Portal:Sharks

Sharks are a group of elasmobranch cartilaginous fish 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...)

The Pacific angelshark, Squatina californica, is a species of angel shark, family Squatinidae, found in the eastern Pacific Ocean from Alaska to the Gulf of California, and from Ecuador to Chile, although those in the Gulf of California and southeastern Pacific may in fact be separate species. The Pacific angelshark inhabits shallow, coastal waters on sandy flats, usually near rocky reefs, kelp forests, or other underwater features. This species resembles other angel sharks in appearance, with a flattened body and greatly enlarged pectoral and pelvic fins. Characteristic features of this shark include a pair of cone-shaped barbels on its snout, angular pectoral fins, and a brown or gray dorsal coloration with many small dark markings. It attains a maximum length of 1.5 m (4.9 ft).

An ambush predator, Pacific angelsharks conceal themselves on the sea floor and wait for approaching prey, primarily bony fishes and squid. Prey are targeted visually and, with a quick upward thrust of the head, snatched in protrusible jaws. Individual sharks actively choose ideal ambush sites, where they remain for several days before moving on to a new one. This species is more active at night than during the day, when it stays buried in sediment and seldom moves. Reproduction is ovoviviparous, meaning that the embryos hatch inside the mother's uterus and are sustained by a yolk sac until birth. Females give birth to an average of six young every spring.

Pacific angelsharks are not dangerous to humans unless provoked, in which case their bite can cause a painful injury. They are valued for their meat and are captured by commercial and recreational fishers across their range. A targeted gillnet fishery for this species began off Santa Barbara, California in 1976 and ended in 1994, after overfishing and new regulations led to its near-collapse. This species is now mainly fished in Mexican waters. The World Conservation Union has assessed this species as Near Threatened, as the Californian population is largely protected and recovering, while the impact of Mexican fisheries is unknown.

... that Hixxy and Sharkey created a schism in the UK rave music scene in 1995?
... that a shark cost a competitor a silver medal in the spearfishing event at the 2014 Micronesian Games?
... that the parasitic copepod Driocephalus cerebrinoxius burrows into the brains of sharks through their noses?
... that Timo Meier became the first player in San Jose Sharks franchise history to score five goals in one game when he was 25?

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Sharks

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WikiProjects related to sharks:

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

The leopard shark is a species of houndshark found along the Pacific coast of North America from the U.S. state of Oregon to Mazatlán in Mexico.

... 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?

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

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

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)

For additional lists of marine life-related featured articles and good articles see:

WikiProject Cetaceans § Featured and Good Content
Portal:Fish/Recognized content
Portal:Marine life/Recognized content

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