Amazonian manatee  (Trichechus inunguis)

The Amazonian manatee is a most bizarre-looking aquatic mammal, and was first described as a curious combination of a hippopotamus and a seal (6). Its body is large, dark grey to black and smooth-skinned, and its forelimbs are modified into flippers like a seal's (17). It has no hind limbs, and the rear of the body forms a flat, rounded horizontal paddle (7). The head is rounded, with nostrils on the upper surface of the snout (8). The Amazonian manatee is smaller and more slender than the other two manatee species (West Indian manatees Trichechus manatus and West African manatees T. senegalensis) (7). It can also be identified by the lack of nails on its flippers, a characteristic referred to in its scientific name, T. inunguis, which literally means ‘no nails' (9). A unique feature (amongst mammals) of the manatee is the constant replacement of molar teeth; new teeth enter at the back of the jaw and replace old and worn teeth at the front (10). Recent evidence suggests that manatees may possess a unique 6th sense that enables them to detect pressure changes through sensory hairs (11).