The hammerhead shark, instantly recognizable by its flattened, wide head structure known as the cephalofoil, is one of the ocean’s most specialized predators. This unique anatomy has long fueled speculation about the shark’s diet and its place in the marine food web. Hammerheads are powerful, active hunters, and their reputation as an apex predator often leads to the question of whether they prey on other shark species.
Hammerhead Predation: Do They Eat Other Sharks?
Hammerhead sharks, particularly the largest species like the Great Hammerhead (Sphyrna mokarran), do consume other sharks, but this behavior is secondary to their primary diet. They are opportunistic feeders, taking advantage of vulnerable prey, including smaller or injured sharks. The energetic reward of a large, high-calorie meal can outweigh the effort and risk involved in the hunt.
This predatory behavior also extends to cannibalism among the larger hammerhead species. Great Hammerheads are known to prey on smaller or juvenile members of their own kind. This behavior reflects the Great Hammerhead’s aggressive nature and is sometimes tied to resource scarcity.
Scientific modeling suggests that a large Great Hammerhead, weighing around 250 pounds, could sustain itself for approximately three weeks by eating a single 55-pound Blacktip shark. While this demonstrates the energetic benefit of such a large prey item, the consumption of other sharks is not a daily occurrence. It is an opportunistic strategy that supplements their more reliably sourced diet of bottom-dwelling organisms.
The Staple Diet: Preferred Prey Items
The vast majority of the hammerhead shark’s diet is composed of teleost (bony) fishes, crustaceans, and rays. Stingrays and skates are a particular favorite, often making up a substantial portion of the stomach contents in species like the Great Hammerhead. One study found digested stingray remnants in the stomachs of over 80% of Great Hammerheads examined off the coast of Natal, South Africa.
Hammerheads hunt for these bottom-dwelling animals, which often bury themselves in the sand for camouflage. Common bony fish prey include sea bass, sardines, and mackerel, depending on the shark’s geographic location. They also consume cephalopods, such as squid and octopus.
Smaller species, such as the Bonnethead shark (Sphyrna tiburo), exhibit a varied diet that includes mollusks and crustaceans. Uniquely among sharks, the Bonnethead has been found to consume and partially digest seagrass, which can constitute up to half of its stomach contents. This makes the Bonnethead an omnivore, illustrating the diversity in feeding habits across the hammerhead family.
Feeding Strategy and the Role of the Cephalofoil
The unique cephalofoil plays a direct and functional role in the hammerhead’s specialized feeding strategy. The wide structure acts as a massive sensory sweep, allowing the shark to effectively scan the seafloor for hidden prey. This is possible because the cephalofoil houses a high concentration of specialized electroreceptors called the Ampullae of Lorenzini.
These sensory organs detect the minute electrical fields generated by the muscle movements of living organisms, even those concealed beneath the sand. By spreading these receptors across a much wider surface area than other sharks, the hammerhead achieves superior electroreception. This enhanced capability allows them to locate rays and other prey that are otherwise invisible to the eye.
Once a ray is located, the hammerhead uses its cephalofoil as a physical tool. The shark reportedly uses the side of its head to pin the ray against the seabed, immobilizing the venomous prey. This pinning maneuver allows the hammerhead to deliver a non-lethal bite to the ray’s wing or disk, tiring and subduing the animal before consuming it.