Portal:Sharks

Welcome to the shark portal

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 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 oldest modern sharks (selachimorphs) are known from the Early Jurassic, about 200 million years ago.

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 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...)

Selected article -

A captive great hammerhead at the Georgia Aquarium

The great hammerhead, Sphyrna mokarran, is the largest of the hammerhead sharks (family Sphyrnidae), attaining a maximum length of 6.1 m (20 ft). It is found in tropical and warm temperate waters worldwide, inhabiting coastal areas and the continental shelf. The great hammerhead can be distinguished from other hammerheads by the shape of its "hammer" (called the "cephalofoil"), which is wide with an almost straight front margin, and by its tall, sickle-shaped first dorsal fin. A solitary, strong-swimming apex predator, the great hammerhead feeds on a wide variety of prey ranging from crustaceans and cephalopods, to bony fishes, to smaller sharks. Observations of this species in the wild suggest that the cephalofoil functions to immobilize stingrays, a favored prey. This species has a viviparous mode of reproduction, bearing litters of up to 55 pups every two years.

Although potentially dangerous, the great hammerhead rarely attacks humans. It sometimes behaves inquisitively toward divers and should be treated with respect. This shark is heavily fished for its large fins, which are extremely valuable on the Asian market as the main ingredient of shark fin soup. As a result, great hammerhead populations are declining substantially worldwide, and it has been assessed as Endangered by the World Conservation Union.

Did you know (auto-generated)

... that Hixxy and Sharkey created a schism in the UK rave music scene in 1995?
... that Alexis Sharkey's last Instagram post before her murder documented her travels to Tulum, Mexico?
... 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 ampullae of Lorenzini enable sharks to sense electric fields?
... that "the Hurricane Shark is real"?
... that Timo Meier became the first player in San Jose Sharks franchise history to score five goals in one game when he was 25?

Related portals

WikiProjects

WikiProjects related to sharks:

WikiProject Science
- WikiProject Biology
  - WikiProject Tree of Life
    - WikiProject Animals
      - WikiProject Fishes
        WikiProject Sharks
WikiProject Aquarium Fishes
WikiProject Fishing

Selected picture -

The great white shark is an exceptionally large lamniform shark found in coastal surface waters in all major oceans.

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

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

Basking shark · Blue shark · Bull shark · Great hammerhead · Great white shark · Grey reef shark · Hammerhead shark · Megalodon · Megamouth shark · Nurse shark · Oceanic whitetip shark · Requiem shark · Scalloped hammerhead · Shortfin mako shark · Swellshark · Thresher shark · Tiger shark · Whale shark

Shark biology

Ampullae of Lorenzini · Mermaid's purses · Physical characteristics of sharks · Shark teeth · Shark threat display

Shark-human interaction

Attack (drum lines, International Shark Attack File, Jersey Shore shark attacks of 1916, list of fatal, unprovoked shark attacks in the United States, shark net, shark proof cage, shark suit, Summer of the Shark) · Captivity (shark tunnel) · Conservation (grey nurse shark conservation, Shark Alliance, Shark Conservation Act, Shark Trust) · Fishing (International Land-Based Shark Fishing Association, land-based shark fishing) · Products (shark cartilage, shark finning, shark fin soup, shark liver oil)

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