Portal:Sharks

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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 Batoidea (rays and kin). 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 (selachimorphs) 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 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 bull shark, tiger shark, great white shark, mako sharks, thresher sharks, and hammerhead sharks. (Full article...)

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The longfin mako shark, Isurus paucus, is a species of mackerel shark in the family Lamnidae, with a probable worldwide distribution in temperate and tropical waters. An uncommon species, it is commonly lumped together under the name "mako" with its better-known relative, the shortfin mako shark (I. oxyrinchus). The longfin mako is a pelagic species found in moderately deep water, having been reported to a depth of 220 m (720 ft). Growing to a maximum length of 4.3 m (14 ft), the slimmer build and long, broad pectoral fins of this shark suggest that it is a slower and less active swimmer than the shortfin mako.

Longfin mako sharks are predators that feed on small schooling bony fishes and cephalopods. It is uncertain whether this shark is capable of elevating its body temperature above that of the surrounding water like the other members of its family, though it possesses the requisite physiological adaptations. Reproduction in this species is ovoviviparous, meaning that the embryos hatch from eggs inside the uterus. In the latter stages of development, the unborn young are fed non-viable eggs by the mother (oophagy). The litter size is typically two but may be as many as eight. The longfin mako is of limited commercial value as its meat and fins are of lower quality than those of other pelagic sharks; it is caught unintentionally in low numbers across its range. The World Conservation Union has assessed this species as Vulnerable due to its rarity, low reproductive rate, and continuing bycatch mortality.

Did you know (auto-generated)

... that Hixxy and Sharkey created a schism in the UK rave music scene in 1995?
... that since 2018, IKEA's stuffed toy shark Blåhaj has become a popular Internet meme and an icon of the online transgender community?
... that "the Hurricane Shark is real"?
... that the ampullae of Lorenzini enable sharks to sense electric fields?
... that Timo Meier became the first player in San Jose Sharks franchise history to score five goals in one game when he was 25?
... that Alexis Sharkey's last Instagram post before her murder documented her travels to Tulum, Mexico?

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The frilled shark (Chlamydoselachus anguineus) is one of two extant species of shark in the family Chlamydoselachidae, with a wide but patchy distribution in the Atlantic and Pacific Oceans.

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More Did you know? - show different entries

... that the velvet belly lantern shark has proteins in its liver that can detoxify heavy metals such as cadmium, copper, mercury, and zinc?
... that at night, the Pacific angelshark may use bioluminescent plankton to target its prey?
... that the Galapagos shark is often the most abundant shark around oceanic islands?
... that the blotched catshark exhibits fluorescence, with spots that glow yellow under blue light?
... that the grey reef shark is the first shark species known to perform a threat display to warn off divers who are too close?

General images

The following are images from various shark-related articles on Wikipedia.

Image 1Sharksucker (Echeneis naucrates) (from Shark agonistic display)
Image 2Great white shark cages at Isla Guadalupe, Mexico (from Shark cage diving)
Image 3BranchiostomaLanceolatum PioM (from Shark anatomy)
Image 4The gill slits of a whale shark flaring as it expels water from its pharyngeal cavity. (from Shark anatomy)
Image 5White shark cage diving near Gansbaai in South Africa (2015) (from Shark cage diving)
Image 6Postural elements of the agonistic display of the Gray Reef Shark (from Shark agonistic display)
Image 7Shark cage diving (from Shark tourism)
Image 8Depiction of shark anatomy including eggs, pups, and the liver (from Shark anatomy)
Image 9A dissected view of the unique four-chambered heart of the sharkChambers: Sinus Venosus, Atrium, Ventricle, Conus Ateriosus (from Shark anatomy)
Image 10A ventral dissection of a pregnant female dogshark exposing its internal gill slits and internal spiracles. (from Shark anatomy)
Image 11In 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)
Image 12Shark Anatomy (50693674756) (from Shark anatomy)
Image 13Postural configuration of a Gray Reef Shark as it displays agonistic behaviour, in a sculpture (from Shark agonistic display)
Image 14Lateral and cross section view of shark's red and white locomotor muscles (from Shark anatomy)
Image 15Clear agonistic behaviour observed in Great White Shark (from Shark agonistic display)
Image 16Dorsal fin diagram with landmarks labeled. (from Shark anatomy)
Image 17This grey reef shark demonstrates countershading, with its darker dorsal surface and lighter ventral surface. (from Shark anatomy)
Image 18Distribution of highly sensitive ampullae of Lorenzini across the shark's head and rostrum. (from Shark agonistic display)
Image 19Great 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)
Image 20Placoid Scale (from Shark anatomy)
Image 21A 14-foot (4.3 m), 1,200-pound (540 kg) tiger shark caught in Kāne'ohe Bay, Oahu, in 1966
Image 22Sharks swimming outside shark-proof cage with people inside (from Shark cage diving)
Image 23A sign at Pyramid Rock Beach in Hawaii warning about a shark sighting, 2015 (from Shark tourism)
Image 24The major features of sharks (from Shark anatomy)
Image 25Anti-cull protesters on Perth's Cottesloe Beach in Western Australia in 2014 (from Shark culling)
Image 26The whale shark, the world's largest fish, is classified as Endangered.

Binding legislation and harvest management strategies... are urgently needed to address the disproportionate impact of fisheries on cartilaginous fishes.

– IUCN global study 2010

(from List of threatened sharks)

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Topics

Shark · Outline of sharks

Shark orders

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)

Major species