Sea COW

Sea COW, any of an order (Sirenia) of tropical, herbivorous, aquatic mammals. Probably evolved from a marsh-dwelling ancestor related to the elephant, all serenians are completely seal-like with forelimbs modified into flippers and hindlimbs fused into the horizontal flukes of a whalelike tail. Genera include Trichechus (the manatee) and Dugong (the dugong).