(Hydrodamalis stelleri, or H. gigas), a marine mammal of the order Sirenia. Steller’s sea cow was discovered and described in 1741 by G. Steller, who was a naturalist on the expeditions of V. I. Bering. It was up to 8 m long and weighed up to 3.5 tons. The massive spindle-shaped trunk ended in a horizontal fin. The forelimbs were in the form of flippers; posterior extremities were absent. The black skin was naked, thick, and very coarse. Steller’s sea cows were toothless, but the palate and the edge of the lower jaw were covered with ribbed horny plates. The mammals lived in herds near the Komandorskie Islands in shallow waters and fed on marine algae (sea kale). Hunted for their flesh and fat, Steller’s sea cows were exterminated somewhere around 1765.