Hammerhead sharks (lat. Sphynidae) are in fact not a single shark species, but rather a collective term for a sub-species, or genus, of shark.
They count nine different sharks, though there is still some debate of the exact number of unique genera.
Common for all of them is the unique head shape from which they get their English name; a wide, large head structure resembling hammer’s head.
Unlike most sharks, most hammerheads are schooling sharks during the day, becoming solitary only at night. The most common hammerheads for divers to encounter are the Great Hammerhead and the Scalloped Hammerhead.
This article will focus on the the Great Hammerhead Shark (Sphyrna mokarran).
The main distinguishing features of all hammerheads are of course their heads, which are flattened and extended sideways, generating a unique head shape.
The eyes of the shark are on the tips of the sides of the head, and the mouths, which are typically comparatively small mouth on the underside of the head.
The Great Hammerhead can be recognized from the other hammerhead sharks by the shape of its head, which has a straight front line rather than the curved shape of other hammerheads, and by its large dorsal fin.
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Unlike the other species of hammerheads, this shark is a solitary hunter. It is a large shark, reaching lengths of up to 6 meters.
As with most hammerheads, its body is comparatively slender for a shark of its size.
Where to see it
The Great Hammerhead lives in coastal areas in tropical and warm waters all around the world, in a wide belt on both sides of the equator.
It is often found on or near coral reefs, but due to its solitary and shy nature, it is often hard to find. The sensory apparatus of this shark, as with many of other sharks, is so acute that they are aware of divers in the water long before the divers are within visual range of the shark. This can cause the shark to simply swim off.
One location known to very often see Great Hammerheads is Bimini Island in the Bahamas, as well as other destinations in the area.
When to see it
The sharks are migratory, and individuals close to the equator have been known to migrate further north and south in the summer time.
So in the summer months, the chances of seeing them in the northern and southern areas of their habitat increase (including the United States and the Gulf of Mexico, Australia, Japan, and the Red Sea), whereas destinations around the Equator hold the biggest chance of sightings in the winter months.
Interactions with humans
Generally a very shy animal, Great Hammerheads tend to swim off at the presence of humans. However, they have been known to become very inquisitive, though, and reports of them coming very close to divers are quite frequent. However, while the shark is potentially dangerous to humans, actual attacks are rare.
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But, as with any shark of this size and strength, it should be treated with the utmost respect.
The large dorsal fin of the Great Hammerhead is one of the preferred fins for shark fin’s soup, and as a result of this, the shark has been fished heavily, especially in Asia. This has brought the shark to a point of Endangered, according to the IUCN Red List.
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The one feature of the shark that works to its advantage, in terms of species survival, is its reproductive pattern, where they give birth to a relatively large number of pups, with 20-40 being normal.
Have you ever encountered a Hammerhead Shark? Let us know where you saw it, in a comment below!