Explain how animals in vertebrata are classified into further subgroups (no copy n paste criteria! )
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Vertebrata :
This subphylum is subdivided into seven classes. They are :-
- Cyclostomata
- Chondrichthyes
- Osteichthyes
- Amphibians
- Reptiles
- Aves
- Mammals
Cyclostomata :-
✯ Animals are jawless and possess a circular mouth.
✯ Head and brain are poorly developed.
✯ Respiration occurs through gills.
✯ Gonad is single and fertilization is external.
Chondrichthyes :-
✯ They have jawed vertebrates.
✯ They have paired fins, paired nares, scales, a heart with its chambers in series.
✯ Skeletons are made of cartilage rather than bone.
Osteichthyes :-
✯ Gills are covered by operculum.
✯ Swim bladder are usually present.
✯ Fertilization is external.
✯ 4-5 pair of gills are present.
Amphibians :-
✯ They are amphibious in nature; found in fresh water and moist places.
✯ Skin is smooth or rough, rich in glands which keep it moist.
Body is without scales.
✯ Heart three chambered and brain is not much developed.
Reptiles :-
✯ Two pair of pentadactyl limbs are present.
✯ Body is covered with epidermal horny scales.
✯ Skin is dry, impermeable and devoid of glands.
✯ Sexes are seperate.
Aves :-
✯ The body is covered with soft feathers called plumage.
✯ The body is divisible into head, neck, trunk and tail.
✯ Jaws are modified to form a strong beak.
✯ Fertilization is internal and no larval stage.
Mammals :-
✯ Skin is covered with exoskeleton of hair.
✯ Mammals have two pairs of pentadactyl limbs.
✯ Respiration occurs by gills.
✯ They give birth to living young ones and are called viviparous.
✯ The young ones are fed on milk from mammary glands.
Additional information :-
Characters of vertebrata :-
✯ They are advanced animals, having a cranium around the brain.
✯ Notochord is replaced by a vertebral column in the adults.
✯ There are two pairs of limbs or appendages.
✯ Heart is situated ventrally.
✯ Respiratory organs may be gills, skin, buccopharyngeal cavity or lungs.
✯ Head is well differentiated
✯ Excretion occurs through kidneys.
✯ Sexes are seperate.
Answer:
Vertebrates are further classified according to several criteria like exoskeleton, respiratory organs, method of giving birth, number of chambers in heart, mode of living etc. They are further classified into classes Pisces, Amphibia, Reptilia, Aves and Mammals.