Hammerhead shark

Presentation

Hammerhead shark refers to a group of species in the family Sphyrnidae, recognizable by their flattened, hammer-shaped head called cephalofoil. This large marine predator inhabits tropical and warm temperate seas around the world. Its unique head morphology gives it an expanded field of vision and increased electroreceptive sensitivity to detect its prey. Several species exist, including the scalloped Hammerhead shark and the large Hammerhead shark, the latter of which can reach impressive sizes. The species is now threatened by overfishing and the demand for fins.

The body is fusiform and robust, typical of pelagic sharks, with a laterally enlarged head shaped like a hammer or shovel. This head structure carries the eyes at its ends, offering almost total panoramic vision. The skin is covered with grayish to brownish dermal denticles on the back, lighter on the belly.

Characteristics

Indicative values: they vary by subspecies, sex and region.

Habitat and distribution

The Hammerhead shark frequents the coastal and pelagic waters of tropical and subtropical seas, up to several hundred meters deep. Some species occasionally venture into lagoons and estuaries. It also likes the edges of continental shelves and seamounts.

Behaviour

This shark often adopts gregarious behavior, sometimes forming large schools that can number several hundred individuals, particularly near seamounts. It is active mainly day and night depending on the species and carries out seasonal migrations linked to water temperature and reproduction. Generally not very aggressive towards humans, it nevertheless remains a powerful predator.

Reproduction

Reproduction is viviparous, with the female giving birth to fully formed young after a gestation of several months. Litters generally number between 15 and 40 juveniles depending on the species. Nurseries are often located in shallow coastal waters, providing protection to the young from predators.

Peculiarities

The shape of the head, unique among vertebrates, acts as a hydrodynamic rudder improving maneuverability. The head extremities concentrate a high density of ampullae of Lorenzini, sensory organs detecting the electric fields of buried prey. This characteristic makes it a particularly effective hunter of rays hidden in the sand.

Threats and conservation

Overfishing, particularly for the fin trade for Asian soup, constitutes the main threat. Bycatch in industrial fishing nets also strongly affects populations. The decline of some species has led to an endangered classification by the IUCN.

References

Profile updated 28 August 2026 · Reviewed by the TunisieVet editorial team.