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Classification of vertebrate zoology (class Amphibia)

Class Amphibia (Amphibians)

Class Amphibia includes the animals, which are adopted to double mode of life, i.e. on land or in water. These were the first vertebrates that could lead a terrestrial existence. About 1500 species of amphibians are living today and their fossils are also numerous. Amphibians are said to originate from crossopterygian ancestors (extinct fishes).

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  •   Amphibians animals lives on land as well as in water.
  •  Their body differentiated into head, trunk, and tail. The tail is absent in Anura (order).
  •  Body with two pairs of pentadactyle limbs. Forelimbs with four digits and hind limbs with five digits.
  • Digits without claws.
  • Head with a pairs of nostrils leading to buccal cavity.
  • Skin naked without scale, scutes or bony plates but with glands. It help in respiration.
  • Skull with two occipital condyles, cranium, cartilages.
  • Amphibians having maxillary and vomerine teeth.
  • Ribs in amphibians are usually absent but if it is present these are not attach to sternum.
  • Amphibians can respire through gills, lungs or skin.
  • Amphibians having heart with three chambered, two auricle and one ventricle. although sinus venous and reduced conus arteriosus are present.
  • Amphibians are having arterial system with two systemic arches as well having venous system with both hepatic and renal portal system.
  • Their blood corpuscles are nucleated.
  • Amphibians are having ten pairs of cranial nerves.
  • Their brain well developed with cerebral hemispheres but poorly developed with cerebellum.
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Resemblance of Amphibians with fishes;

  •   Amphibia resemble the fishes in the following characters;                                            
  •   Presence of ten pairs of cranial nerves.
  •   Presence of pronephros (primitive Kidney) type of kidney in larva.
  •   The resemblance in early development.
  •   Absence of amnion and allantois.
  •   Presence of lateral line sense organs.

Amphibians differ from fishes but resemble with Reptiles in the following respects.

  • Absence of fin rays.
  • Presence of Pentadactyle limbs.
  • Presence of Auditory capsules.
  • Absence of cardinal veins in the adult.
  • Presence of cloaca.
Classification of vertebrate zoology ( class Amphibia)