Caecilians have no limbs. For this reason, the smaller species look like worms, while the larger species with lengths up to 1.5 m look similar to snakes. The tail is short and the cloaca is near the end of the body. Their skin is smooth and usually dark in colour. Some species have colorful skins, though. Inside the skin are calcite scales. Due to their underground life the eyes are small. Skin often covers them, to protect them. This has led to the idea that they are blind, which is not the case. Because of the skin cover, their "seeing" is limited to simple dark-light perception. They can tell the difference between dark and light. All Caecilians have two tentacles at their head. The tentacles are probably used for a second smelling capability in addition to the normal sense of smell based in the nose.