Manatees descend from land animals that returned to the sea about 60 million years ago. Their closest relatives are the elephants and hyraxes, with which they share a common ancestor. The link to elephants may be seen in the gray, wrinkled skin covered in sparse, wiry hairs. While their limbs have evolved into flippers, including the rear limbs fusing into a paddle-like tail, the bones inside those flippers have the same structure as the elephants and hyraxes.
Today, only three species of manatees remain. The single other member of the Order Sirenia is the dugong, which lives in Asia. All browse on vegetation underwater. They sink to the bottom and use their front flippers to maneuver forward as they graze. They can reach sizes up to 13 feet long and 1,300 pounds.