They are members of very different classes of animals, but they are so similar, that they are often confused. Caecilians have no or almost no tail, breeze like frogs by moving the throat and have an always wet skin. Their habitat are the humid tropical- and subtropical regions of the earth. Seen from close, many caecilians have a small, shark like head. The external gills are lost quickly after hatching.
Caecilians own a very special organ on their head, it is an extendable small tentacle.
The tentacle serves them for smelling and encounter food. The position of the tentacle on the head is an important point to distinguish the different species of Gymnophionians. There are about 170 different species known on world. But snakes and lizards are much nearer related to one another, than amphisbaenians are to them. Therefore some scientist prefer to exclude them from the scaly reptiles and even open a new order of the Amphisbaeniata in reptile classi-fication.