Manatees may seem slow and sleepy, but they have some surprising tricks under the surface. For starters, they are one of the few mammals that constantly replace their teeth. As old molars wear down from chewing gritty seagrass, new ones slowly roll forward like a conveyor belt—handy for an animal that eats for up to eight hours a day.

These gentle giants are also close relatives of elephants, which explains their wrinkled skin and flexible upper lips used to grab plants. Despite their size, they have very little body fat, making them sensitive to cold water and dependent on warm springs during winter. Manatees are a reminder that even animals that may look like floating potatoes with flippers can be fascinating—and still need our protection.