Most sharks are nocturnal feeders; however, feeding during the day is also common. Most sharks hunt alone, but have been found in pairs or small groups, or in some cases large groups. Sharks consume relatively small amounts of food (3-5% of their body weight) at one- to two-day intervals. They feed intensively for a short period and then feed very little for a longer period and are able to stop feeding for several weeks at a time. During these times, sharks rely on oil reserves in their large livers.
Sharks are opportunistic and often indiscriminate feeders. Most species are carnivores and feed on a wide variety of prey in a wide variety of sizes. Whale sharks (top left) are filter feeders that strain planktonic organisms from the water, while shortfin mako sharks (bottom left) feed on marine mammals. Some sharks feed primarily on live prey, others on diseased, wounded or dead animals. Diet is related to the age and size of a shark. As sharks grow, their diet will vary considerably. There is also considerable variation in diet from one location or season to the next. This variation is attributed to the availability of prey.