Great Hammerhead Shark
The largest of the hammerhead sharks
The Great Hammerhead shark (Sphyrna mokarran) is the largest species of Hammerhead shark, belonging to the family Sphyrnidae, attaining a maximum length of 20 feet. It is found in tropical and warm temperate waters worldwide, inhabiting coastal areas and the continental shelf. The Great Hammerhead shark can be distinguished from other Hammerheads by the shape of its cephalofoil. It is wide with an almost straight front margin. It is also distinguished by its tall and sickle-shaped first dorsal fin. The Great Hammerhead shark is one of the most wondrous and graceful sharks that we have had the pleasure of diving with. We have been lucky enough to see theme right here in Jupiter, Florida and in Bimini, Bahamas. Check out one of our recent dives here.
(After their flat-headed appearance)
The largest of the Hammerhead, Sphyrnidae family
Status: IUCN Red List Endangered
Average Size and Length: 16 – 20 ft.
Average Weight: 550-800 pounds. There are some undocumented accounts of one averaging 1000 pounds.
Current Rare Mythical Sightings: Largest called Old Hitler between Jupiter, Florida and Bimini, Bahamas. Want to see a Great Hammerhead in action? Check out our latest trip by watching this video!
Teeth and Jaw: Triangular in shape with serrated markings along the edges. They are wider in the upper jaw than the lower jaw. There are about 25 in each jaw. Smaller mouth and jaw, under and just below the cephalofoil. Check out this video.
Head: Cephalofoil. What sets the Great Hammerhead shark apart from other sharks, is that the cephalofoil gives the ampullae of Lorenzini a much greater area of coverage. Several hypotheses are proposed to explain the evolution of the sphyrnid cephalofoil but few have been empirically tested. Some suggest the cephalofoil acts like a canard to provide hydrodynamic lift and increase maneuvering capabilities. Another hypothesis is that the cephalofoil functions in prey manipulation. Other hypotheses involve potential advantages of spacing sensory structures across the surface or at the lateral ends of the cephalofoil.
Demographic, Habitat, Environment and Range: Surface down to between 300 and 1000 feet. Coastal-pelagic and semi-oceanic, mainly offshore, but also coastal areas, reefs and estuaries to feed. Hot location for sightings is Bimini, Bahamas. Other areas include Jupiter, Florida, but Great Hammerhead sharks mainly stay in sub-tropical to warm, temperate tropical climate regions hugging the shore of every continent in every ocean. Great Hammerhead sharks migrate to higher latitudes in summer and return to tropics during the winter. Nomadic and seasonal.
Diet: Prefers stingrays. They can actually eat the barbed tail. Its cephalofoil is naturally designed to detect stingrays on the ocean floor. They also eat a wide range of fish from Jacks, Groupers, flatfishes, Squid, Octopus, and crustaceans.
Ram-Suction Index: Predominately ram. Fatal first bite to immobilize prey.
Aesthetic Identification: Great Hammerhead sharks, like all Hammerhead sharks have the ability to tan in the sun. Great Hammerhead sharks are greyish-brown to olive-green on the back and are pale white on its underside and belly. Counter shaded for camouflage and protection. Its fins are unmarked. Very large hammerhead with a notch at the center of the head. The first dorsal fin is high and curved and the second dorsal and pelvic fins are high with deeply concave indentations in the rear.
Biology: Males reach sexual maturity between 7-8 feet and females 8-9 feet. They mate during spring and summer. They have been rarely witnessed mating but when observed, it has been at the surface. Males have two external claspers. They are viviparous, and gestation is 11 months long. Great Hammerhead sharks can have litters anywhere from as few as 6 pups to as many as 42 pups. They can be cannibalistic. Scientists believe their life span is about 35 years, but there is current and ongoing research about their lifespan. The persistence of the sphyrnid cephalofoil over the past 20-25 million years and its presence in several hammerhead shark species of diverse head morphologies tell of its evolutionary success.
Unique Body Structure: Have you watch our videos of the Great Hammerhead sharks’ swimming? They appear to glide more gracefully than other sharks. It is memorizing to watch them. Great Hammerhead sharks are actually more maneuverable than other sharks. Hammerhead sharks are more flexible than carcharhinids, and that this flexibility seems due to cross sectional shape rather than number of vertebrae.
Sensing and Intelligence: The Great Hammerhead shark has one of the largest brains in the shark world, and it is highly designed and evolved specific to its habits and environment and is highly intelligent. The Great hammerhead is the most recently evolved species of shark.
Great Hammerhead sharks rely on their lateral line and their ampullae of Lorenzini but are unique. Because of its large cephalofoil, Great Hammerhead sharks have much more ampullae over a greater surface area than other sharks, over 3000 pores. Their eyes are spaced far apart, on either side of the cephalofoil, and therefore do have greater blind spots, but in turn this give them a full 360-degree view with just the turn of its head, and 180 degree with one eye scanning. In low light a hammerhead shark can see 10 times better than a human could.
Low pitched sounds are easiest for sharks to pick up, and hammerheads can hear low sounds that humans can’t.
The Great Hammerhead shark’s sense of smell is one of the most important, and a shark can detect a teaspoon of blood in an Olympic sized swimming pool. Hammerhead sharks have two nasal cavities called nares, which each have an entry and exit openings.
Their sense of taste is the least developed of all of their senses.
Behavioral Traits: For communication, Great Hammerheads use body language for establishing the social hierarchy and giving orders for the schools to disperse. Head shakes, torso thrusts and swimming in loops are some of the body language signals by these sharks. Great Hammerheads are mostly nocturnal, meaning they are most active during the evening.
Bridging large travelling distances, the great hammerhead swims on one of its sides. This swimming method is called rolled swimming, where the shark rolls to its side and continues swimming forward. This posture reduces drag and conserves energy while the large dorsal fin is used to obtain lift. Great hammerheads may use the rolled swimming method very often in order to keep their energy consumption rate under control.
Great hammerheads are solitary predators. However, they have been spotted also in large groups during migration periods in summer. They are generally shy sharks, especially near humans.
Speed: Bursts up to 25 mph. The bite force is 2400 N in the great hammerhead (Sphyrna mokarran) (581-kg body mass) (Habegger et al., 2012).
Great Hammerhead Future and Conservation:
Great Hammerhead Recorded Attacks on Humans: