Sea cow is a term sometimes applied to the dugong and manatee, which belong to an order (group) of sea mammals called Sirenia. But the term more correctly applies to an extinct animal called Steller’s sea cow. The Steller’s sea cow was discovered in 1741 near the Commander Islands in the Bering Sea. The total population then probably numbered between 1,000 to 2,000. Sailors killed the animals for food, and by 1768 they were extinct. The Steller’s sea cow lived in shallow water near shore. It fed on seaweed. It was the largest sirenian (member of the Sirenia order of sea mammals) and the only one adapted to cold water. It grew to 25 feet (7.6 meters) long and weighed up to 11 tons (10 metric tons). See also Dugong ; Manatee ; Sirenia . 
