Hammerhead sharks are formidable marine predators. Their unique anatomy and diverse feeding strategies allow them to capture a wide range of prey. Understanding their diet provides insight into their ecological role within marine ecosystems.
Main Prey Items
Hammerhead sharks consume a wide variety of marine animals, including various fish, cephalopods, and crustaceans. Their diet often includes schooling fish such as sardines, mackerel, and jacks, which they can efficiently target. Cephalopods like squid and octopus are also common food sources for these agile hunters. Smaller hammerhead species frequently feed on crabs, shrimp, and other bottom-dwelling invertebrates.
Stingrays are a particularly favored prey item for many hammerhead species, especially the large great hammerhead. These sharks are adept at finding stingrays, which often bury themselves in the sand. Besides rays, larger hammerheads also eat other sharks, including their own kind, and various bony fish like groupers and sea catfish. This broad diet highlights their opportunistic feeding habits.
Specialized Hunting Techniques
The hammer-shaped head, or cephalofoil, offers unique hunting advantages. This wide head significantly enhances their sensory perception, particularly their electrosensitivity. Thousands of specialized pores called ampullae of Lorenzini are spread across the cephalofoil, allowing the shark to detect the faint electrical impulses generated by hidden prey, even those buried beneath the sand. This sensory capability is akin to a built-in metal detector, enabling them to locate camouflaged animals.
Hammerheads also use their broad heads as a physical tool during hunting. They can use the cephalofoil to pin down prey, such as stingrays, against the seafloor. This technique helps to immobilize the prey, making it easier for the shark to consume. The wide-set eyes on the ends of the cephalofoil also provide an expansive field of vision, including some binocular vision, aiding in judging distances. The head shape enhances their sense of smell, as wide-set nostrils allow for more effective scent detection.
Dietary Differences Among Hammerhead Species
The diet of hammerhead sharks varies considerably among the different species, influenced by factors such as their size, habitat, and geographical location. The great hammerhead, being the largest species, has a diet that includes substantial prey like large rays and even other sharks. They are known for their ability to consume other sharks.
In contrast, the smaller bonnethead shark exhibits a more diverse, even omnivorous, diet. These sharks primarily feed on crustaceans such as crabs and shrimp, along with bivalves and snails. Uniquely among sharks, the bonnethead also consumes significant amounts of seagrass. Their tooth structure is adapted for this varied diet, featuring small, sharp teeth for grasping and broad, flat teeth for crushing hard-shelled prey.
The scalloped hammerhead shark is a generalist predator, consuming whatever is abundant in its environment. Their diet includes bony fish, cephalopods, and crustaceans, and can also extend to stingrays and other sharks. The diet of scalloped hammerheads can vary with age, with juveniles typically focusing on smaller inshore fish and shrimp, while adults incorporate larger organisms found in deeper waters.