As with fish and reptiles, amphibians are cold-blooded. Unlike birds and mammals, they cannot make body heat to keep themselves at a constant warm temperature. Their bodies are usually at about the same temperature as the air or water around them. When they are warm, they can move actively. But in cold conditions they cannot. They become still and their body processes slow down. This is called torpor. In temperate regions, many amphibians are torpid or ‘asleep’ in winter.
| An amphibian begins its life as a small, dark dot like egg. This contains yolk for nourishment and is surrounded by several layers of jelly. It does not have a protective outer shell like a reptile egg, so it must be laid in water or moist surroundings to prevent drying out. Lots of jelly covered eggs clustered together are known as spawn. |  |
| The frog is probably the most well known of the amphibian family |
Amphibian eggs grow and become comma shaped, then hatch into larval amphibians or, tadpoles. These have feathery gills on the sides of the head for absorbing oxygen from the water. Most amphibians lose their gills when they become adults, and take the oxygen in through their lungs and moist skin. But some, such as the mudpuppy keep their gills through life.
More species of amphibians are being discovered every year, especially in thir main habitats, the tropical rainforests. There are three main kinds of amphibians. They are newts and salamanders, frogs and toads, and caecilians.
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A typical newt or salamander has a long lizard like body, a long tail, four usually small sprawling legs at its sides and smooth scale-less skin. Most are active in the evening or night, when they hunt for small creatures such as insects, spiders and worms. In fact all amphibians are predators. They cannot chew so they gulp down their victims whole, often still alive and struggling. |
| Newts are amphibians in the Salamandridae family |
