The
Steller's sea cow (
Hydrodamalis gigas) is an extinct
herbivorous marine mammal. It was the largest member of the order
Sirenia, which includes its closest living relative, the
dugong (
Dugong dugon), and the
manatees (
Trichechus spp.). It reached up to in length, making it among the largest mammals other than
whales to have existed in the
holocene epoch. Although the sea cow had formerly been abundant throughout the North Pacific, by 1741, when it was first described by
Georg Wilhelm Steller, chief naturalist on an
expedition led by explorer
Vitus Bering, its range had been limited to a single, isolated population surrounding the uninhabited
Commander Islands. Within 27 years of discovery by Europeans, the slow-moving and easily captured Steller's sea cow was hunted to
extinction.