Critically Endangered
Great hammerhead
Sphyrna mokarran
Great hammerhead is a shark or ray in the family Sphyrnidae (order Carcharhiniformes) — Sphyrna mokarran, recorded as Critically Endangered.
Appearance
The second dorsal fin and anal fin are both relatively large, with deep notches in the rear margins. The great hammerhead is dark brown to light gray to olive above, fading to white on the underside. The fins are unmarked in adults, while the tip of the second dorsal fin may be dark in juveniles.
The width of the cephalofoil is 23–27% of the body length. The typical minimum great hammerhead measures 3.5 m (11 ft) long and weighs over 230 kg (510 lb), while the maximum measures 4.6 m (15 ft) long and weighs 449.5 kg (991 lb).
Range and habitat
The great hammerhead inhabits tropical waters around the world, between the latitudes of 40°N and 37°S. In the Atlantic Ocean, it is found from North Carolina to Uruguay, among them the Gulf of Mexico and the Caribbean Sea, and from Morocco to Senegal, and the Mediterranean Sea. It is found all along the rim of the Indian Ocean, and in the Pacific Ocean from the Ryukyu Islands to Australia, New Caledonia, and French Polynesia, and from southern Baja California to Peru.
Pins are Wikidata “endemic to” fields. Orange dots, when present, are GBIF occurrence tiles — survey bias included.
Diet
The great hammerhead is a solitary, nomadic predator that tends to be given a wide berth by other reef sharks. The great hammerhead shark is an active predator with a varied diet.
Known prey of the great hammerhead include invertebrates such as crabs, lobsters, squid, and octopus. Bony fishes such as tarpon, sardines, sea catfishes, toadfish, porgies, grunts, jacks, croakers, groupers, flatfishes, boxfishes, and porcupine fishes, and smaller sharks such as smoothhounds. At Rangiroa Atoll, great hammerheads prey opportunistically on grey reef sharks (Carcharhinus amblyrhynchos) that have exhausted themselves pursuing mates.
In crisis
A solitary, strong-swimming apex predator, the great hammerhead feeds on a wide variety of prey ranging from crustaceans and cephalopods, to bony fish, to smaller sharks. As a result, great hammerhead populations are declining substantially worldwide, and it has been assessed as critically endangered by the International Union for Conservation of Nature (IUCN) as of 2019. This species is listed as globally critically endangered on the IUCN Red List.
It is endangered in the north-western Atlantic and the Gulf of Mexico, where though it is not a targeted species, populations have dropped 50% since the 1990s due to bycatch. It is also endangered in the southwestern Indian Ocean, where large numbers of longline vessels operate illegally along the coasts for hammerheads and the giant guitarfish (Rhynchobatus djiddensis).
CITES lists this taxon on Appendix II. Confirm the current appendix on the CITES checklist.
Great hammerhead is Critically Endangered on this catalog because that is the IUCN category stored on Wikidata. Confirm the official criteria and any later count on iucnredlist.org.
Sources
Written for this catalog from the English Wikipedia article on Great hammerhead, Wikidata item Q757353. Family and order context is original field-guide writing about the group, not a copied assessment of this one species. Wikipedia text is CC BY-SA. Not an IUCN assessment. Counts, when quoted, can change — confirm them on the recovery programme and on iucnredlist.org.
