Great Hammerhead Shark

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Unlike many sharks, great hammerheads are specially adapted with their broad flatten head shape to help pin stingrays to the bottom, aiding in feeding. Also, their fins are highly prized in the shark-fin trade, which is a major threat. Populations have declined by more than ~80% over ~70 years in some regions.

The great hammerhead is the largest hammerhead species. It has a distinctive “hammer” (cephalofoil) that is nearly straight across the front, with a shallow notch in the centre. Its first dorsal fin is tall and falcate (curved), pelvic fins also have curved edges. Colour tends to be brownish to light grey or olive above, white below. It can reach ~4.6 m on average and up to ~6.2 m in some cases.

Apex predator: feeds on rays (including burying stingrays with its hammer), bony fishes, cephalopods, smaller sharks. Solitary in many cases, migratory; long gestation, slow growth, relatively low reproductive rate. Because of low reproduction and late maturity, especially vulnerable to overfishing.

Where divers may encounter it
Dive sites in Bahamas, some Caribbean locations, Indian Ocean reefs, occasionally off shore in Indo-Pacific islands, around continental shelf edges, shallow reefs where prey (rays, fishes) abundant.

Diving tips
Stay at a respectful distance; these sharks are large and often shy. Do not provoke, avoid sudden movements. Dive early in the day or around feeding times may increase chance of sighting. Good dive operators often monitor where great hammerheads pass through migration routes.

Critically Endangered. Population trend: decreasing. Listed in CITES Appendix II, etc.

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