Amphibia General Characteristics, Classification and Examples | Free Biology Notes

Amphibia General Characteristics, Classification and Examples

After reading this article you will learn about Amphibia General Characteristics, Classification and Examples

Amphibia General Characteristics

  • They live in aquatic and terrestrial habitats
  • First chordate animals which came out of water but are not able to live on land permanently, as they depend on water for their reproduction
  • They are cold blooded animals
  • These animals undergo hibernation (winter sleep) or aestivation (summer sleep) to prevent themselves from extreme cold and heat and to overcome unfavourable condition
  • Body is divided into head and trunk. Tail may be present or absent
  • Two pairs of limbs present. Fore limbs have 4 digits and hind limbs have 5 digits
  • Skin is moist, glandular, smooth and scaleless
  • Numerous mucus glands are found on skin, which help in moistening the skin
  • Cutaneous respiration it means respiration occur through moist skin
  • Pigment cells are found called as chromatophore for colouration
  • Few amphibians have ability to change colour by expansion and contraction of pigment cells. This phenomenon is called metachrosis
  • Digestive system is well developed, complete alimentary canal along with digestive glands are present
  • Alimentary canal, urinary tract and reproductive tract open in a common chamber called cloaca
  • Eyes have eyelids
  • Respiration by gills, skins, lungs or Bucco pharyngeal cavity
  • Heart is 3 chambered 2 auricle and one ventricle and double circulation present
  • They are mostly ureotelic
  • Ear consist of internal and middle ear. Tympanum covers the middle ear.
  • Ten pairs of cranial nerves are present
  • Sexes are separate. Fertilisation is external. They are oviparous and development is indirect
  • Some members shows neoteny in which larva mature and start reproduction

Classification of Amphibia

The Amphibians are divided into three orders. The classification of amphibia is given below:

Order 1. Apoda or Gymnophiona

  • These are primitive limbless amphibians
  • Body worm like and burrowing in nature
  • Scales present but embedded in skin
  • Male has protrusible copulatory organ
  • Eye without eye lids
  • Parental care found

Examples of Apoda


  • Female coil around eggs and provide parental care
  • Tympannum absent
  • Also called blind and deaf worm

Order 2. Urodela or Caudata

  • Body is distinctly divided into head, trunk and tail
  • They are called urodella as tail is found life long
  • Two pairs of equal sized limbs present
  • Copulatory organ absent in male
  • Some members show neoteny
  • Scales are absent in them

Examples of Urodela

Necturus (Water dog or mud puppy)

  • It show permanent neoteny
  • Tympanum is absent
  • There are 3 pairs of external gills
  • Tail bears caudal fin and they are nocturnal

Ambystoma (Tiger salamander)

  • It exhibits the phenomenon of neoteny
  • When there is iodine deficiency in water, the axolotl don’t change into an adult

Order 3. Anura or Salientia

  • Tailless amphibian
  • Eyes with eyelids (lover lid movable and upper lid immovable)
  • Middle ear and tympanum present
  • Body divided into head and trunk. neck absent.
  • Fertilization is external and development through tadpole larva
  • Forelimb small and hind limb long

Examples of Anura

Hyla (Tree Frog)

  • It is adopted for life in trees
  • Large vocal sac present

Rhacophorus (Flying frog)

  • Webs developed between digits
  • parental care found

Bufo (Toad)

  • It inhibits on moist and dark shady places
  • It bears poisonous gland (Parotoid gland)

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