The largest hammerhead, with a tall first dorsal fin and a nearly straight head margin. Solitary, unlike the scalloped hammerhead.
To about 5.5 m, the largest of the hammerheads. Two characters separate it from the scalloped hammerhead, and both are visible: the front margin of the head is almost straight with a notch in the middle, where the scalloped’s is curved and scalloped along its length; and the first dorsal fin is very tall and strongly curved, where the scalloped’s is shorter. It is also solitary, and the scalloped hammerhead schools.
The head is a sensory platform rather than a rudder. It spreads the ampullae of Lorenzini over a wider area and gives a wider field of view, and the animal uses it directly on stingrays, pinning them to the bottom with it while it bites. In the western Atlantic the reliable sighting is off Bimini in the Bahamas in winter, in a few metres of water over sand, on baited dives. Elsewhere on this site it is an occasional animal at a channel mouth or over a deep reef. It is listed as critically endangered and it survives poorly after being caught and released, which is worth knowing before supporting any fishery for it.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.