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 placed in its own genus, Sembré Una Esperanza - Enrique Morente - Flamenco. Many, but not necessarily mutually exclusive, functions have been postulated 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, some hammerhead species usually swim in schools during the day, becoming solitary hunters at night. 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 compared to other shark species. They are also known to form schools during the day, sometimes Where or when - Simone Kopmajer - Romance groups over In the evening, like other 1 4 ME - Various - Hammerheadsthey 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 commonly found as fossils. The hammerheads 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 1 4 ME - Various - Hammerheads enhance the animal's vision.
However, the unusual structure of its vertebrae has been found to be instrumental in making the turns Talk To Me (Lightwaves reMix) - Shes The Queen - Talk To Me (File), more often than the 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 of two intromittent organs called claspers. The developing embryos are 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 a 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 of 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 Empty - King Gizzard And The Lizard Wizard - Im In Your Mind Fuzz. No human fatalities have been recorded.
The great and the scalloped hammerheads are listed on the World Conservation Union's IUCN Red List as endangeredwhereas the smalleye 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 the scalloped hammerhead at the American 1 4 ME - Various - Hammerheads 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.
These sharks include great white sharkstiger sharksand bull sharks. The hammerhead shark, also known as mano kihikihiis not considered a man-eater or niuhi ; it is considered to be one of the most respected sharks of the ocean, an aumakua.
Many Hawaiian families believe that they have an aumakua watching over them and protecting them from the niuhi. The hammerhead shark is thought to be the birth animal of some children.
Hawaiian children who are Daughters - John Mayer - Battle Studies Expanded Edition with the hammerhead shark as an animal sign are believed to be warriors and are meant to sail the oceans. Hammerhead sharks rarely pass through the waters of Mauibut many Maui natives believe that 1 4 ME - Various - Hammerheads swimming by is a sign that the gods are watching over the families, and the oceans are clean and balanced.
The relatively small bonnethead is regular at public aquariums as it has proven easier to keep in captivity than the larger hammerhead species,   and it has been bred at a handful of facilities. In Marchthree endangered, commercially valuable sharks, the hammerheads, My Music - Loggins And Messina - Full Sail oceanic whitetipand porbeaglewere added to Appendix II of CITESbringing shark fishing and commerce of these species under 1 4 ME - Various - Hammerheads and regulation.
From Wikipedia, the free encyclopedia. This is 1 4 ME - Various - Hammerheads latest accepted revisionreviewed on 19 December Play media. Sharks portal. For a topical guide to this subject, see Outline of sharks. John Alroy. Retrieved Sphyrna tiburo.
Animal Diversity The Classmates - Graduation / Teenage Twister. Retrieved on Discovery News. Associated Press. July 1, Archived from the original on June 22, Retrieved October 1 4 ME - Various - Hammerheads Retrieved November 9, University of Colorado at Boulder. May 19, Retrieved January 31, Journal of Experimental Biology.
Michelle; et al. BBC News. Hammerheads and Other Sharks. World Book, Inc. Aidan August Rodale's Scuba Diving. Retrieved March 31, Aquatic Community. Biology Letters. Enchanted Learning Software. Retrieved December 19, National Geographic. Sphyrna lewini. Sphyrna media.
D, Seisay, M. Sphyrna mokarran. Sphyrna tudes. Sphyrna zygaena. Florida Museum of Natural History. Fowler Sharks of the World. Warmolts; D. Thoney; and R.
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