Sphyrna mokarranGreat Hammerhead
Geographic Range
Great hammerhead sharks occur in all tropical waters worldwide.
- Biogeographic Regions
- oceanic islands
- indian ocean
- atlantic ocean
- pacific ocean
Habitat
These sharks are found in both open ocean and shallow coastal waters. During summer they may make small migrations towards more northerly areas.
Physical Description
Great hammerhead sharks posses a virtually straight anterior margin of the head with a deep central indentation. They have high second dorsal fins and the pelvic fins have curved rear margins. The teeth are triangular with extraordinarily serrated edges, becoming increasingly oblique toward the corners of the mouth. Their coloration varies from deep olive green to brownish grey above and white below. They are generally 4 to 6 m in length.
- Other Physical Features
- bilateral symmetry
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- Range mass
- 400 to 460 kg
- 881.06 to 1013.22 lb
Reproduction
Great Hammerhead sharks are viviparous. At a length of 3m, maturity is reached. Litters are made up of between 20 and 40 pups. Young are born in the summer season and are approximately 70 cm in length. Head shape of a newborn pup is more rounded than that of an adult but this changes as they grow.
Behavior
Little is known about behavior or social systems of great hammerhead sharks. Unlike scalloped hammerhead sharks, they are solitary hunters and dangerous to humans.
- Key Behaviors
- natatorial
- motile
Food Habits
Great hammerhead sharks feed on rays, smaller sharks, and many species of bony fishes.
Economic Importance for Humans: Positive
Great hammerhead sharks are classified as game fish, as are all large hammerhead sharks. Their skin is often used for leather.
Economic Importance for Humans: Negative
These sharks are potentially dangerous to humans and cases of attacks by great hammerhead sharks have been documented.
Conservation Status
Great hammerhead shark populations seem to be stable.
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- IUCN Red List
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Endangered
More information
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- IUCN Red List
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Endangered
More information
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- US Federal List
- No special status
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- CITES
- No special status
Contributors
Robin Street (author), University of Michigan-Ann Arbor.
Glossary
- Atlantic Ocean
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the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
- Pacific Ocean
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body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
- bilateral symmetry
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having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- coastal
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the nearshore aquatic habitats near a coast, or shoreline.
- motile
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having the capacity to move from one place to another.
- natatorial
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specialized for swimming
- native range
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the area in which the animal is naturally found, the region in which it is endemic.
- oceanic islands
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islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.
- reef
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structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.
References
The Sharks of North american Waters; Castro, HoseI.;Texas A&M University Press, 1983.
Sharks;Stevens, John D.; Merehurst Press,1987.