Hammerhead Shark Facts

The Hollywood movie Jaws, featuring a shark, aroused fear in people all over the world. People really believed that these sharks are as murderous as it was shown in the movie. Many of these, including hammerheads, were hunted and killed, as fear took the form of hate killing. How about separating fiction and truth, by going through the hammerhead shark facts to learn about these fish? There are nine types of hammerhead sharks. They are listed below:

• Scalloped hammerhead
• Great hammerhead
• Smooth hammerhead
• Whitefin hammerhead
• Scalloped bonnethead
• Winghead shark (genus Eusphyra)
• Scoophead hammerhead
• Bonnethead or shovelhead hammerhead
• Smalleye hammerhead

Information about the Hammerheads

Scientific Information
Kingdom	Animalia
Phylum	Chordata
Class	Chondrichthyes
Order	Carcharhiniformes
Family	Sphyrnidae
Genus	Sphyrna and Eusphyra

Although hammerhead sharks live in herds or schools, when it comes to food, they hunt alone in the dark. The herd strength can be as big as 10-20 hammerheads per school. On one rare occasion, off the coast of Australia, the herd was reported to be consisting of approximately, 200 hammerheads.

• Hammerhead sharks have acquired their name because of the distinct shape of their head.
• The head is flat, laterally extended and resembles a flattened hammer which, by acting as a wing or a flat surface, puts the fish at advantage when it comes to close quarter maneuvers. Such a structure is called a cephalofoil.
• Some scientists say that the shape of the head evolved slowly over numerous generations, but there are others who believe that it is due to mutation that proved profitable to the hammerheads.
• Eyes, in hammerheads, are located at the end of the lateral part of the head. These wide-set eyes improve their ability to see and locate their prey in the murky waters of the sea.
• In addition to the eyes, they use a specialized sensory organs referred to as the ampullae of Lorenzini, to detect the electrical field generated around their prey's body. This organ is so sensitive that it allows them to locate even small fish such as groupers, jacks, catfish, toadfish, boxfish and herring.
• Their food also includes cownose rays, guitarfish, eagle rays, butterfly rays, whiptail stingrays, octopuses, skates, squid, and crustaceans such as shrimp, mantis shrimp and crabs. Stingrays, when they sense a predator, bury and hide themselves under the sand at the bottom of sea, but the field generated by the electrical activities in their bodies gives them away to hammerheads.
• It is believed that they can also receive and transmit low frequency sonar waves to find a prey.
• Hammerheads spend a lot of time well below the sea surface, at depths of more than 250 meters. Hammerhead sharks are creatures of the deep sea and can reach a speed of 25 miles/hr (40 km/hr).
• Their life span is recorded to be of 25 years, if they can successfully manage to evade their natural enemies such as the tiger sharks, killer whales or the great white shark.
• Depending on their type, sex and age, the length of a hammerhead shark can vary from 3 feet to 20 feet.
• The great hammerhead shark is the largest among these and can be as big as 20 feet or 6 meters in length. A matured great hammerhead shark can weigh 450 kg or 1,000 pounds.
• Color of the hammerhead sharks can range from gray-brown to olive-green on top. The color of the belly of the hammerheads is off-white.
• These sharks can be identified by their extended dorsal fin and mallet-shaped head.
• Hammerhead shark habitat includes the warm waters of tropical and temperate seas. Generally, they keep to coastal and offshore waters.
• It is believed that the hammerhead sharks belong to the Carcharhinidae family. Of these the wingedhead shark is considered to be the most basal member of the phylogenetic chart of the hammerhead sharks.
• These carnivore fish sport rows of extremely sharp and triangular teeth.
• Hammerheads like other sharks, do not have mineralized bones in their body. Because of this reason, it is rare to find a fossilized hammerhead shark, a fact which is in sharp contrast to dinosaurs. This has made it very difficult to determine the time of their appearance on Earth.
• A hammerhead shark female gives birth to 12 - 15 pups at a time. The litter size in the Great Hammerhead sharks is 20-40 pups. Hammerhead female, though it is a fish, carries fertilized embryos which gets nutrients via umbilical cords, inside her. Gestation period is of 10-12 months. Young hammerhead shark babies prefer shallow waters off coasts, wherein their enemies cannot penetrate.
• One of the facts which can set your mind at rest is out of the nine hammerheads, only the Great hammerhead, the Smooth hammerhead and the Scalloped hammerhead are aggressive and may attack a swimmer on provocation. If it is an unprovoked incident, their attack on a swimmer or diver may be because of a mistake on their part, in wrongly identifying the swimmer as a seal, their natural prey in the wild.
• In the summer, in schools or herds, they migrate in search of cool waters.

Today, hammerhead shark fishing is for the purpose of supplying their fins which are considered as delicacies. The rest of its body is converted into food for other animals, such as fish or dog. Their teeth are sold as souvenirs to tourists. Most of the time, where there is a ban on fin fishing, to give a slip to the law, fins are cut (easy to store) and the shark, still alive, is thrown in the water. Without its fins shark sinks to the bottom. Out of nine of these species, the Great hammerhead and the Scalloped hammerhead are already in the list of endangered species, while, the Smalleye hammerheads, fished for its vitamin-rich liver and hide, are listed as vulnerable.