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 and are the sister group to the Batoidea. Some sources extend the term "shark" as an informal category including extinct members of Chondrichthyes with a shark-like morphology, such as hybodonts and xenacanths. Shark-like chondrichthyans such as Cladoselache and Doliodus first appeared in the Devonian Period, though some fossilized chondrichthyan-like scales are as old as the Late Ordovician. The oldest modern sharks (selachians) are known from the Early Jurassic, about 200 Ma.
Carcharhiniformes, the ground sharks, are the largest order of sharks, with over 270 species. They include a number of common types, such as catsharks, swellsharks, and the sandbar shark.
A sawshark or saw shark is a member of a shark order bearing a unique long, saw-like rostrum edged with sharp teeth, which they use to slash and disable their prey. There are eight species within the Pristiophoriformes, including the longnose or common sawshark, shortnose sawshark, Japanese sawshark, Bahamas sawshark, sixgill sawshark, African dwarf sawshark, Lana's sawshark and the tropical sawshark.
The whale shark is a slow-moving, filter-feeding carpet shark and the largest known extant fish species. The largest confirmed individual had a length of 18.8 m (61.7 ft). The whale shark holds many records for size in the animal kingdom, most notably being by far the largest living nonmammalian vertebrate. It is the sole member of the genus Rhincodon and the only extant member of the family Rhincodontidae, which belongs to the subclass Elasmobranchii in the class Chondrichthyes. Before 1984 it was classified as Rhiniodon into Rhinodontidae.
The Lamniformes are an order of sharks commonly known as mackerel sharks. It includes some of the most familiar species of sharks, such as the great white, as well as more unusual representatives, such as the goblin shark and megamouth shark.
The angelsharks are a group of sharks in the genus Squatina of the family Squatinidae. They commonly inhabit sandy seabeds close to 150 m (490 ft) in depth. Many species are now classified as critically endangered by the International Union for Conservation of Nature. Once common over large areas of the Northeast Atlantic from Norway, Sweden, Morocco and the Canary Islands, to the Mediterranean and Black Seas, there is now significant fishing pressure which has resulted in significant population decline.
Thresher sharks are large lamniform sharks of the family Alopiidae found in all temperate and tropical oceans of the world; the family contains three extant species, all within the genus Alopias.
Bait fish are small-sized fish caught and used by anglers as bait to attract larger predatory fish, particularly game fish. Baitfish species are typically those that are common and breed rapidly, making them easy to catch and in abundant supply.
The crocodile shark is a species of mackerel shark and the only extant member of the family Pseudocarchariidae. A specialized inhabitant of the mesopelagic zone, the crocodile shark can be found worldwide in tropical waters from the surface to a depth of 590 m (1,940 ft). It performs a diel vertical migration, staying below a depth of 200 m (660 ft) during the day and ascending into shallower water at night to feed. Typically measuring only 1 m (3.3 ft) in length, the crocodile shark is the smallest living mackerel shark. It can be distinguished by its elongated cigar-shaped body, extremely large eyes, and relatively small fins.
The Hemiscylliidae are a family of sharks in the order Orectolobiformes, commonly known as longtail carpet sharks and sometimes as bamboo sharks. They are found in shallow waters of the tropical Indo-Pacific.
The Taiwan saddled carpetshark is a carpetshark of the family Parascylliidae found around Taiwan, between latitudes 28°N and 21°N, at depths to 110 m. Its length is up to 39 cm.
The saddle carpetshark is a carpet shark of the family Parascylliidae found around Japan, between latitudes 35°N and 24°N, at depths between 250 and 290 m. The saddle carpetshark is known to grow up to 49 cm (19 in) in length, and it is an oviparous.
The rusty carpetshark is a carpetshark of the family Parascylliidae found off southern Australia between latitudes 31°S and 41°S near the ocean floor on the continental shelf. It inhabits rocky reefs and seagrass beds 5–150 m (16–492 ft) in depth by night, hiding in caves by day. Its length is up to 80 cm (2.6 ft) TL and it feeds on crustaceans and molluscs. Reproduction is oviparous, with pups being born at 17 cm (6.7 in) in length.
The collared carpetshark is a poorly understood species of carpetshark of the family Parascylliidae endemic to the waters of eastern Australia between latitudes 26°S and 38°S. It is typically found 55–128 m (180–420 ft) in depth near the floor of rocky reefs on the continental shelf, though its depth range can extend between 20 and 230 m. At a maximum length of only 85 cm (2.79 ft), it poses no threat to humans. It is common within its range and is not targeted species. This, combined with high survival rates after discardment and a significant portion of habitat untouched by fishing are why it is listed as Least Concern by the International Union for Conservation of Nature (IUCN). Reproduction is oviparous and embryos feed solely on yolk.
The necklace carpetshark, also known as the varied carpetshark, is a carpetshark of the family Parascylliidae endemic to the waters off Australia's southern coast between latitudes 37°S and 41°S. It is found near the ocean floor over sand, rock, coral reefs, and kelp and seagrass beds at depths down to 180 m (590 ft). It is almost exclusively seen at night and spends the day hidden in caves or camouflaged on the ocean floor.
Parascyllium is a genus of carpetsharks in the family Parascylliidae. Species in this genus are distributed in waters around Australia.
Batoidea is a superorder of cartilaginous fishes, commonly known as rays. They and their close relatives, the sharks, comprise the subclass Elasmobranchii. Rays are the largest group of cartilaginous fishes, with well over 600 species in 26 families. Rays are distinguished by their flattened bodies, enlarged pectoral fins that are fused to the head, and gill slits that are placed on their ventral surfaces.
The elongate carpet shark is a species of carpetshark in the family Parascylliidae. It is known from a single female specimen 42.1 cm (16.6 in) long, recovered from the stomach of a school shark caught from a depth of 50 m (160 ft) off Chatham Island, Western Australia. It was described by P.R. Last and J.D. Stevens in 2008.
Cirrhoscyllium is a genus of carpetsharks in the family Parascylliidae.
Galeomorphii is a superorder of cartilaginous fishes which includes all modern sharks except the dogfish and its relatives. They are sometimes called galea or galean sharks. There are about 300 living species in 23 families. Galean sharks are divided into four orders: the Heterodontiformes, Orectolobiformes, Lamniformes, and Carcharhiniformes
