Amphifian's world

The name amphibian comes from some Greek words which mean 'living in two places'. This is an apt descrip-tíon of the animals called the amphi­bians, as they divide their lives between water and land. Today they are all small animals, the largest being the giant salamander of the Far East, which grows to a length of about one and a half metres (five feet), but in the prehistoric past they included some which grew to three and a half metres (twelve feet) long.

Today there are about 2,000 different species of amphibians, mostly living in the warmer and damper regions of the world. They can be classified into three groups: first the caecilians or blindworms, a small tropical group of burrowing animals; second the newts and salamanders; and third, the frogs and toads.


The typical amphibian starts life in the water. The pattern of mating behaviour varíes greatly between the different species, but the eggs which are produced are usually laid in large numbers. In frogs and toads they are fertilised externally, after they have left the female's body. In newts, although there is internal fertilisation, often there is no direct contact between the pair. Many of the tropical amphibians have developed methods of protecting the eggs. They do this by making a nest in which the eggs hatch, or by providing parental protection, or by laying shelled eggs, or by producing living young. But in general the spawn has only a gelatinous outer covering. This is protective to some extent, but it soon becomes dried up if there is no water. And it is no help against the many predators, including fish and birds, which can make short work of amphibians' eggs.

Helpless as they appear to be in the face of enemies, the amphibians have a number of lines of defence. The most important are the poison glands in the skin, the largest of which lie just behind the head and can be seen quite easily in toads and some sala­manders. When stimulated they produce a whitish fluid, which is extremely irritating to the eyes, mouth and nose of any animal investigating the amphibian too closely. In some species in which these glands are well developed a pattern of warning colouration also occurs. The fire salamander of mainland Europe, for example, has dazzling yellow and black colours, a clear warning to predators not to attack. Any animal which is foolish enough to do so will have a very unpleasant experience, and will remember the general colour pattern and avoid similar looking animals in future.

All amphibians feed on insects, snails, worms, grubs, or even young of their own kind. They are capable of surviving long periods without food, but may be extremely greedy when it becomes available.