The Steller's Sea Cow is a large dugong-like animal from the manatee family. It is thought that this animal became extinct in 1768. But soon after the extinction there was many sightings of this serenian. The Steller's Sea Cow lived/lives in the Bering Sea. Steller's Sea Cows are the largest serenians and could grow up to 30 feet (9 metres) long.