Ingo Arndt / Pacific walrus (Odobenus rosmarus divergens) bull in water, Round Island, Bering Sea, Bristol Bay, Alaska, USA

Ingo Arndt / Pacific Walrus (Odobenus rosmarus divergens) bull in water, Round Island, Bering Sea, Bristol Bay, Alaska

Ingo Arndt / Pacific Walrus (Odobenus rosmarus divergens) two bulls in water, Round Island, Bering Sea, Bristol Bay, Alaska, USA

Roland Seitre / Pacific Walrus (Odobenus rosmarus divergens) calf, native to northern Pacific

Sergey Gorshkov / Pacific Walrus (Odobenus rosmarus divergens) skull on tundra, Wrangel Island, Russia

Sergey Gorshkov / Polar Bear (Ursus maritimus) group feeding on Pacific Walrus (Odobenus rosmarus divergens) carcass on beach, Wrangel Island, Russia

Sergey Gorshkov / Pacific Walrus (Odobenus rosmarus divergens) large group hauled out on shore below stone cliffs, Wrangel Island, Russia

Sergey Gorshkov / Polar Bear (Ursus maritimus) group scavenging on Pacific Walrus (Odobenus rosmarus divergens) carcass, Wrangel Island, Russia

Steven Kazlowski / Walrus (Odobenus rosmarus) a cow fights off a bull's advances at the end of mating season, Bering Sea, off the coast of Alaska, USA

Yva Momatiuk & John Eastcott / Pacific Walrus (Odobenus rosmarus divergens) bull spraying water through nostrils to filter collected food, Round Island, Alaska

Yva Momatiuk & John Eastcott / Pacific Walrus (Odobenus rosmarus divergens) bull swimming in aggressive posture, Round Island, Bristol Bay, Alaska

Eric Baccega / Colony of Pacific walruses (Odobenus rosmarus) Round island, Alaska, North America