Manatees are marine mammals.
Manatees are marine mammals, like dolphins and whales. But they don't share a dolphin's sleek shape. Instead, they are slow, bloated animals that look like a pig or hippopotamus set to sea. And like livestock, they graze on vegetation, such as sea grasses. A fifth species, the Stellar's sea cow, used to live off the coast of Alaska, but hunters drove it to extinction in 1768, less than 20 years after it was first described by shipwrecked Russian explorers.