The Great Hammerhead Shark (Sphyrna mokarran) is the largest species of hammerhead with the largest ever recorded being more than six metres in length! These fish can be found in tropical and warm temperate marine waters worldwide, spending a lot of their time around reefs.
Average Adult Size: | 4.6 Metres Long |
Diet: | Carnivore |
Lifespan: | 20 - 30 Years |
Natural Habitat: | Tropical Marine Reefs |
ICUN Red List Rating: | Critically Endangered (CR) (2019) |
Description:
The Great Hammerhead shares its streamlined body and cephalofoil with other hammerheads, although the cephalofoil of the Great Hammerhead has an almost straight front margin with prominent medial and lateral indentations. This species also has a very distinctive sickle-shaped dorsal fin.
These sharks are generally grey-blue in colour, with a white underside. They grow to around 4.6 metres on average with males of this species typically staying smaller than females. The largest Great Hammerhead found was just over six metres long.
Habitat:
Great Hammerheads can be found inhabiting tropical waters around the world. They can be found off the coast in waters just one metre deep to depths of eighty metres offshore.
They prefer to roam coral reefs but can also be found in deeper waters near land and continental shelves. They are migratory, with populations off the coast of Florida moving further towards the poles during the summer months.
Diet and Feeding:
These sharks are active predators who feed on a variety of prey including invertebrates, bony fish, and smaller sharks. They have also been known to be cannibalistic and are specialists at feeding on other sharks, rays, and skates - especially stingrays, their venomous spines are often found lodged in the mouth of hammerheads but it doesn't seem to bother them.
They primarily hunt at dusk and dawn by swinging their heads in broad motions across the seabed to pick up electrical signals from stingrays buried in the sand. Once they've found a ray, their cephalofoil allows them to turn around quickly and attack the ray.
Breeding:
Great Hammerhead Sharks are viviparous, which means the embryo develops inside the body of the mother who then gives birth to live young. Unlike most other shark species that breed on or near the ocean floor, Great Hammerheads have been spotted mating near the surface of the water.
Females breed once every two years with their gestation period lasting for 11 months. They can give birth to anywhere from 6 to 55 pups but 20 to 40 is typical. The young measure 50 to 70 centimetres long.
Conservation:
Assessment of the Great Hammerhead's conservation status is difficult as most fisheries don't separate the Great Hammerhead from other hammerhead species when reporting catches. As of 2019, they are listed as critically endangered on the IUCN Red List.
There are currently no conservation measures specifically protecting the Great Hammerhead. Some countries are beginning to ban shark finning which should help to protect this species.