Manatees are mammals. A manatee gives birth to one pup. They produce a pup every two to three years. The pup stays with its mother for two years. When the youngsters are born they are brown. Baby manatees turn gray in a month. The baby manatees stop nursing in three months. The babies are usually sixty pounds at birth. When they are a full grown they are thirteen feet long, and get up to 3,500 pounds. Hopefully they will live forty to seventy years.