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...)

Selected article -

The silvertip shark, Carcharhinus albimarginatus, is a large species of requiem shark found in the tropical Indian and Pacific Oceans. This species is often encountered around offshore islands and coral reefs, and has been known to dive to a depth of 800 m (2,600 ft). The silvertip shark resembles a larger, bulkier grey reef shark (C. amblyrhynchos), and can be easily identified by the prominent white margins on its fins. It attains a maximum length of 3 m (10 ft).

An aggressive, powerful apex predator, the silvertip shark feeds on a wide variety of bony fishes, as well as eagle rays, smaller sharks, and cephalopods. This species dominates other requiem sharks of equal size when competing for food, and larger individuals are often heavily scarred from conflicts with others of its species. As with other members of its family, the silvertip shark is viviparous, with females giving birth to 1–11 pups in the summer. Silvertip sharks are regarded as potentially dangerous to humans, as they often approach divers quite closely. This species is taken by commercial fisheries for its meat and fins, though there is currently insufficient data for the World Conservation Union to assess its conservation status.

Did you know (auto-generated)

... that the parasitic copepod Driocephalus cerebrinoxius burrows into the brains of sharks through their noses?
... that shark fin is one of the "four sea delicacies", a quartet of luxury seafoods in Chinese cuisine?
... 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, during Real Madrid's 1927 tour of the Americas, José María Muñagorri nearly jumped into shark-infested waters to rescue a teammate?
... that a shark cost a competitor a silver medal in the spearfishing event at the 2014 Micronesian Games?

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 lemon shark is a shark belonging to the family Carcharhinidae that can grow 10 feet (3.0 m) long. It is a popular choice for study, as it survives well in captivity.

More Did you know? -

... that the whitetip reef shark may have contributed to the Hawaiian myth of ʻaumākua, family guardian spirits, due to the "loyalty" of sharks that stay in the same area for years?
... that individual smalltooth sand tigers have been documented returning to the same location off Lebanon every summer?
...that Mustelus hacat is a species of smooth-hound shark discovered in 2003 in the Sea of Cortez, off the coast of Mexico?
... that during the summer the finetooth shark is found exclusively in water less than 10 m (30 ft) deep?
... that the Canary Islands are one of the few places left where there are still substantial numbers of angelsharks, once common all around Europe?
...that whilst most sharks are poikilothermic, species in the family Lamnidae are homeothermic?

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

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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