The hammerhead shark family (Sphyrnidae) is immediately recognizable by its distinctively flattened and laterally expanded head structure. This unusual anatomy, called a cephalofoil, sets them apart from all other shark species. While all nine recognized species share this unique feature, their sizes vary greatly. Public interest often centers on identifying the largest of these peculiar predators.
Identifying the Great Hammerhead
The largest species within the hammerhead family is the Great Hammerhead (Sphyrna mokarran). This massive predator is easily distinguished from relatives, such as the Scalloped Hammerhead, by its characteristic cephalofoil, which features a nearly straight front margin. The maximum recorded length for an individual reaches up to 6.1 meters (20 feet).
The most massive specimens are typically pregnant females, which grow larger than males. One of the heaviest individuals ever recorded weighed up to 580 kilograms (1,280 pounds). A mature adult typically measures between 3.5 and 4.6 meters in length, with a common weight range from 200 to 500 kilograms. This sheer bulk, combined with a tall, sickle-shaped first dorsal fin, establishes the Great Hammerhead as the undisputed giant among its kind.
The Purpose of the Cephalofoil
The hammer-shaped cephalofoil is a highly evolved sensory and hunting tool. The expanded surface area is densely covered with tiny pores containing electroreceptor organs known as the Ampullae of Lorenzini. Spreading these sensory organs across a wider area allows the shark to detect the faint electrical fields generated by the muscle movements of buried prey. This provides enhanced precision during the hunt.
This electrosensory advantage allows the Great Hammerhead to sweep a broad area of the seafloor, efficiently locating bottom-dwelling animals hidden beneath the sand. The cephalofoil also serves a direct mechanical purpose during the hunt, particularly when pursuing its favored food source, the stingray. Observations suggest the shark uses the side of its hammer to strike and pin the ray against the substrate. This action effectively immobilizes the prey before consumption.
Habitat and Prey
The Great Hammerhead is a highly migratory species found globally in warm temperate and tropical waters. Their habitat ranges from coastal areas and shallow lagoons to the deeper waters over continental shelves and near island terraces, occasionally diving to depths of 300 meters. These movements can cover vast stretches of ocean. Some individuals have been documented traveling over 1,200 kilometers in a period of two months.
As an apex predator, the Great Hammerhead maintains a diverse diet, including bony fish, squid, and smaller sharks. Its most notable prey is rays and skates, which it pursues relentlessly on the ocean floor. The shark has developed a tolerance for the venomous spines of stingrays, often found embedded in its mouth, indicating these heavily defended creatures are a regular part of its meals.
Conservation Status
Despite its impressive size and status as an apex predator, the Great Hammerhead is highly vulnerable to human activities. The International Union for Conservation of Nature (IUCN) has assessed the species as Critically Endangered globally. This classification results from significant population decline driven by overfishing and the species’ inherently slow reproductive rate.
The shark is targeted both intentionally and accidentally in commercial fisheries across the globe. Its large, valuable fins make it a prime target for the international shark fin trade. Its coastal habitat and migratory routes also increase its risk of being caught as bycatch in gear such as longlines and gillnets. These combined pressures contribute to its high mortality rate, making the Great Hammerhead one of the most threatened shark species.