4847 x 3799 px | 41 x 32,2 cm | 16,2 x 12,7 inches | 300dpi
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hammerhead sharks are a group of sharks in the family Sphyrnidae, so named for the unusual and distinctive structure of their heads, which are flattened and laterally extended into a "hammer" shape called a "cephalofoil". Most hammerhead species are placed in the genus Sphyrna; some authorities place the winghead shark in its own genus, Eusphyra. Many, not necessarily mutually exclusive, functions have been proposed for the cephalofoil, including sensory reception, maneuvering, and prey manipulation. Hammerheads are found worldwide in warmer waters along coastlines and continental shelves. The nine known species of hammerhead range from 0.9 to 6 m long (3 to 20 feet). All the species have a projection on each side of the head that gives it a resemblance to a flattened hammer. The shark's eyes and nostrils are at the tips of the extensions. The hammer shape of the head was thought to help sharks find food, aiding in close-quarters maneuverability and allowing the shark to turn sharply without losing stability. However, it was found that the special design of its vertebrae allowed it to make the turns correctly, more than its head. But as a wing the hammer would also provide lift; hammerheads are one of the most negatively buoyant of sharks. Like all sharks, hammerheads have electroreceptory sensory pores called ampullae of Lorenzini. By distributing the receptors over a wider area, hammerheads can sweep for prey more effectively. These sharks have been able to detect an electrical signal of half a billionth of a volt. The hammer-shaped head also gives these sharks larger nasal tracts, increasing the chance of finding a particle in the water by at least 10 times as against the ability of other 'classical' sharks. Wider spacing between sensory organs better enables an organism to detect gradients and therefore the location of a gradient source such as food or a mate. The peculiar head of this shark can be thought of as analogous to the antennae of an insect.
