| Small-spotted catshark | |
|---|---|
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Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Division: | Selachii |
| Order: | Carcharhiniformes |
| Family: | Scyliorhinidae |
| Genus: | Scyliorhinus |
| Species: | S. canicula |
| Binomial name | |
| Scyliorhinus canicula | |
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| Range in blue | |
Thesmall-spotted catshark (Scyliorhinus canicula), also known as thesandy dogfish,[2]lesser-spotted dogfish,rough-hound ormorgay (in Scotland and Cornwall),[3] is acatshark of thefamilyScyliorhinidae. It is found on thecontinental shelves and the uppermost continental slopes off the coasts ofNorway and theBritish Isles south toSenegal and in theMediterranean, between latitudes63° N and12° N. It can grow up to a length of 1 m (3 ft 3 in), and it can weigh more than 2 kg (4.4 lb).[4] It is found primarily over sandy, gravelly, or muddy bottoms from depths of a few metres down to 400 m (1,300 ft).[5]S. canicula is one of the most abundantelasmobranchs in the northeast Atlantic and Mediterranean Sea. The majority of the populations are stable in most areas.[6]
S. canicula are small, shallow-water sharks with a slender body and a blunt head. The two dorsal fins are located towards the tail end of the body. The texture of their skin is rough, similar to the coarseness of sandpaper.[7] The nostrils are located on the underside of the snout and are connected to the mouth by a curved groove. The upper side of the body is greyish brown with dark brown spots. The underside is a light greyish white. The teeth ofS. canicula are larger in males than in females; in addition, maleS. canicula from West African waters have stronger, larger, and more calcinated jaws. The differences in mouth dimensions and tooth length between males and females, and between immature and adult males, could be due to different feeding habits or adaptations for reproductive behaviour.[8]
S. canicula isoviparous. They depositegg cases protected by a horny capsule with long tendrils. Egg cases are mostly deposited on macroalgae in shallow coastal waters. When the egg cases are deposited farther from shore, they are placed on sessile erect invertebrates. Egg cases usually measure 4 cm by 2 cm, without ever exceeding 6 cm (2.4 in).[9] These egg cases can be found around the coasts of Europe. The embryos develop for 5–11 months depending on the sea temperature, and the young are born with a measurement of 9–10 cm (3.5–3.9 in).
Spawning can take place almost year round.[9] However, there can be seasonal patterns in spawning activity as well. For example,S. canicula females located off the Mediterranean coast of France lay their eggs from March to June and in December. In the waters surrounding Great Britain, egg laying occurs in spring with a gap between August and October. On the Tunisian coast, the sharks lay their eggs starting in spring, peaking in the summer and then slightly decreasing during autumn.[10] Males reach sexual maturity with a length of about 37.1–48.8 cm (14.6–19.2 in). Females reach sexual maturity with a length of 36.4–46.7 cm (14.3–18.4 in).[11]
S. canicula is anopportunistic species, preying on a wide variety of organisms. Decapod crustaceans, molluscs and fishes are their main prey, butechinoderms,polychaetes,sipunculids andtunicates may also be eaten.[5] Dietary preferences change with age; younger animals prefer small crustaceans, while older animals prefer hermit crabs and molluscs. Feeding intensity is highest during the summer due to the higher availability of prey life. Diet composition varies with body size.
There are no significant differences in feeding habits between male and femaleS. canicula.[5]Juveniles ofS. canicula feed by anchoring the prey item on thedermal denticles near their tail, and tearing bite-sized pieces off with rapid head and jaw movements, a behaviour known as "scale rasping". Use of dermal denticles to assist in feeding was first documented in this species.[12]
A study published in 2014 atExeter University showed that individual small-spotted catsharks have differentpersonality traits. Some individuals are more sociable than others, some more aggressive, some more exploratory in nature.[13][14]
S. canicula is well-suited for comparative analysis ofgastrulation for several reasons.
S. canicula is one of the most abundant elasmobranchs in the northeast Atlantic and Mediterranean. It is regularly caught by near-shore fisheries, but the majority taken by commercial fishermen and recreational anglers are discarded. Studies have shown that post-discard survival rates are extremely high, around 98%. Although localized depletion may have occurred in some areas, surveys have shown that populations are stable or are even increasing throughout the majority of its range. However, continued monitoring of landing and discarded data is important to avoid any future decline.
This species is currently listed as being ofleast concern on theIUCN Red List of Threatened Species, because there is no evidence to indicate that the global population has declined significantly. Since 2003, there have been yearly releases of these sharks into theGullmarn fjord in Sweden by the public aquaria Havets Hus inLysekil. More than 90 sharks have been released since 2003, of which one was found in southern Norway 10 years after its release. This means that these sharks can reach at least an age of 14 years.[16]
S. canicula is currently of low commercial value. In the recent past, it was one of the species sold in English and Scottishfish and chip shops asrock salmon, rock eel, huss, or sweet william. In other parts of its range, it is occasionally baked or used infish soup.[3] Its hard skin has been used as a substitute forpumice, but the fact that catsharks have to be skinned before they can be filleted discourages commercial fishermen from catching this species.[17]
Media related toScyliorhinus canicula at Wikimedia Commons
Data related toScyliorhinus canicula at Wikispecies
