Portal:Sharks

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Welcome to the shark portal!

Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii) and are the sister group to the rays. However, the term "shark" has also been (incorrectly) used to refer to extinct members of the subclass Elasmobranchii, which are technically outside the Selachimorpha clade. Notable examples of improper classification include Cladoselache, Xenacanthus, and various other members of the Chondrichthyes class like the holocephalid eugenedontidans.

Under this broader definition, the earliest known sharks date back to more than 420 million years ago. Acanthodians are often referred to as "spiny sharks"; though they are not part of Chondrichthyes proper, they are a paraphyletic assemblage leading to cartilaginous fish as a whole. Since then, sharks have diversified into over 500 species. They range in size from the small dwarf lanternshark (Etmopterus perryi), a deep sea species that is only 17 centimetres (6.7 in) in length, to the whale shark (Rhincodon typus), the largest fish in the world, which reaches approximately 12 metres (40 ft) in length. Sharks are found in all seas and are common to depths up to 2,000 metres (6,600 ft). They generally do not live in freshwater, although there are a few known exceptions, such as the bull shark and the river shark, which can be found in both seawater and freshwater. Sharks have a covering of dermal denticles that protects their skin from damage and parasites in addition to improving their fluid dynamics. They have numerous sets of replaceable teeth.

Several species are apex predators, which are organisms that are at the top of their food chain. Select examples include the tiger shark, blue shark, great white shark, mako shark, thresher shark, and hammerhead shark. (Full article...)

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Dennis Quaid played the lead role of Michael Brody
Jaws 3-D (also known as Jaws 3) is an 1983 horrorthriller film directed by Joe Alves and starring Dennis Quaid (pictured). It is the second sequel to 1975's Jaws.

As SeaWorld, a water park with underwater tunnels and lagoons, prepares for opening, a young great white shark infiltrates the park from the sea, seemingly attacking and killing water skiers and park employees. Once the baby shark is captured, it becomes apparent that it was the mother, a much larger shark who also entered the park, who was the real killer.

The film is notable for making use of 3-D film during the revived interest in the technology in the 1980s, amongst other horror films such as Friday the 13th Part III and Amityville 3-D. Cinema audiences could wear disposable cardboard polarized glasses to create the illusion that elements penetrate the screen. Several shots and sequences were designed to utilise the effect, such as the shark's destruction. Since the 3-D is ineffective in home viewing, the alternative title Jaws III is used for television broadcasts, VHS and DVD.

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Topics


Carcharhiniformes (groundsharks) · Cladoselachiformes (extinct) · Eugeneodontida (extinct) · Heterodontiformes (bullhead sharks) · Hexanchiformes (most primitive sharks) · Hybodontiformes (extinct) · Iniopterygia (extinct) · Lamniformes (mackerel sharks) · Orectolobiformes (carpet sharks and relatives) · Pristiophoriformes (sawsharks and relatives) · Squaliformes (gulper sharks, bramble sharks, lantern sharks, rough sharks, sleeper sharks, dogfish sharks and relatives) · Squatiniformes (angel sharks) · Symmoriida (extinct) · Xenacanthida (also known as Xenacantiformes, extinct)



Shark biology


Shark-human interaction

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