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) to 18.8 metres (62 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 that ever lived. (Full article...)

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The smalltooth sand tiger or bumpytail ragged-tooth, Odontaspis ferox, is a species of sand shark, family Odontaspididae, with a patchy but worldwide distribution in tropical and warm temperate waters. They usually inhabit deepwater rocky habitats, though they are occasionally encountered in shallow water, and have been known to return to the same location year after year. This rare species is often mistaken for the much more common grey nurse shark (Carcharias taurus), from which it can be distinguished by its first dorsal fin, which is larger than the second and placed further forward. It grows to at least 4.1 m (13.5 ft) in length.

Very little is known of the biology and behavior of the smalltooth sand tiger. It is an active predator of benthic bony fishes, invertebrates, and cartilaginous fishes. This species is thought to be ovoviviparous with oophagous embryos like other mackerel sharks. In contrast to its formidable size and appearance, this shark is harmless, having never been known to behave aggressively towards humans. There is concern that its numbers are declining due to human activities in the Mediterranean and elsewhere, though existing data is inadequate for a full assessment of its conservation status.

Did you know (auto-generated)

... that Japanese businessman Yasuyoshi Kato used embezzled funds to support his wife, who bought twenty Arabian horses, several emus, llamas, potbellied pigs, miniature cattle, and nurse sharks?
... 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?
... that, during Real Madrid's 1927 tour of the Americas, José María Muñagorri nearly jumped into shark-infested waters to rescue a teammate?
... that shark fin is one of the "four sea delicacies", a quartet of luxury seafoods in Chinese cuisine?

Related portals

WikiProjects

WikiProjects related to sharks:

Selected picture -

The jaw of a shortfin mako shark. The species feeds mainly upon cephalopods, bony fishes including mackerel, tuna, bonito, and swordfish, but it may also eat other sharks, porpoises, sea turtles, and seabirds.

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

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

Image 1The 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)
Image 2Postural configuration of a Gray Reef Shark as it displays agonistic behaviour, in a sculpture (from Shark agonistic display)
Image 3White shark cage diving near Gansbaai in South Africa (2015) (from Shark cage diving)
Image 4Shark cage diving (from Shark tourism)
Image 5Sharks swimming outside shark-proof cage with people inside (from Shark cage diving)
Image 6Shark Anatomy (50693674756) (from Shark anatomy)
Image 7Sharksucker (Echeneis naucrates) (from Shark agonistic display)
Image 8A ventral dissection of a pregnant female dogshark exposing its internal gill slits and internal spiracles. (from Shark anatomy)
Image 9Postural elements of the agonistic display of the Gray Reef Shark (from Shark agonistic display)
Image 10Great 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 11Placoid Scale (from Shark anatomy)
Image 12This grey reef shark demonstrates countershading, with its darker dorsal surface and lighter ventral surface. (from Shark anatomy)
Image 13A dissected view of the unique four-chambered heart of the sharkChambers: Sinus Venosus, Atrium, Ventricle, Conus Ateriosus (from Shark anatomy)
Image 14Anti-cull protesters on Perth's Cottesloe Beach in Western Australia in 2014 (from Shark culling)
Image 15Lateral and cross section view of shark's red and white locomotor muscles (from Shark anatomy)
Image 16The major features of sharks (from Shark anatomy)
Image 17Depiction of shark anatomy including eggs, pups, and the liver (from Shark anatomy)
Image 18The gill slits of a whale shark flaring as it expels water from its pharyngeal cavity. (from Shark anatomy)
Image 19A sign at Pyramid Rock Beach in Hawaii warning about a shark sighting, 2015 (from Shark tourism)
Image 20A 14-foot (4.3 m), 1,200-pound (540 kg) tiger shark caught in Kāne'ohe Bay, Oahu, in 1966
Image 21Clear agonistic behaviour observed in Great White Shark (from Shark agonistic display)
Image 22Branchiostoma lanceolatum (from Shark anatomy)
Image 23Dorsal fin diagram with landmarks labeled. (from Shark anatomy)
Image 24Distribution of highly sensitive ampullae of Lorenzini across the shark's head and rostrum. (from Shark agonistic display)
Image 25Great white shark cages at Isla Guadalupe, Mexico (from Shark cage diving)
Image 26In this drawing, there is a diagram of the placement of shark organs. From this model, we can see and distinguish the placement of organs compared with other species. EX. The testes of a shark are located on the ventral plane, near the fins, while a human's testes are located further down, near the bladder. (from Shark anatomy)
Image 27In 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)

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