The hammerhead shark (Sphyrnidae) is a species of shark found worldwide in warm waters or continental shelves. The hammerhead has a strange T-shaped head with eyes on each side of the head. A theory has been advanced that the hammer-like shape of the head may have evolved (at least in part) to enhance the animal’s vision. Unlike most sharks, hammerheads usually swim in schools during the day, becoming solitary hunters at night.
The known species range from 0.9 to 6.0m in length and weigh from 3 to 580kg. They are usually light gray and have a greenish tint. Their bellies are white which allows them to blend into the ocean when viewed from the bottom and sneak up on their prey. Their heads have lateral projections which give them a hammer-like shape. Hammerheads have disproportionately small mouths and seem to do a lot of bottom-hunting. They are also known to form schools during the day, sometimes in groups of over 100. In the evening, like other sharks, they become solitary hunters. During the summer, they participate in a mass migration to search for cooler waters.
Hammerhead sharks are known to eat a large range of prey such as fish (including other sharks), squid, octopus, and crustaceans. Stingrays are a particular favorite. These sharks are often found swimming along the bottom of the ocean, stalking their prey. Their unique heads are used as a weapon when hunting down prey. The hammerhead shark uses its head to pin down stingrays and eats the ray when the ray is weak and in shock. The great hammerhead, tending to be larger and more aggressive than most hammerheads, occasionally engages in cannibalism, eating other hammerhead sharks, including its own young. In addition to the typical animal prey, bonnetheads have been found to feed on seagrass. They may swallow it unintentionally, but they are able to partially digest it. This is the only known case of a potentially omnivorous species of shark.
According to the International Shark Attack File (ISAF), humans have been subject to 17 documented, unprovoked attacks by hammerhead sharks within the genus Sphyrna since 1580 AD, none of which were fatal.
In native Hawaiian culture, sharks are considered to be gods of the sea, protectors of humans, and cleaners of excessive ocean life. Some of these sharks are believed to be family members who died and have been reincarnated into shark form. However, some sharks are considered man-eaters, also known as niuhi. These sharks include great white sharks, tiger sharks, and bull sharks. The hammerhead shark, also known as mano kihikihi, is not considered a man-eater or niuhi, it is considered to be one of the most respected sharks of the ocean, an aumakua. According to Wikipedia, “any Hawaiian families believe that they have an aumakua watching over them and protecting them from the niuhi. The hammerhead shark is thought to be the birth animal of some children. Hawaiian children who are born with the hammerhead shark as an animal sign are believed to be warriors and are meant to sail the oceans. Hammerhead sharks rarely pass through the waters of Maui, but many Maui natives believe that their swimming by is a sign that the gods are watching over the families, and the oceans are clean and balanced.”