Is a manatee related to a walrus?

No, a manatee is not closely related to a walrus. Manatees are part of the order Sirenia, which includes sea cows, while walruses belong to the order Pinnipedia, which includes seals and sea lions. Both are marine mammals, but they have different evolutionary histories and adaptations. Manatees are herbivorous, while walruses are carnivorous.