Amphibians are a small group of cold-blooded, vertebrate animals. They include two main groups: the salamanders and newts, and the frogs and toads. The word “amphibian” means “double life”. Most amphibians spend the first part of their lives underwater, taking in oxygen from the water through gills, like fish. Their adult lives, however, are spent on land, breathing air through lungs. They return to the water to lay their eggs.
Most amphibians have four limbs. Only the salamanders and newts have tails. All amphibians have moist skin, through which they can “breathe in” oxygen in the water. They can also take in or lose water from their bodies through their skin. Because they need to keep their skin moist, most amphibians spend much of their time in cool, damp conditions. Many live in or near water, even as adults.
Amphibians undergo metamorphosis, a change in the body from young to adult. The most obvious change in salamanders and newts is that they lose their feathery gills and develop lungs. Frogs and toads change from plant-eating tadpoles with gills, a tail and no legs, to carnivorous, tail-less adults with lungs and long legs.
SALAMANDERS AND NEWTS
Salamanders and newts are long-bodied amphibians with long tails. They are often nocturnal, and are all carnivorous. They feed on insects, worms, slugs and snails, and the young also prey on frog tadpoles. Some salamanders live in water all the time, and several even keep their gills into adulthood. Others live on land but return to the water to lay their eggs. Newts will travel several kilometres to return to the breeding ponds where they grew up.
FROGS AND TOADS
Frogs and toads have short, tail-less bodies and long hind legs. Frogs are usually smooth-skinned. They spend most of their time in water. Their very long legs and streamlined bodies mean that they can make huge leaps and swim quickly. Toads have shorter legs, fatter bodies and lumpier skin. They live mostly on land, in dark, damp places to keep their skins moist and cool. Toads crawl or hop rather than leap.
Both frogs and toads usually lay their jelly-like eggs (spawn) in water, often returning to the same pond or lake year after year to breed. Some tree frogs lay their eggs inside a foam “nest” on an overhanging branch, so that when the tadpoles hatch, they will fall into the water. Many frogs and toads leave their eggs to hatch on their own. Others carry them on their backs to keep them safe. Mouth-brooding frogs hold their tadpoles in a throat sac, until they jump out as tiny frogs.
Frog and toad tadpoles mostly feed on water plants or filter algae from the water. As adults, however, they are carnivorous, feeding on insects, snails or worms. The larger frogs and toads will also eat fish, other frogs, and even small mammals.
In hot climates, toads and frogs burrow underground to avoid the heat of the day. Frogs that live in colder climates often spend winter in hibernation at the bottom of ponds, breathing through their skin.
Picture Credit : Google