Marine Wildlife Encyclopedia
Scalloped Hammerhead Shark Sphyrna lewini
Along with the seven other known species of hammerhead sharks, the scalloped hammerhead has a strange, flattened, T-shaped head. In this species, the front of the head has three notches, which produces the scalloped shape from which it takes its name.
The eyes are located at the sides of the head. Hunting near the seabed, the shark swings its head from side to side, looking for prey such as fish, other sharks, octopus, and crustaceans, and using sensory pits on its head to detect the electrical fields of buried prey such as rays. The head may also function as an airfoil, giving the shark lift and helping it to twist and turn as it chases its prey.
Scalloped hammerheads may be seen in large shoals of over a hundred individuals. They give birth to live young in shallow bays and estuaries, where the skin of the young darkens to give protection against sunlight.
The fins of the scalloped hammerhead are extremely valuable for use in shark fin soup and the scalloped hammerhead is taken both as a target species and as bycatch with pelagic longlines, fixed bottom longlines, nets and pelagic trawls. The meat, skin and oil are also utilized. The scalloped hammerhead has declined by more than 75 percent in the past 15 years along the eastern U.S. and is listed as “Endangered” on the IUCN Red List.
The decline of the scalloped hammerhead, and other great sharks in the Atlantic, has led to an increase in the cownose ray population which resulted in a collapse of the century-old North Carolina bay scallop industry. Oceana’s Predators as Prey report details this cascading effect and other important impacts the loss of sharks will have on the marine ecosystem.
What Oceana Does
Oceana is working internationally to protect and restore shark populations. Through policy, science, legal and communications work, Oceana is pushing for true shark finning bans, species-specific shark management and reduced shark bycatch.