Evolved in the Devonian period and dominated in the Carboniferous period (age of amphibians).

VVI Examples of Amphibia for Entrance Exams of Nepal:
  • Ichthyophis
  • Ambystoma (Tiger salamander)
  • Rana tigrina (Frog)
  • Bufo (Toad)

· Amphibious mode of life, Poikilothermal (cold-blooded).
· Skin: Moist, glandular, slippery with no scales.
· Respiration through the skin, buccal cavity, and lungs.
· 3-chambered heart and symmetrical aortic arches.
· Double circulation. Ventricles pump mixed blood.
· Nucleated biconvex RBCs.
· Dicondylic skull.
· Teeth homodont.
· Presence of 10 pairs of cranial nerves
· Middle ear has single bone Columella Auris and a stapedial plate.
· Digits pentadactyle.
· Egg: Mesolecithal
· Kidneys: Pronephric in the larvaMesonephric in adults.
· Ureotelic mode of excretion (Salamanders are ammonotelic).
· Sexual dimorphism, oviparous, presence of tailed tadpole larva during development.
· Anamniota e.g. Ichthyophis, Ambystoma (Tiger salamander), Rana (Frog), Bufo (Toad)

Remember, Tree Frog is Hyla whereas Flying Frog is Rhacophorus.

Amphibians are divided into 3 orders.

a) Apoda: Limbless amphibians
· No limb.
· Also called caecilians or blindworms.
Example: Ichthyophis

b) Anura
· Commonly called frogs and toads.
· Tailless amphibians

c) Urodela
· Have tail and limbs.
· Presence of neotany and paedogenesis.
· Commonly called newts and salamanders.


S.N Frog Toad
1. The frog lives mostly in water or nearby water. Toad lives in moist damp places or in grasses, under a stone, or in dark shady places.
2. It is diurnal. It is nocturnal.
3. Its skin is moist and slippery with numerous mucous glands. It has respiratory function also. Its skin is rough or warty, dry, and has many poisonous glands than mucus gland
4. Its snout is pointed, has teeth in the upper jaw. The snout is blunt and has no teeth in both jaws
5. The presence of a vocal cord in a male frog produces a croaking sound. No vocal cord in both male and female so cannot produce sound.
6. Presence of webbed feet in hind limbs. Absence of webbed feet.
7. Absence of parotid gland. Presence of parotid gland.
8. The tongue is bifid. The tongue is entire.

Also, Read our Other Important Post for Entrance Exams:

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