Question

Amphibians are wonderful creatures on the earth. How do you appreciate their adaptation?

Answer 1

Hint: In the five kingdom classification system, kingdom Animalia includes several phylums. The Phylum Chordata of animal kingdom is divided into two groups namely Protochordates and Chordata on the basis of cranium, vertebral column and paired appendages. Further Urochordata includes the subphylum Vertebrata that ultimately consists of superclasses such as pisces, amphibia, reptilia, aves and mammalia. Among these animals, amphibians are considered to be the connecting link between aquatic and terrestrial animals.

Complete answer: Class amphibia includes animals which can live on both the places at ease, that is underwater and on land. These are the first chordate animals which came out of water but these are not able to live on land permanently because they are dependent on water for their reproduction. Their eggs do not have protective covering to check the evaporation. These animals undergo hibernation or aestivation to protect themselves from extreme cold and heat and to overcome unfavorable conditions.
Their skin is moist, smooth and scaleless. Numerous mucous glands are found in the skin which helps in moistening of skin. So these animals respire mainly through their moist skin (cutaneous respiration). Some amphibians also respire through gills, lungs and buccopharyngeal cavities.
These are cold blooded (poikilothermic) animals having a three chambered heart, along with renal and hepatic portal systems. Most of these perform external fertilization which takes place in water and hence are dependent on water for their reproduction. They are oviparous animals and lay their eggs in water.
Thus amphibians have so many adaptations for their survival on earth.

Note: Amphibians are classified into three orders namely- Apoda, Caudata and Anura on the basis of pairs of limbs and presence of tail on their body.
Apoda are the primitive limbless amphibians and their body is worm-like burrowing in nature. Caudata have two pairs of equal size limbs and they are called tailed amphibians. Anura are the modern amphibians and they lack tail (tailless amphibians). The development of some amphibians undergo larval stages such as Axolotl larval stage and tadpole larval stage.