Orcas hunt everything from fish to walruses, seals, sea lions, penguins, squid, sea turtles, sharks, and even other kinds of whales. Depending on the season and where they are, their diet varies—some orcas eat more fishes and squid than seals and penguins. But wherever they are in any of the world's oceans, average-sized orcas may eat about 500 pounds (227 kilograms) of food a day. Orcas have many hunting techniques, and bumping seals off ice is just one of them.
Often referred to as wolves of the sea, orcas live and hunt together in cooperative pods, or family groups, much like a pack of wolves. They work together as they hunt. Groups of orcas cooperate to herd fish into a compact area so that they're easier to eat. They will also slap their tails onto the water's surface, causing a wave to wash prey, such as penguins or sea lions, off ice floes and into the water. Sometimes a pod of whales will join forces to surround a larger animal, such as a blue whale. They chase, bite, and wear it down until it becomes a meal.
Orcas' teeth, numbering about 45 and each measuring about 3 inches (7.6 centimeters) long, are shaped for ripping and tearing prey. Orcas do not chew their food. They can swallow small seals and sea lions whole. The prey slides down the orcas' throats! Bigger prey is eaten in chunks. The color pattern of orcas may help them sneak up on and attack their prey. Their backs are black, their stomachs are white. Animals looking down on an orca from above, such as a seal on an ice floe, might not see it because the whale's dark back blends with the water below.
On the other hand, the whale's white underside blends with the light streaming down into the sea from the surface, making it hard to spot from below. With orcas camouflaged so well, those prey fish, penguins, or seals are likely to miss the danger heading their way, as the killer whale once again proves it is the oceans' superbly designed hunter.