Portal:Sharks

Welcome to the shark portal

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 (or Selachimorpha) and are the sister group to the Batoidea (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 (selachimorphs) 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...)

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The Philadelphia Inquirer reported the capture of a "man-eating" shark off the Jersey Shore after the attacks

The Jersey Shore shark attacks of 1916 were a series of shark attacks along the coast of New Jersey between July 1 and July 12, 1916, in which four people were killed and one injured. Since 1916, scholars have debated which shark species was responsible and the number of animals involved, with the great white shark and the bull shark most frequently being blamed. The attacks occurred during a deadly summer heat wave and polio epidemic in the northeastern United States that drove thousands of people to the seaside resorts of the Jersey Shore. Shark attacks on the Atlantic Coast of the United States outside the semitropical states of Florida, Georgia, and the Carolinas were rare, but scholars believe that the increased presence of sharks and humans in the water led to the attacks in 1916.

Local and national reaction to the attacks involved a wave of panic that led to shark hunts aimed at eradicating the population of "man-eating" sharks and protecting the economies of New Jersey's seaside communities. Resort towns enclosed their public beaches with steel nets to protect swimmers. Scientific knowledge about sharks before 1916 was based on conjecture and speculation. The attacks forced ichthyologists to reassess common beliefs about the abilities of sharks and the nature of shark attacks.

The Jersey Shore attacks immediately entered into American popular culture, where sharks became caricatures in editorial cartoons representing danger. The attacks inspired Peter Benchley's novel Jaws (1974), an account of a great white shark that torments the fictional coastal community of Amity. Jaws was made into an influential film in 1975 by Steven Spielberg. The attacks became the subject of documentaries for the History Channel, Discovery Channel, and National Geographic Channel.

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... that the ampullae of Lorenzini enable sharks to sense electric fields?
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... that a shark cost a competitor a silver medal in the spearfishing event at the 2014 Micronesian Games?
... that Hixxy and Sharkey created a schism in the UK rave music scene in 1995?

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Credit: Terry Goss

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

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... that the taillight shark has a gland on its belly that releases clouds of luminescent blue fluid?
...that the Jersey Shore shark attacks of 1916 killed four people and inspired Peter Benchley's novel Jaws (1974)?
... that the presence of the rare bigeye sand tiger in the Pacific Ocean was first suspected based on teeth recovered from the ocean floor?
... that the rough skin of the nursehound was once used as an abrasive called "rubskin", which cost a hundred times more than sandpaper?
... that the epaulette shark can survive for an hour without oxygen?

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

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