Steller's Sea Cow (Hydrodamalis gigas) is an extinct mammal from the order Sirenia in the animal kingdom, which also includes the manatee and dugong. It got its name from the man who discovered it, Georg Steller. The Steller's Sea Cow was hunted to extinction in the 18th century, only 30 years after its discovery. It was slaughtered for its meat and leather. It could weigh up to 11,000 kilograms. The Steller's sea cow did not have any teeth and did not need to, as it ate algae and sea grass. Herds included juveniles, as well as adult males and females. Juveniles were kept in the center of the herd to protect them. Steller (its discoverer) noted that the animal was monogamous and the pair bond was quite strong. He also noted that the sea cow could only be submerged for about four to five minutes. This makes the sea cow an easy target for hunters. From wikipedia on the Steller's sea cow: "There are still sporadic reports of sea cow-like animals from the Bering area, the Arctic, and Greenland, so it has been suggested that small populations of the animal may have survived to the present day. This remains so far unproven."
The Steller's sea cow is listed as Extinct (EX), there is no reasonable doubt that the last individual has died, on the IUCN Red List of Threatened Species
