Now they know that manatees are more closely related to elephants than any other living animal. Scientists believe that manatees evolved from land mammals that returned to an aquatic life. Manatees are large marine mammals weighing up to 2000 pounds and reaching more than 12 feet in length. Like whales, their large bodies can only be supported in their watery environment. On land, their body weight would crush their internal organs.
Manatees are the only marine mammals that are herbivores.
Just to keep their big bodies warm, they have to eat up to one tenth of their body weight every day. Warm Water Mammals Keeping warm is a real problem for these animals. Their cylindrical bodies help conserve heat, but they don't have the blubber that other marine mammals do. Their metabolism is also very low, so they don't generate a lot of body heat. In cold water, they can develop pneumonia, get too sluggish to eat, and can die.