Atlantic walruses (Odobenus rosmarus rosmarus). This large, gregarious relative of the seal has tusks that can reach a metre in length. Both the male (bulls) and female (cows) have tusks. The bulls use them in displays and fights when competing for dominance and access to cows. Both males and females use tusks to haul themselves onto ice or to create breathing holes. The walrus dives to the ocean floor to feed on mussels, crabs, snails and starfish. Photographed in July on a beach in Norway's Svalbard archipelago in the Arctic.