The term Plant-Eating Aquatic Mammal is referring to the Manatee, a large aquatic mammal found in warm coastal waters. Manatees are herbivores, meaning they feed on plants and algae. They are slow-moving animals and can grow up to 13 feet long and weigh up to 1, 300 pounds. Manatees are an endangered species due to human activities such as boat strikes, fishing gear entanglement, and habitat destruction.