What is "trichecus obesus"

Walrus \Wal"rus\, n. [D. walrus; of Scand. origin; cf. Dan valros, Sw. vallross, Norw. hvalros; literally, whale horse; akin to Icel. hrosshvalr, AS. horshw[ae]l. See Whale, and Horse.] (Zo["o]l.) A very large marine mammal ( Trichecus rosmarus) of the Seal family, native of the Arctic Ocean. The male has long and powerful tusks descending from the upper jaw. It uses these in procuring food and in fighting. It is hunted for its oil, ivory, and skin. It feeds largely on mollusks. Called also morse.

Note: The walrus of the North Pacific and Behring Strait ( Trichecus obesus) is regarded by some as a distinct species, by others as a variety of the common walrus.