Sharks are highly adapted predators with remarkably diverse diets, varying considerably across nearly 400 known species. This flexibility allows them to thrive in various ocean environments, shaping marine food webs.
Common Fish Prey
Many shark species primarily consume fish. Smaller bony fishes, such as sardines, anchovies, herrings, and mackerel, are frequently targeted. These schooling fish provide a foundational food source for various sharks. Larger predatory fish like tuna and mackerel are also common prey for some formidable sharks. The size of a shark significantly influences its prey selection, with larger species capable of hunting bigger fish.
Beyond Fish: Other Shark Diets
While fish are a common food source, many sharks expand their diets to include other marine animals. Larger species like great whites and tiger sharks frequently prey on marine mammals such as seals, sea lions, dolphins, and porpoises. Seabirds, sea turtles, and even other sharks can also become prey. Some species, like the tiger shark, have highly varied diets, sometimes consuming carrion or even man-made objects.
Some sharks have specialized dietary preferences. Hammerhead sharks, for instance, prey on stingrays, using their distinctive head shape to pin them to the seafloor. Crustaceans, including crabs, lobsters, and shrimp, are significant components of the diet for many sharks, especially smaller ones like the smooth dogfish. Mollusks such as squid and octopus are also regularly consumed. In contrast, the largest sharks, including whale sharks, basking sharks, and megamouth sharks, are filter feeders that consume microscopic plankton.
Hunting Strategies and Sensory Adaptations
Sharks possess a suite of highly developed senses that enable them to locate and capture prey. Their sense of smell is exceptionally acute, allowing some sharks to detect minute concentrations of blood from hundreds of yards away. Hearing is another powerful long-range sense, as sharks can detect low-frequency sounds from over a kilometer away. These distant cues help sharks pinpoint potential food sources before they are even visible.
The lateral line system, a series of fluid-filled canals along the shark’s head and body, detects water movements, pressure changes, and vibrations. This mechanosensory system aids in navigation, obstacle avoidance, and precise prey localization, especially in murky waters or at night. At closer ranges, sharks utilize electroreception through specialized organs called Ampullae of Lorenzini, pores concentrated around the snout. These jelly-filled canals detect weak electrical fields from muscle contractions, allowing sharks to find hidden or buried prey.
Sharks employ a variety of hunting techniques tailored to their prey and environment. Ambush predation is common, with great white sharks often attacking from below and behind. Bottom-dwelling angel sharks can bury themselves in sand or mud, waiting to snatch unsuspecting fish or crustaceans. Other sharks, like the whitetip reef shark, use a “chase and trap” method, driving prey into crevices within coral reefs before capturing them.
The thresher shark uses its elongated tail to “herd and stun” schools of fish. Hammerhead sharks use their wide, T-shaped heads to pin stingrays to the seafloor. Shark teeth are also highly specialized, adapted for seizing, cutting, or crushing different types of prey.