Walruses (Odobenus rosmarus) are instantly recognizable by their ivory tusks—useful tools for life on the ice. Walruses hook their tusks into ice floes to help haul their bodies from the water, but more often they display these huge teeth to intimidate others and use them to joust for prime real estate. When winter ice blankets the sea, tusks make good ice picks to help maintain breathing holes or rescue a stranded calf.

Walrus herds can contain thousands of individuals that pile onto ice platforms and seasonally onto beaches. These marine mammals spend most of their lives at sea, migrating with the ice, which extends south in winter and retreats north in summer.

Great Gatherings
Walruses travel together in large herds that are closely linked to the sea ice.

Walruses typically crowd together more than their fellow pinnipeds, or fin-footed marine mammals. Adult males and females live in separate herds during the summer and group together during the winter, when mating occurs. But even same-sex packs huddle closely together, and mothers keep their calves close by.

Females give birth and raise their calves on shifting pack ice. Most males, however, head to haul-out sites on land during the nonbreeding season. No matter what their location—on the ice or on the beach—walruses pile on top of each other even if there's room to spread out.

A biologist helps an indigenous hunter haul a freshly killed walrus. Field experts in their own right, native people provide accurate accounts of walrus migratory patterns, herd sizes and ice conditions. © Steve McCutcheon / Visuals Unlimited

CONSERVATION: Harvesting the Herd
Indigenous peoples of the Arctic region have long relied on walruses for meat, skins, ivory and bones. Native hunters teach their children about walruses and their habitat, encouraging awareness of the herds. And many communities today share this knowledge with wildlife biologists to help monitor these marine mammals—which were overhunted for commercial use as recently as the 1950s.

When whales weren't unavailable, commercial whalers killed walruses for blubber. Canada banned commercial hunting in 1867, decades before the United States, Greenland and Russia enacted effective laws. Such restrictions have helped the herds rebound, allowing indigenous hunters to harvest walruses as long as they use their catch responsibly and sell the ivory only as art and craft goods.

A walrus uses its sensitive whiskers, called "vibrissae," to detect invertebrates buried in the sand. Grabbing the shells with its lips, the walrus sucks out the soft-bodied animals, consuming 3,000 to 6,000 mollusks per feeding. © Bob Cranston / www.norbertwu.com

Moving head first along the sea floor, walruses blow jets of water to uncover mollusks buried in the sediment along continental shelf. Excavation is a good technique for finding burrowing prey, but the process creates huge pits and gullies and clouds the water.

Many animals, however, benefit from the altered ecosystem—including the walruses themselves. Blasting exposes new species for predators that colonize the pitted areas. Meanwhile, scavengers also feast on scraps in discarded mollusk shells. The sediment released into the water contains many nutrients consumed by tiny floating plankton. These plankton in turn feed mollusks, which the walruses eat. In a sense, the walruses are fertilizing their own gardens.