Portal:Sharks
Welcome to the shark portal
Sharks are a group of elasmobranch cartilaginous fishes characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the division Selachii and are the sister group to the Batomorphi (rays and skates). Some sources extend the term "shark" as an informal category including extinct members of Chondrichthyes (cartilaginous fish) with a shark-like morphology, such as hybodonts. Shark-like chondrichthyans such as Cladoselache and Doliodus first appeared in the Devonian Period (419–359 million years), though some fossilized chondrichthyan-like scales are as old as the Late Ordovician (458–444 million years ago). The earliest confirmed modern sharks (Selachii) are known from the Early Jurassic around 200 million years ago, with the oldest known member being Agaleus, though records of true sharks may extend back as far as the Permian.
Sharks 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. They 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 sharks, which can be found in both seawater and freshwater, and the Ganges shark, which lives only in freshwater. Sharks have a covering of placoid scales (denticles) that protects the skin from damage and parasites in addition to improving their fluid dynamics. They have numerous sets of replaceable teeth.
Several shark species are apex predators, which are organisms that are at the top of their food chain with select examples including the bull shark, tiger shark, great white shark, mako sharks, thresher sharks and hammerhead sharks. Some sharks are filter-feeding planktivores, such as the whale shark and basking shark, which are among the largest fish ever lived. (Full article...)
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Jaws is regarded as a watershed film in motion picture history, the father of the summer blockbuster movie and one of the first "high concept" films.[1][2] Due to the film's success in advance screenings, studio executives decided to distribute it in a much wider release than ever before. The Omen followed suit in the summer of 1976 and then Star Wars one year later in 1977, cementing the notion for movie studios to distribute their big-release action and adventure pictures (commonly referred to as tentpole pictures) during the summer. The film was followed by three sequels, none with the participation of Spielberg or Benchley: Jaws 2 (1978), Jaws 3-D (1983) and Jaws: The Revenge (1987). A video game titled Jaws Unleashed was produced in 2006. Despite the high levels of violence in the film due to the graphic depiction of the shark's attacks, it was only rated PG.
Did you know (auto-generated)
- ... that the parasitic copepod Driocephalus cerebrinoxius burrows into the brains of sharks through their noses?
- ... that a shark cost a competitor a silver medal in the spearfishing event at the 2014 Micronesian Games?
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More Did you know? -
- ... that male Arabian carpetsharks competing for a mate have been known to bite the claspers of their rivals?
- ... that the porbeagle has been known to "play" with kelp fronds, pieces of wood, and fishing floats?
- ... that the blind shark and the bluegrey carpetshark close their eyes when taken out of the water?
- ... that male Arabian carpetsharks competing for a mate have been known to bite the claspers of their rivals?
- ... that the whitefin, Cook's, Australian reticulate, spotted, leopard-spotted, painted, flagtail, speckled, saddled, and narrowbar swellsharks were all scientifically described in 2008, more than doubling the number of species in the genus Cephaloscyllium?
General images
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In a milestone decision in 2013, CITES prohibited international trade in the fins of the scalloped hammerhead (pictured) and four other shark species. (from List of threatened sharks) -
Distribution of highly sensitive ampullae of Lorenzini across the shark's head and rostrum. (from Shark agonistic display) -
Postural elements of the agonistic display of the Gray Reef Shark (from Shark agonistic display) -
Shark cage diving (from Shark tourism) -
Anti-cull protesters on Perth's Cottesloe Beach in Western Australia in 2014 (from Shark culling) -
The major features of sharks (from Shark anatomy) -
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Lateral and cross section view of shark's red and white locomotor muscles (from Shark anatomy) -
This grey reef shark demonstrates countershading, with its darker dorsal surface and lighter ventral surface. (from Shark anatomy) -
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The gill slits of a whale shark flaring as it expels water from its pharyngeal cavity. (from Shark anatomy) -
Clear agonistic behaviour observed in Great White Shark (from Shark agonistic display) -
Depiction of shark anatomy including eggs, pups, and the liver (from Shark anatomy) -
Postural configuration of a Gray Reef Shark as it displays agonistic behaviour, in a sculpture (from Shark agonistic display) -
Great white shark cages at Isla Guadalupe, Mexico (from Shark cage diving) -
A sign at Pyramid Rock Beach in Hawaii warning about a shark sighting, 2015 (from Shark tourism) -
Sharks swimming outside shark-proof cage with people inside (from Shark cage diving)
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A dissected view of the unique four-chambered heart of the sharkChambers: Sinus Venosus, Atrium, Ventricle, Conus Ateriosus (from Shark anatomy) -
Placoid Scale (from Shark anatomy) -
A ventral dissection of a pregnant female dogshark exposing its internal gill slits and internal spiracles. (from Shark anatomy) -
Shark Anatomy (50693674756) (from Shark anatomy) -
Dorsal fin diagram with landmarks labeled. (from Shark anatomy) -
Great white shark at Isla Guadalupe, Mexico, August 2006. Animal estimated at 11–12 feet (3.3 to 3.6 m) in length, age unknown. (from Shark tourism) -
Sharksucker (Echeneis naucrates) (from Shark agonistic display) -
The whale shark, the world's largest fish, is classified as Endangered.(from List of threatened sharks)Binding legislation and harvest management strategies... are urgently needed to address the disproportionate impact of fisheries on cartilaginous fishes.
– IUCN global study 2010 -
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Sources
- ^ "Rise of the blockbuster". BBC News Online. Retrieved 2006-08-20.
- ^ Wyatt, Justin. (1994) High Concept: Movies and Marketing in Hollywood. Austin: University of Texas Press. ISBN 0-292-79091-0
