The Great Hammerhead Shark (Sphyrna mokarran) is the largest member of the hammerhead family, reaching lengths of over 18 feet and weights exceeding 1,000 pounds. This apex predator is recognizable by its distinct, T-shaped head structure, the cephalofoil, which provides a wide field of vision and enhanced sensory capabilities. Despite its intimidating size, the species is generally considered non-threatening to humans. This behavior reflects its specialized ecology, which directs its attention away from human interactions.
The Documented Attack Record
The statistical record concerning unprovoked attacks by the Great Hammerhead Shark is extremely low. Data compiled by the International Shark Attack File (ISAF) indicates that documented, unprovoked incidents attributed to all hammerhead species are exceedingly rare. Since records began in the 1500s, the ISAF reports only a few dozen total hammerhead incidents, none of which have resulted in a human fatality. This is significant considering the Great Hammerhead’s immense size and biting power.
Provoked vs. Unprovoked Incidents
Accurate risk assessment requires distinguishing between unprovoked incidents, where the shark initiates contact, and provoked incidents. Provoked incidents occur when the shark is antagonized or attracted by human activity, such as spearfishing. Historical data consistently demonstrates that the Great Hammerhead does not view humans as a typical food source.
Natural Behavior and Prey Selection
The biological and ecological profile of the Great Hammerhead explains its disinterest in humans as prey. Its diet is highly specialized, consisting primarily of stingrays and other batoids, bony fish, crustaceans, and smaller sharks. The shark uses its broad cephalofoil to scan the seafloor for the faint electrical fields emitted by these hidden animals, a sensory ability known as electroreception.
Observations show the Great Hammerhead may use the edge of its head to pin down prey, such as a stingray, before biting. This hunting strategy is adapted to non-mammalian, bottom-dwelling organisms. The shark’s triangular, serrated teeth are suitable for slicing through the tough hides of rays and skates. Hammerheads are often found with stingray barbs embedded in their mouths, indicating regular engagement with this venomous prey.
The species is also a solitary, nomadic, and highly migratory predator, traversing large distances along continental shelves and near-shore tropical waters. Although they inhabit areas where humans swim, their specialized hunting techniques and dietary preferences provide little incentive to pursue a human swimmer. This focus on specific marine organisms, coupled with their avoidance of novel, large objects, keeps them ecologically separated from human recreation.
Understanding Rare Human Interactions
The few documented interactions that occur with Great Hammerhead Sharks are attributed to specific circumstances rather than predatory intent. When a rare, non-fatal bite occurs, it is frequently due to investigative behavior or confusion. For example, poor visibility can cause a shark to mistake a human’s silhouette or movement for its natural prey.
Most documented incidents involving large sharks occur when the animal is surprised, provoked, or reacting to a threat. Actions such as spearfishing, which introduces struggling fish and blood into the water, can draw predators into an excited state. In these rare instances, contact is generally an exploratory bite or a defensive reaction, not a sustained feeding attack targeting a primary food source.