The Hexanchiformes are the order consisting of the most primitive types of sharks, and numbering just seven extant species. Fossil sharks that were apparently very similar to modern sevengill species are known from Jurassic specimens.
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 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.
Microcotyle is a genus which belongs to the phylum Platyhelminthes and class Monogenea. Species of Microcotyle are ectoparasites that affect their host by attaching themselves as larvae on the gills of the fish and grow into adult stage. This larval stage is called oncomiracidium, and is characterized as free swimming and ciliated.
Protocotyle euzetmaillardi is a species of monogenean of the family Hexabothriidae.
Lethrinus rubrioperculatus, common names the spotcheek emperor, red-eared emperor, red-ears, red-edged emperor, scarlet-cheek emperor, and spot cheek emperor, is a species of emperor fish.
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.
Calydiscoides is a genus of monopisthocotylean monogeneans, included in the family Diplectanidae.
Louis Euzet was a French parasitologist.
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.
Echinoplectanum is a genus of monopisthocotylean monogeneans in the family Diplectanidae. All its species are parasites on the gills of fish; hosts recorded to date are all groupers, including coralgroupers and the Dusky grouper. So far, species of Echinoplectanum have been recorded only from fish caught off Australia, New Caledonia and in the Mediterranean Sea.
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 .
Jean-Lou Justine, French parasitologist and zoologist, is a professor at the National Museum of Natural History in Paris, France, and a specialist of fish parasites and invasive land planarians.
Protolamellodiscus is a genus of monopisthocotylean monogeneans in the family Diplectanidae. All species of Protolamellodiscus are parasites of marine perciform fishes of the families Lethrinidae, Nemipteridae, Serranidae and Sparidae.
Atriasterinae is a subfamily within family Microcotylidae and class Monogenea. This subfamily was created by Maillard & Noisy in 1979.
