsible for locomotion in annelids?
All annelids are monoecious.
All annelids are monoecious.
What is the largest phylum of Animalia?
What is the largest phylum of Animalia?
Annelids are characterized by their __________ body organization and __________ symmetry.
Annelids are characterized by their __________ body organization and __________ symmetry.
Which of the following is NOT a characteristic of arthropods?
Which of the following is NOT a characteristic of arthropods?
Name one example of an annelid.
Name one example of an annelid.
Match the following structures with their respective phyla:
Match the following structures with their respective phyla:
The respiratory organs of arthropods include __________, __________, and __________.
The respiratory organs of arthropods include __________, __________, and __________.
Which characteristic distinguishes the class Cyclostomata from other vertebrate classes?
Which characteristic distinguishes the class Cyclostomata from other vertebrate classes?
All members of the class Chondrichthyes have a bony endoskeleton.
All members of the class Chondrichthyes have a bony endoskeleton.
What type of circulatory system do cyclostomes exhibit?
What type of circulatory system do cyclostomes exhibit?
Cyclostomes fail to possess __________ and paired fins.
Cyclostomes fail to possess __________ and paired fins.
Which class of vertebrates includes species like Lamprey and Hagfish?
Which class of vertebrates includes species like Lamprey and Hagfish?
Match the following classes with their characteristics:
Match the following classes with their characteristics:
Cyclostomes migrate to freshwater for spawning.
Cyclostomes migrate to freshwater for spawning.
What is the number of gill slits found on cyclostomes?
What is the number of gill slits found on cyclostomes?
Which of the following features are unique to birds?
Which of the following features are unique to birds?
All birds can fly.
All birds can fly.
What unique feature distinguishes mammals from other animal classes?
What unique feature distinguishes mammals from other animal classes?
The digestive tract of birds includes additional chambers called the ______ and gizzard.
The digestive tract of birds includes additional chambers called the ______ and gizzard.
Which of the following is NOT an example of a mammal?
Which of the following is NOT an example of a mammal?
Match the following animal classes with their unique features:
Match the following animal classes with their unique features:
Birds have a completely four-chambered heart.
Birds have a completely four-chambered heart.
The forelimbs of birds are modified into ______.
The forelimbs of birds are modified into ______.
What process do sponges use for sexual reproduction?
What process do sponges use for sexual reproduction?
Cnidarians have a central gastro-vascular cavity with two openings.
Cnidarians have a central gastro-vascular cavity with two openings.
What is the term for the stinging cells found in cnidarians?
What is the term for the stinging cells found in cnidarians?
Cnidarians exhibit two basic body forms called ______ and ______.
Cnidarians exhibit two basic body forms called ______ and ______.
Which of the following examples is NOT a cnidarian?
Which of the following examples is NOT a cnidarian?
Match the following organisms with their respective classifications:
Match the following organisms with their respective classifications:
Ctenophores have an internal skeleton made of calcium carbonate.
Ctenophores have an internal skeleton made of calcium carbonate.
What is the main form of locomotion in ctenophores?
What is the main form of locomotion in ctenophores?
Which of the following animals is an example of a viviparous species?
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.
The respiratory system of the animals mentioned in the content uses skin for gas exchange.
What is the heart structure of the animals described?
What is the heart structure of the animals described?
Animals like the common dolphin and blue whale are examples of ______ species.
Animals like the common dolphin and blue whale are examples of ______ species.
Match the following animal examples with their reproduction type:
Match the following animal examples with their reproduction type:
Which feature is NOT a characteristic of the phylum Porifera?
Which feature is NOT a characteristic of the phylum Porifera?
Which type of symmetry is primarily exhibited by organisms in the phylum Cnidaria?
Which type of symmetry is primarily exhibited by organisms in the phylum Cnidaria?
All mammals are oviparous animals.
All mammals are oviparous animals.
Which of the following is a characteristic of chordates?
Which of the following is a characteristic of chordates?
All chordates have a dorsal, hollow, and single central nervous system.
All chordates have a dorsal, hollow, and single central nervous system.
What are the two subphyla of chordates often referred to as protochordates?
What are the two subphyla of chordates often referred to as protochordates?
In chordates, the notochord is replaced by a __________ in the adult stage.
In chordates, the notochord is replaced by a __________ in the adult stage.
Match the following features with either Chordates or Non-chordates:
Match the following features with either Chordates or Non-chordates:
Which statement correctly describes the subphyla Urochordata and Cephalochordata?
Which statement correctly describes the subphyla Urochordata and Cephalochordata?
Vertebrates retain the notochord throughout their life.
Vertebrates retain the notochord throughout their life.
Name one example of a member from the subphylum Cephalochordata.
Name one example of a member from the subphylum Cephalochordata.
What is the characteristic feature of the water vascular system?
What is the characteristic feature of the water vascular system?
All vertebrates are chordates but all chordates are vertebrates.
All vertebrates are chordates but all chordates are vertebrates.
What modifications are observed in birds that help them fly?
What modifications are observed in birds that help them fly?
The first segmentation in the body is observed in _____
The first segmentation in the body is observed in _____
Match the following features with their respective animal groups:
Match the following features with their respective animal groups:
Which of the following characteristics is not present in the phylum Arthropoda?
Which of the following characteristics is not present in the phylum Arthropoda?
Echinoderms exhibit bilateral symmetry.
Echinoderms exhibit bilateral symmetry.
What type of symmetry is characteristic of coelenterates?
What type of symmetry is characteristic of coelenterates?
The primary level of organization found in mollusks is the __________ system.
The primary level of organization found in mollusks is the __________ system.
Match the following phyla with their distinctive characteristics:
Match the following phyla with their distinctive characteristics:
Which of the following animal phyla is characterized by a water vascular system?
Which of the following animal phyla is characterized by a water vascular system?
All hemichordates possess a notochord.
All hemichordates possess a notochord.
What is the distinguishing feature of the phylum Chordata?
What is the distinguishing feature of the phylum Chordata?
Which level of organization involves cells grouped into functional systems?
Which level of organization involves cells grouped into functional systems?
All members of the animal kingdom exhibit the organ level of organization.
All members of the animal kingdom exhibit the organ level of organization.
What type of organization do sponges exhibit?
What type of organization do sponges exhibit?
In coelenterates, the cells are arranged in a ______ level of organization.
In coelenterates, the cells are arranged in a ______ level of organization.
Match the following animal groups with their levels of organization:
Match the following animal groups with their levels of organization:
What is a primary feature used in the classification of animals?
What is a primary feature used in the classification of animals?
Animals in the phylum Chordata exhibit organ level organization.
Animals in the phylum Chordata exhibit organ level organization.
Name one characteristic that distinguishes the organ system level of organization.
Name one characteristic that distinguishes the organ system level of organization.
What structure is formed on the dorsal side during embryonic development in chordates?
What structure is formed on the dorsal side during embryonic development in chordates?
Animals that do not have a notochord are known as chordates.
Animals that do not have a notochord are known as chordates.
What type of symmetry is exhibited by echinoderms during their development stages?
What type of symmetry is exhibited by echinoderms during their development stages?
Sponges have a skeleton made up of __________ or __________ fibers.
Sponges have a skeleton made up of __________ or __________ fibers.
Match the following terms with their definitions:
Match the following terms with their definitions:
What is the method of digestion that takes place in sponges?
What is the method of digestion that takes place in sponges?
Sponges are known for having separate sexes.
Sponges are known for having separate sexes.
The canal system in sponges facilitates food gathering, respiratory exchange, and __________ disposal.
The canal system in sponges facilitates food gathering, respiratory exchange, and __________ disposal.
Which of the following phyla exhibits bilateral symmetry?
Which of the following phyla exhibits bilateral symmetry?
All coelenterates possess a complete digestive system.
All coelenterates possess a complete digestive system.
What is the primary type of symmetry exhibited by echinoderms?
What is the primary type of symmetry exhibited by echinoderms?
Arthropods possess an _______ exoskeleton made of chitin.
Arthropods possess an _______ exoskeleton made of chitin.
Match the following phyla with their characteristics:
Match the following phyla with their characteristics:
Which characteristic is unique to the phylum Mollusca?
Which characteristic is unique to the phylum Mollusca?
All animals classified under Chordata possess a notochord during their lifecycle.
All animals classified under Chordata possess a notochord during their lifecycle.
Name one significant feature that distinguishes echinoderms from other phyla.
Name one significant feature that distinguishes echinoderms from other phyla.
Which of the following is a key distinction between chordates and non-chordates?
Which of the following is a key distinction between chordates and non-chordates?
All chordates possess a post-anal tail throughout their life.
All chordates possess a post-anal tail throughout their life.
Which characteristic is NOT associated with Cyclostomata?
Which characteristic is NOT associated with Cyclostomata?
Name one example of a member of the subphylum Urochordata.
Name one example of a member of the subphylum Urochordata.
The skin of Chondrichthyes species is smooth and covered in large scales.
The skin of Chondrichthyes species is smooth and covered in large scales.
In adults, the notochord in vertebrates is replaced by a ______.
In adults, the notochord in vertebrates is replaced by a ______.
What are the two subclasses under the division Gnathostomata?
What are the two subclasses under the division Gnathostomata?
Match the following subphyla with their characteristics:
Match the following subphyla with their characteristics:
All living members of the class Cyclostomata are ______ on some fishes.
All living members of the class Cyclostomata are ______ on some fishes.
What is the main function of gill slits found in chordates?
What is the main function of gill slits found in chordates?
Cephalochordates are often referred to as protochordates.
Cephalochordates are often referred to as protochordates.
Match the following classes of vertebrates with their key characteristics:
Match the following classes of vertebrates with their key characteristics:
The central nervous system of non-chordates is ______ and ______.
The central nervous system of non-chordates is ______ and ______.
What is the primary function of the paired appendages found in vertebrates?
What is the primary function of the paired appendages found in vertebrates?
All members of the class Chondrichthyes have a bony endoskeleton.
All members of the class Chondrichthyes have a bony endoskeleton.
What happens to cyclostome larvae after metamorphosis?
What happens to cyclostome larvae after metamorphosis?
Which of the following animals is classified as a coelomate?
Which of the following animals is classified as a coelomate?
Animals that possess a pseudocoelom have their body cavity lined by mesoderm.
Animals that possess a pseudocoelom have their body cavity lined by mesoderm.
What term is used to refer to animals that have three germinal layers?
What term is used to refer to animals that have three germinal layers?
Cnidarians display _____ symmetry and can be classified as _____ animals.
Cnidarians display _____ symmetry and can be classified as _____ animals.
Match the following types of animal classifications with their definitions:
Match the following types of animal classifications with their definitions:
Which type of segmentation is characterized by a serial repetition of organs?
Which type of segmentation is characterized by a serial repetition of organs?
Animals with bilateral symmetry can be divided into mirror-image halves by multiple planes.
Animals with bilateral symmetry can be divided into mirror-image halves by multiple planes.
What is the primarily undifferentiated layer found in diploblastic animals?
What is the primarily undifferentiated layer found in diploblastic animals?
What type of fertilization is typically observed in the studied animal groups?
What type of fertilization is typically observed in the studied animal groups?
Molluscs exhibit bilateral symmetry and are classified as triploblastic animals.
Molluscs exhibit bilateral symmetry and are classified as triploblastic animals.
Name one example of a gregarious pest mentioned in the content.
Name one example of a gregarious pest mentioned in the content.
The main respiratory structures found in molluscs are called ______.
The main respiratory structures found in molluscs are called ______.
Which of the following organisms is classified under the phylum Arthropoda?
Which of the following organisms is classified under the phylum Arthropoda?
Match the following examples of arthropods with their characteristics:
Match the following examples of arthropods with their characteristics:
All molluscs are dioecious and exhibit indirect development.
All molluscs are dioecious and exhibit indirect development.
What structure in molluscs functions for feeding, often described as a file-like rasping organ?
What structure in molluscs functions for feeding, often described as a file-like rasping organ?
What is one characteristic that distinguishes amphibians from reptiles?
What is one characteristic that distinguishes amphibians from reptiles?
Amphibians are warm-blooded animals.
Amphibians are warm-blooded animals.
Name one example of a reptile.
Name one example of a reptile.
The common opening for the alimentary canal, urinary, and reproductive tracts in amphibians is called the ______.
The common opening for the alimentary canal, urinary, and reproductive tracts in amphibians is called the ______.
Which of the following animals are classified as chordates?
Which of the following animals are classified as chordates?
Match the following amphibians with their examples:
Match the following amphibians with their examples:
All animals with a notochord are classified as non-chordates.
All animals with a notochord are classified as non-chordates.
Which of the following respiratory methods do amphibians NOT use?
Which of the following respiratory methods do amphibians NOT use?
What is the primary structural feature that sets sponges apart from other animal phyla?
What is the primary structural feature that sets sponges apart from other animal phyla?
Fertilization in amphibians is typically internal.
Fertilization in amphibians is typically internal.
What type of skin covering do reptiles have?
What type of skin covering do reptiles have?
Sponges reproduce __________, meaning they produce both eggs and sperm.
Sponges reproduce __________, meaning they produce both eggs and sperm.
Match the following phyla with their characteristics:
Match the following phyla with their characteristics:
What role do choanocytes play in sponges?
What role do choanocytes play in sponges?
Echinoderms are always asymmetrical organisms.
Echinoderms are always asymmetrical organisms.
What is the cavity called that water enters into through the pores of a sponge?
What is the cavity called that water enters into through the pores of a sponge?
Which of the following animals is NOT an example of a viviparous species?
Which of the following animals is NOT an example of a viviparous species?
Mammals have a four-chambered heart.
Mammals have a four-chambered heart.
What feature distinguishes mammals from other animal classes?
What feature distinguishes mammals from other animal classes?
The organ system level of organization is demonstrated in __________ and __________.
The organ system level of organization is demonstrated in __________ and __________.
Match the following animal classes with their example species:
Match the following animal classes with their example species:
What is the primary type of reproduction in mammals?
What is the primary type of reproduction in mammals?
All members of the phylum Cnidaria have a complete digestive system.
All members of the phylum Cnidaria have a complete digestive system.
Name one example of an oviparous species.
Name one example of an oviparous species.
What level of organization is characterized by the grouping of tissues into organs?
What level of organization is characterized by the grouping of tissues into organs?
The organ system level of organization is only found in a few species of the animal kingdom.
The organ system level of organization is only found in a few species of the animal kingdom.
What is the primary feature that differentiates sponges from other animal groups in terms of cell organization?
What is the primary feature that differentiates sponges from other animal groups in terms of cell organization?
Annelids and Arthropods exhibit the __________ level of organization where organs are formed into functional systems.
Annelids and Arthropods exhibit the __________ level of organization where organs are formed into functional systems.
Which of the following characteristics is NOT true about annelids?
Which of the following characteristics is NOT true about annelids?
Match the following animal groups with their respective level of organization:
Match the following animal groups with their respective level of organization:
All Arthropods have jointed appendages.
All Arthropods have jointed appendages.
Which of the following statements is true regarding the arrangement of cells in animal classification?
Which of the following statements is true regarding the arrangement of cells in animal classification?
Name one example of a terrestrial annelid.
Name one example of a terrestrial annelid.
Arthropods have a body plan divided into three main sections: head, thorax, and ______.
Arthropods have a body plan divided into three main sections: head, thorax, and ______.
The arrangement of cells in coelenterates is less complex than in sponges.
The arrangement of cells in coelenterates is less complex than in sponges.
Can you name an example of an animal that exhibits the tissue level of organization?
Can you name an example of an animal that exhibits the tissue level of organization?
Match the following examples with their respective phyla:
Match the following examples with their respective phyla:
What type of circulatory system is found in arthropods?
What type of circulatory system is found in arthropods?
All aquatic annelids possess lateral appendages called parapodia to aid in swimming.
All aquatic annelids possess lateral appendages called parapodia to aid in swimming.
What is the main function of nephridia in annelids?
What is the main function of nephridia in annelids?
Which feature is characteristic of cnidarians?
Which feature is characteristic of cnidarians?
Cnidarians exhibit a central gastro-vascular cavity with two openings.
Cnidarians exhibit a central gastro-vascular cavity with two openings.
What are the two basic body forms exhibited by cnidarians?
What are the two basic body forms exhibited by cnidarians?
Sponges reproduce asexually by __________.
Sponges reproduce asexually by __________.
Match the following examples with their corresponding organism:
Match the following examples with their corresponding organism:
Which characteristic defines ctenophores?
Which characteristic defines ctenophores?
What type of body symmetry is exhibited by Platyhelminthes?
What type of body symmetry is exhibited by Platyhelminthes?
Aschelminthes have a complete digestive system.
Aschelminthes have a complete digestive system.
Ctenophores are primarily freshwater organisms.
Ctenophores are primarily freshwater organisms.
The stinging cells of cnidarians are called __________.
The stinging cells of cnidarians are called __________.
What type of fertilization occurs in Platyhelminthes?
What type of fertilization occurs in Platyhelminthes?
Ctenophores exhibit the ability to emit light known as __________.
Ctenophores exhibit the ability to emit light known as __________.
Match the following phyla with their characteristics:
Match the following phyla with their characteristics:
Which of the following is an example of a Platyhelminthes?
Which of the following is an example of a Platyhelminthes?
Sexes are separate in Ctenophora.
Sexes are separate in Ctenophora.
What adaptations do parasitic flatworms have to absorb nutrients?
What adaptations do parasitic flatworms have to absorb nutrients?
What is the primary characteristic of cartilaginous fishes?
What is the primary characteristic of cartilaginous fishes?
All bony fishes are oviparous and exhibit external fertilization.
All bony fishes are oviparous and exhibit external fertilization.
Name an example of a cartilaginous fish.
Name an example of a cartilaginous fish.
The _____ organ assists in buoyancy regulation for bony fishes.
The _____ organ assists in buoyancy regulation for bony fishes.
Match the following fish species with their classification:
Match the following fish species with their classification:
Which of the following is a characteristic of cartilaginous fishes?
Which of the following is a characteristic of cartilaginous fishes?
All cartilaginous fishes have electric organs.
All cartilaginous fishes have electric organs.
What type of body temperature regulation do cartilaginous fishes exhibit?
What type of body temperature regulation do cartilaginous fishes exhibit?
What characteristic feature is found in Echinodermata?
What characteristic feature is found in Echinodermata?
All chordates are vertebrates.
All chordates are vertebrates.
List two modifications observed in birds that help them fly.
List two modifications observed in birds that help them fly.
The first observation of segmentation in the body occurs in __________.
The first observation of segmentation in the body occurs in __________.
Match the following structures with their corresponding groups:
Match the following structures with their corresponding groups:
Which of the following is a characteristic feature of Echinodermata?
Which of the following is a characteristic feature of Echinodermata?
All echinoderms exhibit bilateral symmetry in their adult stage.
All echinoderms exhibit bilateral symmetry in their adult stage.
What is the primary function of the stomochord in Hemichordata?
What is the primary function of the stomochord in Hemichordata?
Echinodermata are characterized by having a complete digestive system with the mouth located on the ______ side and the anus on the ______ side.
Echinodermata are characterized by having a complete digestive system with the mouth located on the ______ side and the anus on the ______ side.
Match the following examples with their respective phylum:
Match the following examples with their respective phylum:
What type of circulatory system do hemichordates possess?
What type of circulatory system do hemichordates possess?
Hemichordates reproduce through internal fertilization.
Hemichordates reproduce through internal fertilization.
What is the name of the structure that is absent in echinoderms for excretion?
What is the name of the structure that is absent in echinoderms for excretion?
Which type of animal is classified as having a body cavity lined by mesoderm?
Which type of animal is classified as having a body cavity lined by mesoderm?
All animals are either coelomates or acoelomates.
All animals are either coelomates or acoelomates.
What is the phenomenon called when the body is divided into segments with a serial repetition of certain organs?
What is the phenomenon called when the body is divided into segments with a serial repetition of certain organs?
Animals in which the developing embryo has a third germinal layer, mesoderm, are called __________ animals.
Animals in which the developing embryo has a third germinal layer, mesoderm, are called __________ animals.
Match the following types of animals with their corresponding characteristics:
Match the following types of animals with their corresponding characteristics:
Which of the following animal groups is an example of diploblastic organisms?
Which of the following animal groups is an example of diploblastic organisms?
Pseudocoelomates have a body cavity that is lined by mesoderm.
Pseudocoelomates have a body cavity that is lined by mesoderm.
What layer of tissue is present in between the ectoderm and endoderm in diploblastic animals?
What layer of tissue is present in between the ectoderm and endoderm in diploblastic animals?
Which of the following types of fish are classified under the class Chondrichthyes?
Which of the following types of fish are classified under the class Chondrichthyes?
All bony fishes possess an air bladder.
All bony fishes possess an air bladder.
Name one example of a viviparous fish.
Name one example of a viviparous fish.
The heart of both cartilaginous and bony fishes is ______-chambered.
The heart of both cartilaginous and bony fishes is ______-chambered.
Match the following fish with their type:
Match the following fish with their type:
What mechanism allows many cartilaginous fishes to maintain buoyancy?
What mechanism allows many cartilaginous fishes to maintain buoyancy?
The gills of bony fishes are covered by an operculum.
The gills of bony fishes are covered by an operculum.
Describe the sex differentiation in cartilaginous fishes.
Describe the sex differentiation in cartilaginous fishes.
Which of the following features distinguishes the Mollusca from Arthropoda?
Which of the following features distinguishes the Mollusca from Arthropoda?
Echinoderms exhibit bilateral symmetry.
Echinoderms exhibit bilateral symmetry.
What type of symmetry do Hemichordata exhibit?
What type of symmetry do Hemichordata exhibit?
The term for the stinging cells found in cnidarians is ______.
The term for the stinging cells found in cnidarians is ______.
Match the animal classifications to their characteristics:
Match the animal classifications to their characteristics:
What is a key feature of the Chordata phylum?
What is a key feature of the Chordata phylum?
All animals in the kingdom exhibit either bilateral or radial symmetry.
All animals in the kingdom exhibit either bilateral or radial symmetry.
What type of digestive system is characterized by having two openings?
What type of digestive system is characterized by having two openings?
Which group of animals is characterized by having a water vascular system?
Which group of animals is characterized by having a water vascular system?
All vertebrates are classified as chordates.
All vertebrates are classified as chordates.
What adaptations help birds to fly?
What adaptations help birds to fly?
How do sponges reproduce asexually?
How do sponges reproduce asexually?
The first observation of segmentation in the animal kingdom is found in ______.
The first observation of segmentation in the animal kingdom is found in ______.
Cnidarians have a two-opening digestive system.
Cnidarians have a two-opening digestive system.
Match the following structures with their respective animal phyla:
Match the following structures with their respective animal phyla:
What term is used for the stinging cells found in cnidarians?
What term is used for the stinging cells found in cnidarians?
Cnidarians exhibit two basic body forms called ______ and ______.
Cnidarians exhibit two basic body forms called ______ and ______.
Which of the following is an example of a fresh water sponge?
Which of the following is an example of a fresh water sponge?
Match the following cnidarians with their forms:
Match the following cnidarians with their forms:
What type of symmetry do ctenophores exhibit?
What type of symmetry do ctenophores exhibit?
Ctenophores possess a skeleton made of calcium carbonate.
Ctenophores possess a skeleton made of calcium carbonate.
Which term refers to animals with three germinal layers?
Which term refers to animals with three germinal layers?
All animals with coelom possess a body cavity lined by mesoderm.
All animals with coelom possess a body cavity lined by mesoderm.
What type of body cavity is present in animals that are classified as pseudocoelomates?
What type of body cavity is present in animals that are classified as pseudocoelomates?
Animals that can be divided into identical left and right halves in only one plane exhibit __________ symmetry.
Animals that can be divided into identical left and right halves in only one plane exhibit __________ symmetry.
Match the animal groups with their respective body cavity classification:
Match the animal groups with their respective body cavity classification:
Which of the following statements about metamerism is true?
Which of the following statements about metamerism is true?
Acoelomates have a body cavity between the gut and the body wall.
Acoelomates have a body cavity between the gut and the body wall.
What is the primary characteristic of diploblastic animals?
What is the primary characteristic of diploblastic animals?
Which of the following structures is NOT found in cartilaginous fishes?
Which of the following structures is NOT found in cartilaginous fishes?
All cartilaginous fishes have internal fertilization.
All cartilaginous fishes have internal fertilization.
Name one type of organism that belongs to the Class Osteichthyes.
Name one type of organism that belongs to the Class Osteichthyes.
Cartilaginous fishes display _____ body temperature regulation, meaning they are cold-blooded.
Cartilaginous fishes display _____ body temperature regulation, meaning they are cold-blooded.
Match the following fish with their respective characteristics:
Match the following fish with their respective characteristics:
Which of the following characteristics is common to all bony fishes?
Which of the following characteristics is common to all bony fishes?
Which class of vertebrates is characterized by a lack of jaws?
Which class of vertebrates is characterized by a lack of jaws?
Both cartilaginous and bony fishes have a two-chambered heart.
Both cartilaginous and bony fishes have a two-chambered heart.
What is the primary method of fertilization for most bony fishes?
What is the primary method of fertilization for most bony fishes?
The class Chondrichthyes has a bony endoskeleton.
The class Chondrichthyes has a bony endoskeleton.
What is a key feature of the skin of Chondrichthyes?
What is a key feature of the skin of Chondrichthyes?
Cyclostomes exhibit a __________ type of circulation.
Cyclostomes exhibit a __________ type of circulation.
Match the following vertebrate classes with their primary characteristic:
Match the following vertebrate classes with their primary characteristic:
Which of the following animals is an example of a cyclostome?
Which of the following animals is an example of a cyclostome?
Cyclostomes can survive indefinitely in freshwater.
Cyclostomes can survive indefinitely in freshwater.
Name one example of a class within the superclass Tetrapoda.
Name one example of a class within the superclass Tetrapoda.
Which of the following statements is true regarding ctenophores?
Which of the following statements is true regarding ctenophores?
Flatworms are exclusively external parasites.
Flatworms are exclusively external parasites.
What type of body organization do aschelminthes possess?
What type of body organization do aschelminthes possess?
Flatworms exhibit __________ symmetry and are __________ in body structure.
Flatworms exhibit __________ symmetry and are __________ in body structure.
Which of the following is NOT a characteristic feature of birds?
Which of the following is NOT a characteristic feature of birds?
Match each phylum with its key characteristic:
Match each phylum with its key characteristic:
How do flatworms primarily absorb nutrients?
How do flatworms primarily absorb nutrients?
All birds are capable of flight.
All birds are capable of flight.
In aschelminthes, males and females are separate.
In aschelminthes, males and females are separate.
What are the two additional chambers found in the digestive tract of birds?
What are the two additional chambers found in the digestive tract of birds?
Mammals possess _______ glands that produce milk for their young.
Mammals possess _______ glands that produce milk for their young.
Name one example of a flatworm.
Name one example of a flatworm.
Match the following animals with their classifications:
Match the following animals with their classifications:
Which of the following adaptations can be found in mammals?
Which of the following adaptations can be found in mammals?
Birds have a two-chambered heart.
Birds have a two-chambered heart.
What physiological characteristic enables birds to maintain a constant body temperature?
What physiological characteristic enables birds to maintain a constant body temperature?
Which of the following characteristics is NOT true for chordates?
Which of the following characteristics is NOT true for chordates?
Urochordates retain the notochord throughout their life.
Urochordates retain the notochord throughout their life.
Name one example of a Cephalochordate.
Name one example of a Cephalochordate.
All vertebrates exhibit a __________ during their embryonic stage.
All vertebrates exhibit a __________ during their embryonic stage.
Match the following subphyla with their characteristics:
Match the following subphyla with their characteristics:
Which statement most accurately describes the central nervous system of chordates?
Which statement most accurately describes the central nervous system of chordates?
All chordates possess a post-anal tail.
All chordates possess a post-anal tail.
What part of the circulatory system do chordates possess?
What part of the circulatory system do chordates possess?
Which of the following is a characteristic of cartilaginous fishes?
Which of the following is a characteristic of cartilaginous fishes?
Osteichthyes are characterized by having a bony endoskeleton.
Osteichthyes are characterized by having a bony endoskeleton.
What type of reproduction is most commonly seen in bony fishes?
What type of reproduction is most commonly seen in bony fishes?
Cartilaginous fishes include species such as ______ and ______.
Cartilaginous fishes include species such as ______ and ______.
Match the following examples of fish with their classifications:
Match the following examples of fish with their classifications:
Which of these features distinguishes cartilaginous fishes from bony fishes?
Which of these features distinguishes cartilaginous fishes from bony fishes?
All members of Osteichthyes are viviparous.
All members of Osteichthyes are viviparous.
Bony fishes have ______ which helps in regulating buoyancy.
Bony fishes have ______ which helps in regulating buoyancy.
Which of the following groups of animals are characterized by the presence of a notochord at some stage of their life cycle?
Which of the following groups of animals are characterized by the presence of a notochord at some stage of their life cycle?
All arthropods have a hard external skeleton made of chitin.
All arthropods have a hard external skeleton made of chitin.
What distinguishes Chondrichthyes from Osteichthyes?
What distinguishes Chondrichthyes from Osteichthyes?
Echinoderms possess a unique feature called the __________ system.
Echinoderms possess a unique feature called the __________ system.
Match the following groups of vertebrates with their characteristics:
Match the following groups of vertebrates with their characteristics:
Which of the following groups of animals are considered poikilothermous?
Which of the following groups of animals are considered poikilothermous?
All mammals exhibit viviparity.
All mammals exhibit viviparity.
What is a common feature of Agnatha?
What is a common feature of Agnatha?
What type of symmetry is found in Echinodermata depending on their stage?
What type of symmetry is found in Echinodermata depending on their stage?
All members of the phylum Porifera are known for their symmetry.
All members of the phylum Porifera are known for their symmetry.
What structure in sponges allows for the flow of water for respiration and waste removal?
What structure in sponges allows for the flow of water for respiration and waste removal?
Animals that possess a notochord are called ______.
Animals that possess a notochord are called ______.
Match the following classifications with their brief descriptions:
Match the following classifications with their brief descriptions:
What type of reproductive strategy do sponges utilize?
What type of reproductive strategy do sponges utilize?
Sponges have separate sexes for reproduction.
Sponges have separate sexes for reproduction.
What are the supportive structures found in sponges called?
What are the supportive structures found in sponges called?
Which of the following features is present in Chordates but absent in Non-Chordates?
Which of the following features is present in Chordates but absent in Non-Chordates?
All vertebrates are chordates, but not all chordates are vertebrates.
All vertebrates are chordates, but not all chordates are vertebrates.
Provide an example of a member from the subphylum Urochordata.
Provide an example of a member from the subphylum Urochordata.
In Cephalochordata, the notochord extends from head to _____ region.
In Cephalochordata, the notochord extends from head to _____ region.
Match the following subphyla with their notable characteristics:
Match the following subphyla with their notable characteristics:
Which characteristic is NOT associated with Chordates?
Which characteristic is NOT associated with Chordates?
The notochord in Urochordata is present throughout the organism's life.
The notochord in Urochordata is present throughout the organism's life.
What type of circulatory system do chordates generally possess?
What type of circulatory system do chordates generally possess?
What type of heart do cartilaginous fishes possess?
What type of heart do cartilaginous fishes possess?
All cartilaginous fishes are viviparous.
All cartilaginous fishes are viviparous.
Name an example of a freshwater bony fish.
Name an example of a freshwater bony fish.
Cartilaginous fishes lack an __________, so they must swim constantly to avoid sinking.
Cartilaginous fishes lack an __________, so they must swim constantly to avoid sinking.
Match the following fish with their classification:
Match the following fish with their classification:
Which characteristic is true for Osteichthyes?
Which characteristic is true for Osteichthyes?
The pelvic fins of male cartilaginous fishes are modified to bear claspers.
The pelvic fins of male cartilaginous fishes are modified to bear claspers.
What is the term used for animals that cannot regulate their body temperature?
What is the term used for animals that cannot regulate their body temperature?
Which of the following is NOT a characteristic feature of Aves?
Which of the following is NOT a characteristic feature of Aves?
All members of the class Aves can fly.
All members of the class Aves can fly.
Name one adaptation that mammals have developed to thrive in various habitats.
Name one adaptation that mammals have developed to thrive in various habitats.
The additional chambers in the digestive tract of birds are known as the ______ and gizzard.
The additional chambers in the digestive tract of birds are known as the ______ and gizzard.
Which of the following statements about mammals is true?
Which of the following statements about mammals is true?
Match the following birds with their characteristics:
Match the following birds with their characteristics:
The heart of birds is completely three-chambered.
The heart of birds is completely three-chambered.
What is the primary mode of respiration in birds?
What is the primary mode of respiration in birds?
Which of the following animals is oviparous?
Which of the following animals is oviparous?
All mammals have a three-chambered heart.
All mammals have a three-chambered heart.
What is a distinctive feature of coelenterates?
What is a distinctive feature of coelenterates?
Mammals are characterized as being ______thermous.
Mammals are characterized as being ______thermous.
Match the following animals with their type of reproduction:
Match the following animals with their type of reproduction:
Which of the following statements about respiration in mammals is true?
Which of the following statements about respiration in mammals is true?
Sexes in mammals are separate and fertilization is internal.
Sexes in mammals are separate and fertilization is internal.
Name one example of a viviparous animal.
Name one example of a viviparous animal.
What type of symmetry do echinoderms exhibit?
What type of symmetry do echinoderms exhibit?
All animals with a notochord are classified under the group called chordates.
All animals with a notochord are classified under the group called chordates.
Name the primary supportive structures found in sponges.
Name the primary supportive structures found in sponges.
The central cavity in sponges through which water flows is called the ______.
The central cavity in sponges through which water flows is called the ______.
Match the following phyla with their common characteristics:
Match the following phyla with their common characteristics:
What is the term for the water transport pathways in sponges?
What is the term for the water transport pathways in sponges?
Sponges are characterized by separate sexes.
Sponges are characterized by separate sexes.
What is the process by which sponges reproduce sexually?
What is the process by which sponges reproduce sexually?
Which of the following characteristics applies to cartilaginous fishes?
Which of the following characteristics applies to cartilaginous fishes?
All bony fishes are viviparous.
All bony fishes are viviparous.
What is the function of the air bladder in bony fishes?
What is the function of the air bladder in bony fishes?
Cartilaginous fishes, like sharks and rays, are categorized as ______ animals.
Cartilaginous fishes, like sharks and rays, are categorized as ______ animals.
Match the following fishes with their classification:
Match the following fishes with their classification:
Which of the following is a notable feature of male cartilaginous fishes?
Which of the following is a notable feature of male cartilaginous fishes?
Both cartilaginous and bony fishes have a four-chambered heart.
Both cartilaginous and bony fishes have a four-chambered heart.
Name an example of a viviparous fish.
Name an example of a viviparous fish.
What characteristic distinguishes chordates from non-chordates?
What characteristic distinguishes chordates from non-chordates?
All chordates possess a vertebral column in their adult form.
All chordates possess a vertebral column in their adult form.
Name a trait that all vertebrates share during their embryonic period.
Name a trait that all vertebrates share during their embryonic period.
Members of the subphylum _________ are known as protochordates and are exclusively marine.
Members of the subphylum _________ are known as protochordates and are exclusively marine.
What is a common feature of Cephalochordata?
What is a common feature of Cephalochordata?
Match the following subphyla with their examples:
Match the following subphyla with their examples:
All chordates have three distinct subphyla.
All chordates have three distinct subphyla.
What is absent in non-chordates that is present in chordates?
What is absent in non-chordates that is present in chordates?
Which characteristic is unique to mammals?
Which characteristic is unique to mammals?
Birds have hollow bones to aid in flight.
Birds have hollow bones to aid in flight.
What are the two additional chambers found in a bird's digestive system?
What are the two additional chambers found in a bird's digestive system?
The forelimbs of birds are modified into ______.
The forelimbs of birds are modified into ______.
Match the following animals with their respective classes:
Match the following animals with their respective classes:
Which of the following is a characteristic of the class Aves?
Which of the following is a characteristic of the class Aves?
The heart of birds is only three-chambered.
The heart of birds is only three-chambered.
Name one flightless bird.
Name one flightless bird.
Which of the following animal phyla exhibits radial symmetry?
Which of the following animal phyla exhibits radial symmetry?
All arthropods possess a complete digestive system.
All arthropods possess a complete digestive system.
What type of skeleton do mollusks possess?
What type of skeleton do mollusks possess?
Cnidarians have stinging cells called ______.
Cnidarians have stinging cells called ______.
Match the following animal phyla with their characteristics:
Match the following animal phyla with their characteristics:
Which characteristic distinguishes Hemichordata from other phyla?
Which characteristic distinguishes Hemichordata from other phyla?
Annelids exhibit radial symmetry.
Annelids exhibit radial symmetry.
The __________ level of organization is characterized by the presence of tissues grouped together to form organs.
The __________ level of organization is characterized by the presence of tissues grouped together to form organs.
Which group is characterized by a water vascular system?
Which group is characterized by a water vascular system?
All vertebrates are classified as chordates.
All vertebrates are classified as chordates.
Name two modifications observed in birds that assist in flight.
Name two modifications observed in birds that assist in flight.
The first observation of segmentation in the body is in __________.
The first observation of segmentation in the body is in __________.
Match the following structures with their respective phyla:
Match the following structures with their respective phyla:
Which of the following birds is flightless?
Which of the following birds is flightless?
All birds have the ability to fly.
All birds have the ability to fly.
What is the most unique characteristic of mammals?
What is the most unique characteristic of mammals?
The respiratory system of birds includes _____ connected to the lungs.
The respiratory system of birds includes _____ connected to the lungs.
Match the following animal classifications with their examples:
Match the following animal classifications with their examples:
Which of the following features is NOT typically found in birds?
Which of the following features is NOT typically found in birds?
What type of fertilization do birds undergo?
What type of fertilization do birds undergo?
Birds have a three-chambered heart.
Birds have a three-chambered heart.
Which of the following features distinguishes chordates from non-chordates?
Which of the following features distinguishes chordates from non-chordates?
All chordates retain their notochord throughout their lives.
All chordates retain their notochord throughout their lives.
Name the three subphyla of Phylum Chordata.
Name the three subphyla of Phylum Chordata.
In Urochordata, the notochord is only present in the ______ stage.
In Urochordata, the notochord is only present in the ______ stage.
Which of the following correctly describes the central nervous system in non-chordates?
Which of the following correctly describes the central nervous system in non-chordates?
Match the following examples with their subphylum:
Match the following examples with their subphylum:
All vertebrates are also classified as chordates.
All vertebrates are also classified as chordates.
What is the main characteristic of the heart in chordates?
What is the main characteristic of the heart in chordates?
Which of the following options correctly describes the reproductive methods of sponges?
Which of the following options correctly describes the reproductive methods of sponges?
Cnidarians exhibit only one body form, either polyp or medusa.
Cnidarians exhibit only one body form, either polyp or medusa.
What is the name of the stinging cells found in cnidarians?
What is the name of the stinging cells found in cnidarians?
Cnidarians have a ____________ cavity with a single opening.
Cnidarians have a ____________ cavity with a single opening.
Match the following examples with their respective categories:
Match the following examples with their respective categories:
Which of the following correctly describes the body structure of ctenophores?
Which of the following correctly describes the body structure of ctenophores?
Corals, a type of cnidarian, have a skeleton made of calcium carbonate.
Corals, a type of cnidarian, have a skeleton made of calcium carbonate.
What type of generation do cnidarians exhibit that involves both asexual polyp and sexual medusa?
What type of generation do cnidarians exhibit that involves both asexual polyp and sexual medusa?
What are the main characteristics of arthropods?
What are the main characteristics of arthropods?
Echinoderms have a water vascular system that is their most distinctive feature.
Echinoderms have a water vascular system that is their most distinctive feature.
Name the two superclasses of Gnathostomata.
Name the two superclasses of Gnathostomata.
The most primitive chordates are represented by the class ______.
The most primitive chordates are represented by the class ______.
Match the following animal classes with their defining features:
Match the following animal classes with their defining features:
Which of the following statements about mammals is correct?
Which of the following statements about mammals is correct?
All vertebrates possess jaws.
All vertebrates possess jaws.
What key feature do most chordates share?
What key feature do most chordates share?
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.
- Levels of Organization:
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 Chondrichthyes (Cartilaginous fishes)
- 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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Description
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.
