The ecosystem is a composed of biotic and aboitic factors. There is an intricate association of all these components. Amphibians – frogs, toads, salamanders, newts and caecilians are animals that are indicators of the health of the ecosystem. Yet, amphibians are among the most ‘neglected’ groups of vertebrates and the reason partly lies in the definition of this term ‘amphibian’.
We all know that ‘the animals that live on both land and in water are amphibians’. This is a widely accepted definition of amphibians. If this is true, then crocodiles and turtles are also amphibians, but they are better known as reptiles.
In Greek amphibious means ‘life of both kinds’ (amphi meaning ‘of both kinds’ and bios meaning ‘life’) and the word amphibian is derived from this. Thus the correct definition of amphibians is ‘the animals that can live two kinds of lives – one on land and one in water’. Frogs breed in water; eggs are laid in water/ moist places, the larval life cannot survive in the absence of water. Despite their lungs, they also need the oxygen from their moist skin for breathing. The larval forms have gills for breathing in their early stages of development. This is in contrast to the amphibious reptiles that stay in water but breathe through lungs and breed on land.
Varad Giri is Curator, Bombay Natural History Society. He can be reached at [email protected].