General Overview
The Sphyrnidae family, commonly known as hammerhead sharks, includes about nine species characterized by their unique, flattened, hammer-shaped heads. Found in warm temperate and tropical oceans worldwide, these sharks are highly distinctive predators. Their unusual head structure, called a cephalofoil, gives them enhanced sensory perception and maneuverability, making them among the most specialized sharks in the ocean.
Appearance
Hammerheads range in size from the small bonnethead (Sphyrna tiburo), about 1.5 m long, to the great hammerhead (Sphyrna mokarran), which can exceed 6 m. Their most striking feature is the laterally expanded head with eyes and nostrils positioned at the tips. This cephalofoil provides a wide visual field and improves electroreception through the ampullae of Lorenzini, aiding in detecting prey hidden in sand. Body coloration is generally gray to olive-brown above with lighter undersides, providing countershading for camouflage.
Diet
Hammerhead sharks are carnivorous, feeding on a variety of prey including fish, squid, octopuses, crustaceans, and other sharks. Some species, such as the great hammerhead, specialize in hunting stingrays, which they pin to the seafloor with their wide heads before biting. Smaller species, like the bonnethead, also consume seagrass, making them one of the few known omnivorous sharks.
Habitat
Hammerheads are found in warm coastal waters, continental shelves, and along seamounts, with some species preferring shallow areas and others venturing into the open ocean. They often migrate seasonally, moving toward cooler waters during summer months. Juveniles are commonly found in shallow coastal nurseries, which provide protection from larger predators.
Behavior
Hammerheads are generally more social than many other sharks, with some species forming schools of dozens to hundreds of individuals, particularly during the day. These schools may provide protection and aid in navigation. At night, they often disperse to hunt individually. They are strong, agile swimmers and rely on their enhanced sensory capabilities for hunting. Hammerheads are viviparous, giving birth to live young after a gestation period of 9–12 months.
