Erignathus attempts to avoid the polar bear by resting very near the water and diving immediately when disturbed. It evidently has good vision and hearing and a fair sense of smell. It is able to make breathing holes through thin ice by ramming with its head. Dives to depths of 200 meters have been reported, but most feeding is done in shallower waters. The diet varies by area but consists almost entirely of bottom-dwelling animals.
Important items are crabs, shrimps, gastropods, clams, whelks, arctic cod, and flounder.
The whiskers may be used to help sort out smaller food organisms. Erignathus tends to be solitary, though loose aggregations sometimes form at favorable hauling-out sites. This sound is known to be made only by mature males during the spring and may be a proclamation of territory or breeding condition. Mating occurs mainly in the first three weeks of May in Alaska and the Canadian Arctic, and from the end of March to late May in the Barents Sea. Implantation of the blastocyst is delayed about 2 months, until July or early August.