Nursehound

The first scientific description of the nursehound was published by Carl Linnaeus, in the 1758 tenth edition of Systema Naturae. He gave it the name Squalus stellaris, the specific epithet stellaris being Latin for "starry". No type specimen was designated. In 1973, Stewart Springer moved this species to the genus Scyliorhinus. The common name "nursehound" came from an old belief by English fishermen that this shark attends to its smaller relatives, while the name "huss" may have come from a distortion of the word "nurse" over time. ==Distribution and habitat==

The nursehound is found in the northeastern Atlantic from southern Norway and Sweden to Senegal, including off the British Isles, throughout the Mediterranean Sea, and the Canary Islands. It may occur as far south as the mouth of the Congo River, though these West African records may represent misidentifications of the West African catshark (S. cervigoni). Its range seems to be rather patchy, particularly around offshore islands, where there are small local populations with limited exchange between them. ==Description==

The nursehound attains a length of , though most measure less than . The five pairs of gill slits are small, with the last two over the pectoral fin bases. The two dorsal fins are placed far back on the body; the first is larger than the second and originates over the bases of the pelvic fins. The pectoral fins are large. In males, the inner margins of the pelvic fins are merged into an "apron" over the claspers. The caudal fin is broad and nearly horizontal, with an indistinct lower lobe. The skin is very rough, due to a covering of large, upright dermal denticles. The nursehound has small black dots covering its back and sides, interspersed with brown spots of varying shapes larger than the pupil, on a grayish or brownish background. The pattern is highly variable across individuals and ages; there may also be white spots, or the brown spots may be expanded so that almost the whole body is dark, or a series of faint "saddles" may be present. The underside is plain white. ==Biology and ecology==

Primarily nocturnal, nursehounds spend the day inside small holes in rocks and swim into deeper water at night to hunt. Sometimes two sharks will squeeze into the same hole, and several individuals will seek out refuges within the same local area. In one tracking study, a single immature nursehound was observed to use five different refuges in succession over a period of 168 days, consistently returning to each one over a number of days before moving on. Nursehounds may occupy refuges to hide from predators, avoid harassment by mature conspecifics, and/or to facilitate thermoregulation. In captivity, these sharks are gregarious and tend to rest in groups, though the individuals comprising any particular group changes frequently. This species is less common than the small-spotted catshark. the tapeworm Acanthobothrium coronatum, the trypanosome Trypanosoma scyllii, the isopod Ceratothoa oxyrrhynchaena, and the copepod Lernaeopoda galei. The netted dog whelk (Nassarius reticulatus) preys on the nursehound's eggs by piercing the case and extracting the yolk. Adults move into shallow water in the spring or early summer, and mate only at night. Eggs in the North Sea and the Atlantic take 10–12 months to hatch, while those from the southern Mediterranean take 7 months to hatch. The length at hatching is off Britain, and off France. Newly hatched sharks grow at a rate of per day, and have prominent saddle markings. Sexual maturity is attained at a length of , which corresponds to an age of four years if hatchling growth rates remain constant. This species has a lifespan of at least 19 years. ==Human interactions==

Nursehounds are generally harmless to humans. However, 19th-century British naturalist Jonathan Couch noted that "although not so formidable with its teeth as many other sharks, this fish is well able to defend itself from an enemy. When seized it throws its body round the arm that holds it, and by a contractile and reversed action of its body grates over the surface of its enemy with the rugged spines of its skin, like a rasp. There are few animals that can bear so severe an infliction, by which their surface is torn with lacerated wounds." This shark is displayed by many public aquariums and has been bred in captivity. The liver was also used as a source of oil, and the carcasses cut up and used to bait crab traps. The meat of this species is marketed fresh or dried and salted, though it is considered "coarse" in some quarters. In France, it is sold as grande roussette or saumonette, as after being skinned and beheaded it resembles salmon. This species is also sometimes processed into fishmeal, or its fins dried and exported to the Asian market. In European waters, commercial production of this species is led by France, followed by the UK and Portugal; it is caught using bottom trawls, gillnets, bottom set longlines, handlines and fixed bottom nets. In 2004, a total catch of 208 tons was reported from the northeastern Atlantic. The impact of fishing activities on the nursehound is difficult to assess as species-specific data is generally lacking. This species is more susceptible to overfishing than the small-spotted catshark because of its larger size and fragmented distribution, which limits the recovery potential of depleted local stocks. There is evidence that its numbers have declined significantly in the Gulf of Lion, off Albania, and around the Balearic Islands. These declines have led the International Union for Conservation of Nature (IUCN) to list the nursehound as Vulnerable. ==References==