Known as: Scalloped Hammerhead, Kidney-headed hammerhead, bronze hammerhead, southern hammerhead
Estimated numbers left in the wild: Unknown.
The scalloped hammerhead is a large, slender shark ranging from 3.7 meters to 4.3 meters in length, with a top weight of 150 kilograms. The shark is bronze coloured on top and white below, but its most identifying feature is the “hammer head.” The animal’s head is flattened and extended outwards in both directions, giving the front of the creature an unmistakeable T shape. In the case of the scalloped hammerhead, the head also includes a number of lengthwise grooves in the flesh, which explains the species name.
This shark ventures close inshore in shallow coastal waters, but also lives in the deeper water further offshore. A depth of 275 meters is acceptable and this hammerhead will go as deep as 500 meters or so, though it avoids the open ocean. The wide, flattened head spreads out a series of electrically sensitive organs called the ampullae of Lorenzini, which can detect the presence of prey even in darkened or murky waters. This large predatory fish prefers medium-small prey that can be consumed entirely rather than being bitten to pieces, due to the structure of its mouth. Fish naturally top the list of prey species, but the shark also consumes large numbers of squid, octopus, crustaceans such as crabs and lobsters, rays, and small shark species or juveniles.
Like many sharks, this hammerhead gives birth to live pups, which are nourished with an egg yolk placenta while developing inside their mother. Gestation is approximately one year, and up to 40 pups may be born to a single female. The young fish are 30 to 60 centimetres long at birth, and remain inshore, though close to the bottom, until they grow larger. These hammerheads will opportunistically consume juveniles of their own species, but most mortality is due to other species of sharks. The natural lifespan of the shark is 30 years, possibly more.
Location: A truly global animal, the scalloped hammerhead frequents most coastal waters from 46 degrees north to 36 degrees south. It is found along the eastern coasts of North America, Central America, and South America, the east and west coasts of Africa, throughout the Middle Eastern waters, the Indian Ocean, around Australia, and up the coast of China to Japan. This large shark prefers shallow water but can be found at depths up to 500 meters also.
Threats: Overfishing of this shark species is the principle hazard to its long-term survival, with this occurring in many areas where these animals are found. The insatiable demand of the Asian market for shark fins has driven the price of these as high as $50 per pound or more, creating a massive economic incentive flout laws and circumvent protective measures. Furthermore, the scalloped hammerhead has large, desirable fins, making it a primary target for finning.
Conservation efforts: There are no organized conservation measures in place for this species, and its protection under the law is weak to non-existent and indirect.
Scalloped Hammerhead Videos
Oceana is the largest international organization focused only on ocean conservation, protecting marine ecosystems and endangered species such as the Scalloped Hammerhead.