Cow sharks are a shark family, the Hexanchidae, characterized by an additional pair or pairs of gill slits. Its 37 species are placed within the 10 genera: Gladioserratus, Heptranchias, Hexanchus, Notidanodon, Notorynchus, Pachyhexanchus, Paraheptranchias, Pseudonotidanus, Welcommia, and Weltonia.
The bluntnose sixgill shark, often simply called the cow shark, is the largest hexanchoid shark, growing to 20 ft (6.1 m) in length. It is found in tropical and temperate waters worldwide and its diet is widely varied by region.
The sixgill sharks are a genus, Hexanchus, of deepwater sharks in the family Hexanchidae. These sharks are characterized by a broad, pointed head, six pairs of gill slits, comb-like, yellow lower teeth, and a long tail. The largest species can grow up to 8 m long and weigh over 600 kg (1320 lb). They are continental shelf-dwelling and abyssal plain scavengers with a keen sense of smell and are among the first to arrive at carrion, together with hagfish and rattails. They show a characteristic rolling motion of the head when feeding.
The bigeyed sixgill shark is a cow shark of the family Hexanchidae. Its dorsal surface has a brownish-gray color, and is sharply separated from the light coloring of its ventral surface. The eyes are a fluorescent green while the shark is alive. The body of this shark is small, slim, and fusiform in shape. As the name suggests, this shark has six gill slits, unusual among most shark species. The head is narrow and somewhat flattened, and the mouth contains 5 rows of large, comb-shaped teeth. This shark's single dorsal fin is pushed back towards the caudal fin, and is behind the pelvic fins. The upper caudal fin is much longer than the lower, with a deep notch near the tip. All fins have thin white margins on the edge. In juveniles, the upper caudal fin has a black tip.
Polyopisthocotylea is a subclass of parasitic flatworms in the class Monogenea.
Pseudorhabdosynochus is a genus of monopisthocotylean monogeneans, included in the family Diplectanidae. The type-species of the genus is Pseudorhabdosynochus epinepheli .
The Diplectanidae are a family of monopisthocotylean monogeneans. They are all parasitic on the gills of fish. Diplectanids are small animals, generally around 1 mm in length. As parasites, they can be extremely numerous, up to several thousand on an individual fish.
Pseudorhabdosynochus epinepheli is a diplectanid monogenean parasitic on the gills of species of groupers. It is the type species of the genus Pseudorhabdosynochus Yamaguti, 1958.
Calydiscoides is a genus of monopisthocotylean monogeneans, included in the family Diplectanidae.
Louis Euzet was a French parasitologist.
Pseudorhabdosynochus americanus is a diplectanid monogenean parasitic on the gills of groupers. It was described as Diplectanum americanum by Price in 1937 and transferred to the genus Pseudorhabdosynochus by Kritsky and Beverley-Burton in 1986. The species was redescribed by Kritsky, Bakenhaster and Adams in 2015.
Pseudorhabdosynochus beverleyburtonae is a diplectanid monogenean parasitic on the gills of the dusky grouper, Epinephelus marginatus. It has been described by Guy Oliver in 1984 as Cycloplectanum beverleyburtonae, redescribed by Oliver in 1987, transferred to the genus Pseudorhabdosynochus by Kritsky & Beverley-Burton in 1986 as Pseudorhabdosynochus beverleyburtonae, redescribed by Kritsky, Bakenhaster and Adams in 2015, and redescribed in 2016 by Chaabane, Neifar, Gey & Justine.
Hexabothriidae is a family of monogenean parasites. The family name was proposed by Emmett W. Price in 1942. The family includes 14-16 genera according to authors and about 60 species; all are parasitic on the gills of chondrichthyan fishes.
Protocotyle is a genus of monogeneans in the family Hexabothriidae. The genus was created by Louis Euzet and Claude Maillard in 1974.
Lamellodiscus is a genus of monopisthocotylean monogeneans in the family Diplectanidae; all species of Lamellodiscus are small worms, parasitic on the gills of teleost fish.
Pseudorhabdosynochus oliveri is a diplectanid monogenean parasitic on the gills of the dusky grouper.
The Atlantic sixgill shark is a rare species of hexanchid shark found in the Atlantic Ocean at depths that are greater than 300 meters. These depths are known as mesopelagic and bathypelagic in tropical and temperate waters around the world. The Atlantic sixgill shark is very similar to other species of sixgill in terms of its growth rate in deep sea waters. It is believed that this is due to the abiotic and biotic factors in relation to the depths at which they are found. It was formerly described as its own species, but was synonymised with the bigeye sixgill shark. However, a study published in 2019 resurrected the species on the basis of molecular data. The species can be physically differentiated from the bluntnose sixgill shark by its much smaller size and position of the dorsal fin in relation to the caudal fin. The Atlantic sixgill shark becomes sexually mature at around 1.40 to 1.75 meters. They do not reach lengths much greater than 180 cm.
Pseudorhabdosynochus sosia is a diplectanid monogenean parasitic on the gills of groupers. It has been described in 2007 by Lassad Neifar & Louis Euzet. According to Neifar & Euzet, the name of the species refers to Sosia, who in Plautus’ comedy Amphitryon confronts his double, and to the resemblance of the vagina of P. sosia to that of P. beverleyburtonae.
Microcotyle donavini is a species of monogenean, parasitic on the gills of a marine fish. It belongs to the family Microcotylidae.
Sibitrema poonui is a species of monogenean flatworm, which is parasitic on the gills of a marine fish. It belongs to the family Gastrocotylidae.
