The hammerhead sharks are a group of sharks in the family Sphyrnidaeso named for the unusual and distinctive structure of their heads, which are flattened and laterally extended into a "hammer" shape called a cephalofoil. Most hammerhead species are placed in the genus Sphyrnawhile the winghead shark is Asexual reproduction hammerhead sharks in its own genus, Eusphyra.
Many, but not necessarily mutually exclusive, functions have been proposed for the cephalofoil, including sensory reception, manoeuvering, and prey manipulation. Hammerheads are found worldwide in warmer waters along coastlines and continental shelves. Unlike most sharks, hammerheads usually swim in schools during the day, becoming solitary hunters at night. Large schools are also seen in the waters off southern and eastern Africa.
The known species range from 0. Their bellies are white, which allows them to blend into the ocean when viewed from the bottom and sneak up on their prey. Hammerheads have disproportionately small mouths. They are also known to form schools during the day, sometimes in groups over In the evening, like other sharks, they become solitary hunters.
National Geographic explains that hammerheads can be found in warm tropical waters, but during the summer, they participate in a mass migration to search for cooler waters. Since sharks do not have mineralized bones and rarely fossilizetheir teeth alone are
Asexual reproduction hammerhead sharks found as fossils.
The seem closely related to the carcharhinid sharks that evolved during the mid- Tertiary period. According to DNA studies, the ancestor of the hammerheads probably lived in the Miocene epoch about 20 million years ago. Using mitochondrial DNAa phylogenetic tree of the hammerhead sharks showed the winghead shark as its most basal member.
As the winghead shark has proportionately the largest "hammer" of the hammerhead sharks, this suggests that the first ancestral hammerhead sharks also had large hammers.
A theory has been advanced that the hammer-like shape of the head may have evolved at least in part to enhance the animal's vision. However, the unusual structure of its vertebrae has been found to be instrumental in making the turns correctly, more often than Asexual reproduction hammerhead sharks shape of its head, though it would also shift and provide lift. From what is known about the winghead shark, the shape of the hammerhead apparently has to do with an evolved sensory function.
Like all sharks, hammerheads have electroreceptory sensory pores called ampullae of Lorenzini. The pores on the shark's head lead to sensory tubes, which detect electricity given off by other living creatures. Reproduction occurs only once a year for hammerhead sharks, and usually occurs with the male shark biting the female shark violently until she agrees to mate with him.
Like other sharks, fertilization is internal, with the male transferring sperm to the female through one
Asexual reproduction hammerhead sharks two intromittent organs called claspers. The developing embryos at first sustained by a yolk sac.
When the supply of yolk is exhausted, the depleted yolk sac transforms into a structure analogous to a mammalian placenta called a "yolk sac placenta" or "pseudoplacenta"through which the mother delivers sustenance until birth. Once the baby sharks are born, they are not taken care of by the parents in any way.
Usually, a litter consists of 12 to 15 pups, except for the great hammerhead, which gives birth to litters of 20 to 40 pups. These baby sharks huddle together and swim toward warmer water until they are old enough and large enough to survive on their own.
Inthe bonnethead shark was found to be capable of asexual reproduction via automictic parthenogenesisin which "Asexual reproduction hammerhead sharks" female's ovum fuses with a polar body to form a zygote without the need for a male.
This was the first shark known to do this. Hammerhead sharks are known to eat a large range Asexual reproduction hammerhead sharks prey such as fish including other sharkssquidoctopusand crustaceans. Stingrays are a particular favorite. These sharks are often found swimming along the bottom of the ocean, stalking their prey. Their unique heads are used as a weapon when hunting down prey.
The hammerhead shark uses its head to pin down stingrays and eats the ray when the ray is weak and in shock. They may swallow it unintentionally, but they are able to partially digest it. This is the only known case of a potentially omnivorous species of shark.
According to the International Shark Attack Filehumans have been subject to 17 documented, unprovoked attacks by hammerhead sharks within the genus Sphyrna since AD. No human fatalities have been recorded. "Asexual reproduction hammerhead sharks" great and the scalloped hammerheads are listed on the World Conservation Union's IUCN Red List as endangeredwhereas the
Asexual reproduction hammerhead sharks hammerhead is listed as vulnerable.
The status given to these sharks is as a result of overfishing and demand for their fins, an expensive delicacy. Among others, scientists expressed their concern about the plight of Asexual reproduction hammerhead sharks scalloped hammerhead at the American Association for the Advancement of Science annual meeting in Boston.
The young swim mostly in shallow waters along shores all over the world to avoid predators. Shark fins are prized as a delicacy in certain countries in Asia such as Chinaand overfishing is putting many hammerhead sharks at risk of extinction. Fishermen who harvest the animals typically cut off the fins and toss the remainder of the fish, which is often still alive, back into the sea.
In native Hawaiian culture, sharks are considered to be gods of the sea, protectors of humans, and cleaners of excessive ocean life. Some of these sharks are believed to be family members who died and have been reincarnated into shark form. However, some sharks are considered man-eaters, also known as niuhi.