On rare occasions they are killed by polar bears or killer whales. They help to keep the balance of Marine life. Walruses' act of finding food helps control the number of some species， prevent them from overmuch for breeding. When walruses hunt seals, walruses hug each other with their forelimbs, drown it under water and eat. A walrus' tentacles and sensitive snout help it find food. But the Global warming has caused the glacier to melt, which has had a serious impact on the survival of walruses.