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 -

Captive sicklefin lemon shark at Sidney Aquarium

The sicklefin lemon shark or sharptooth lemon shark, Negaprion acutidens, is a species of requiem shark, family Carcharhinidae, widely distributed in the tropical waters of the Indo-Pacific. It is closely related to the better-known lemon shark (N. brevirostris) of the Americas; the two species are almost identical in appearance, both being stout-bodied sharks with broad heads, two dorsal fins of nearly equal size, and a plain yellow-tinged coloration. As its common name suggests, the sicklefin lemon shark differs from its American counterpart in having more falcate (sickle-shaped) fins. This large species grows up to 3.8 m (12 ft) long. It generally inhabits water less than 92 m (302 ft) deep in a variety of habitats, from mangrove estuaries to coral reefs.

A slow-moving predator feeding mainly on bony fishes, the sicklefin lemon shark seldom travels long distances and many individuals can be found year-round at certain locations. Like other members of its family, this species is viviparous with females giving birth to as many as 13 pups every other year, following a gestation period of 10–11 months. Although they are potentially dangerous to humans and known to respond vigorously to any provocation, under normal circumstances sicklefin lemon sharks are cautious and tend to retreat if approached. The International Union for Conservation of Nature (IUCN) has assessed this species as Vulnerable; its low reproductive productivity and rate of movement limits the capacity of depleted stocks to recover. Off India and Southeast Asia, this species has been severely depleted or extirpated by unregulated exploitation for its meat, fins, and liver oil.

Did you know (auto-generated)

... 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 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?
... that Hixxy and Sharkey created a schism in the UK rave music scene in 1995?
... that the ampullae of Lorenzini enable sharks to sense electric fields?

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 spadenose shark exhibits the most advanced form of placental reproduction in fishes?
... that the dark, puffadder, brown, and Natal shysharks of South Africa are so named because they curl into a ring when threatened and "shyly" cover their eyes with their tails?
... that the daggernose shark can adjust the timing of events in its reproductive cycle by several months?
... that the lollipop catshark is shaped like a tadpole and has an almost gelatinous body?
... that the Australian swellshark can survive out of water for more than a day?

General images

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

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

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)

Wikimedia

The following Wikimedia Foundation sister projects provide more on this subject:

Commons
Free media repository
Wikibooks
Free textbooks and manuals
Wikidata
Free knowledge base
Wikinews
Free-content news
Wikiquote
Collection of quotations
Wikisource
Free-content library
Wikispecies
Directory of species
Wikiversity
Free learning tools
Wiktionary
Dictionary and thesaurus

Sources

Discover Wikipedia using portals

List of all portals

List of all portals
The arts portal

The arts portal
Biography portal

Biography portal
Current events portal

Current events portal
Geography portal

Geography portal
History portal

History portal
Mathematics portal

Mathematics portal
Science portal

Science portal
Society portal

Society portal
Technology portal

Technology portal
Random portal

Random portal
WikiProject Portals

WikiProject Portals

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.