Natural History of the Great White Shark
The Natural History of the Great White Shark (GREAT) WHITE SHARK: Kingdom- Animalia, Phylum- Vertebrata, Class- Chondrichthyes, Order – Lamniformes, Family – Lamnidae, Genus – Carcharodon, Species – carcharias [Martins & Knickle 2010] The great white shark, Carcharodon carcharias, which is also known as the white shark and white pointer, has, been one of the most feared creatures on earth, they are viewed as killing machines that will stop at nothing, this stereotype of Carcharodon carcharias is greatly influenced by the movie Jaws.
While this is a common perception of white sharks, some daring explorers have not only free-dived with these feared creatures; they lived to talk about it. Not that diving with great white sharks is something that most people dream of doing nor is it recommended, but these bold experiments have shown that these fascinating, however intimidating, creatures are not predators of man. [Parker 1999] The great white shark, Carcharodon carcharias, is the largest known predatory fish in the sea. They reach lengths of over 21 feet long and weigh up to 2,268 kg.
They have a pointed snout, pitch black eyes, a heavy, torpedo-shaped body, and a curved, nearly equal-lobed tail fin that is supported on each side by a keel. The great white swims in a stiff-bodied, tuna-like fashion, unlike the twisting whole-bodied swimming stroke of most sharks. The name “white shark” is thought to have come from its common all-white belly. The dorsal coloring of great white sharks, ranges from pale to dark gray and can vary extremely depending on lighting, water color and visibility. [Martins & Knickle 2010] The great white’s average length is around 9 feet, but there have been reports of sharks as large as 26 feet.
The great white belongs to the Family Lamnidae, which includes Mako and Salmon Sharks. Along the California coastline, adult great whites are an important predator of marine mammals, particularly the fatty calorie-rich elephant seals. Young Great White’s feed mostly on fish and add marine mammals to their diet when they are large enough in size and weight. [Fergusson 2009] White sharks are able to prey on such large creatures with their large upper teeth, which are triangular in shape and serrated to cut large pieces of flesh from prey.
The bottom teeth are narrower and used to hold prey. An unusual characteristic that the white shark possesses, shared by other Mackerel Sharks and Thresher Sharks, is the ability to maintain parts of their body, swimming muscles, stomach, and brain, at temperatures above that of the surrounding water, which classifies them as endothermic or warm-blooded. [Martins & Knickle 2010] Great white sharks, Carcharodon carcharias, have one of the widest geographic ranges of any marine animal, they are found in all cold temperate and tropical waters.
They were long thought to be primarily coastal residents; however, from recent satellite tracking studies we now know that they migrate long distances, sometimes crossing entire ocean basins. Along the central California coast, they can be found hunting near areas where seals are prevalent, this occurs from the months of October through March. They can also be found in the western cape of South Africa, they are found near areas where cape fur seals are common, from the months of May to September. In North American waters, white sharks have been reported from Newfoundland to Florida and from the Aleutian Islands to southern Mexico.
Even though Great White’s are very common in their widespread range, however, they are becoming increasingly rare, this is thought to be due to their reproduction and mating habits. [Martins ; Knickle 2010] Very little is known about the reproductive cycle of the great white shark. Development is ovoviviparous. The smallest known free swimming white shark measured 3 feet and weighed about 35 pounds. Along the west coast of North America, it is believed that great whites give birth to their live young in the warmer southern California waters.
The young may then slowly migrate northward as they grow larger. Ovoviviparous means that the eggs are retained within the body of the female in a brood chamber where the embryo develops, receiving nourishment from a yolk sac. This is the method of reproduction for the “live-bearing” fishes where pups hatch from egg capsules inside the mother’s uterus and are born soon afterward. [Martin & Knickle 2010] The Gestation period of Great White Sharks is unknown, but may be longer than a year, after which mother great whites may take a year “off” before becoming pregnant again.
Litter size ranges from 2 to 10 pups, each 3-3. 5 feet long at birth. Male great whites mature at 9. 5-10 feet in length and 9 to 10 years of age; females mature at 12 feet at 14 to 16 years. Maximum lifespan is believed to be more than 30 years. [Canadian Shark Research Laboratory 2010] Recent research on interactions between great whites and various species of seals and sea lions suggests that great whites hunt their prey visually. Using their dark dorsal colors to help them blend in while cruising near rocky bottoms, they watch for unsuspecting seals that are resting on the surface above.
When an animal is in their sight, Great White’s accelerate quickly to the surface and ram into their prey, simultaneously stunning it and taking a large bite. They then return to feed on the remains. [Parker 1999] It should be noted that great whites often receive extensive injuries from their prey, many have been observed with scarring on the head from the teeth and claws of elephant seals and sea lions. [Martins ; Knickle 2010] It is still uncertain whether great whites are territorial; however, current observations point to that they seem to possess a home range.
Recent research has shown that great whites exhibit complex social behavior that institutes rank among individuals. After one great white makes a kill, sometimes others come and feed off the same kill with no apparent aggressive interactions. [ARKive 2009] Although great whites, Carcharodon carcharias, have little commercial value, fishing for these sharks became a popular sport with big game fish anglers. The fearsome reputation of the great white has given it almost legendary status as an apex predator and they are often killed by humans for sport and for their jaws, teeth and fins.
Shark fins are especially valued in Asian countries; shark fin soup is a delicacy. [Ling 2009] Great whites are very curious and most so-called “attacks” appear to be motivated by curiosity rather than a desire to feed and most attacks on humans are not fatal. [Martin 2010] Ironically, the great white is far more threatened by humans than we are of them. [Ling 2009] Great white sharks, Carcharodon carcharias, are now listed as Vunerable on the IUCN Red List of Threatened Species due to: “Despite the high profile media attention the Great White Shark (Carcharodon carcharias) receives, relatively little is known about its biology.
It appears to be fairly uncommon compared to other widely distributed species, being most frequently reported from South Africa, Australia, California and the northeast United States. World catches of Great White Sharks from all causes are difficult to estimate, though it is known to have a relatively low intrinsic rebound potential. Threats to the species include targeted commercial and sports fisheries for jaws, fins, game records and for aquarium display; protective beach meshing; media-fanned campaigns to kill Great White Sharks after a biting incident ccurs; and degradation of inshore habitats used as pupping and nursery grounds. “[Fergusson 2009] Due to the importance of the Great White as a key predator in marine ecosystems, the great white was granted protected status in 1991 in South Africa and in 1994 in California and Australia and is listed on CITES Appendix II. Great white sharks are also an important species for marine eco-tourism, observed by divers from the safety of cages in South Africa, southern Australia and Mexico. [Martins ; Knickle 2010] Great White Sharks are mysterious, graceful, complex creatures.
Because so little is known about how they mate and reproduce it is our responsibility to try and educate others about the threat to the Great White population that is rapidly increasing every day. With our help we could perhaps prevent the worst possible result, having Great Whites put on the endangered species list. Works Cited: 1. ) Martins, Carol ; Knickle, Craig. Florida Museum of Natural History. 2010. http://www. flmnh. ufl. edu/fish/Gallery/Descript/Whiteshark/whiteshark. html 2. ) Parker, Steve and Jane.
The Encyclopedia of Sharks. Quintet Publishing Limited. Canada, 1999. 3. ) Perrine, Doug. Sharks. World Life Library. Voyager Press. Singapore, 1995. 4. ) Fergusson, I. , Compagno, L. J. V. ; Marks, M. 2005. Carcharodon carcharias. In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009. 2. ;www. iucnredlist. org;. 5. ) Ling, Lisa. Planet in Peril-Shark fin soup alters an ecosystem. CNN. 2009. http://www. cnn. com/2008/WORLD/asiapcf/12/10/pip. shark. finning/index. html. 6. ) ARKive Images of Life on Earth.
Great White Shark (Carcharodon carcharias). 2009. http://www. arkive. org/great-white-shark/carcharodon-carcharias/info. html. 7. ) Canadian Shark Research Laboratory. White Sharks. 2010. http://www. marinebiodiversity. ca/shark/english/white. htm. 8. ) Martin, Glen. Beyond Jaws. Academic Search Premiere. Bay Nature; Jan-Mar2010, Vol. 10 Issue 1, p16-23, 5p. http://library. depaul. edu. ezproxy1. lib. depaul. edu/CheckURL. aspx? address=http://search. ebscohost. com. ezproxy1. lib. depaul. edu/login. aspx? direct=true;