Cloudy catshark

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Cloudy catshark
Scyliorhinus torazame kanagawa.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Order: Carcharhiniformes
Family: Scyliorhinidae
Genus: Scyliorhinus
Species:
S. torazame
Binomial name
Scyliorhinus torazame
Scyliorhinus torazame distmap.png
Range of the cloudy catshark [2]
Synonyms

Catulus torazameTanaka, 1908
Scyliorhinus rudisPietschmann, 1908

Contents

The cloudy catshark (Scyliorhinus torazame) is a common species of catshark, belonging to the family Scyliorhinidae. It is a bottom-dweller that inhabits rocky reefs in the northwestern Pacific Ocean, from the shore to a depth of 320 m (1,050 ft). Growing up to 50 cm (20 in) long, this small, slim shark has a narrow head with a short blunt snout, no grooves between the nostrils and mouth, and furrows on the lower but not the upper jaw. It is also characterized by extremely rough skin and coloration consisting of a series of dark brown saddles along its back and tail, along with various darker and lighter spots in larger individuals.

The diet of the cloudy catshark consists of molluscs, crustaceans, and bony fishes. It is oviparous, with females laying encapsulated eggs two at a time in nursery areas. The claspers of the male bear numerous hooks that likely serve to facilitate copulation. This harmless shark can be readily maintained in captivity and is used as a model organism for biological research. It is caught incidentally, and generally discarded, by commercial fisheries. These activities do not appear to have negatively affected its population, leading it to be listed under Least Concern by the International Union for Conservation of Nature (IUCN).

Taxonomy

The original description of the cloudy catshark was published in 1908 by Shigeho Tanaka in the Journal of the Faculty of Science, University of Tokyo. He gave it the specific epithet torazame, which is its Japanese name (虎鮫, literally "tiger shark"), and assigned it to the genus Catulus. The type specimen was a 45 cm (18 in) long adult male caught off Misaki, Kanagawa, Japan. [3] Subsequent authors have synonymized Catulus with Scyliorhinus. [4]

Description

Large cloudy catsharks have light spots in addition to dark dorsal saddles Scyliorhinus torazame enoshima.jpg
Large cloudy catsharks have light spots in addition to dark dorsal saddles

The cloudy catshark reaches 50 cm (20 in) long and has a thin, deep, and firm body. The narrow head makes up slightly under one-sixth of the total length, and is two-thirds as wide as it is long. The snout is short and rounded. The large nostrils are preceded by small, triangular flaps of skin that do not reach the wide mouth. The medium-sized eyes are horizontally oval, equipped with rudimentary nictitating membranes (protective third eyelids), and followed by moderate spiracles. There are no grooves between the nostrils and the mouth. There are furrows extending from the corners of the mouth over the lower jaw only. The small teeth have a long central cusp typically flanked by two pairs of cusplets. The five pairs of gill slits are short, with the fourth pair over the pectoral fin origins. [4] [5]

The two dorsal fins are placed towards the back of the body, with the first originating over the rear of the pelvic fin bases. The first dorsal fin has a rounded apex and is larger than the second dorsal fin, which has a more angular shape. The pectoral and pelvic fins are moderate in size. In males, the inner margins of the pelvic fins are merged to form an "apron" over the long, cylindrical claspers. The origin of the anal fin lies approximately between the dorsal fins. The caudal peduncle is about as deep as the body, and leads to a low caudal fin with an indistinct lower lobe and a ventral notch near the tip of the upper lobe. The skin is thick and very rough due to the dermal denticles, which are large and upright with three backward-pointing teeth. This species is brown on the back and sides, with 610 indistinct darker dorsal saddles, and plain yellowish on its ventral side. Larger sharks also have many large, irregularly shaped light and dark spots. [4] [5]

Distribution and habitat

The cloudy catshark is common in the northwestern Pacific off Japan, Korea, China, and possibly the Philippines. [2] Bottom-dwelling in nature, this species can be found from the shore out to a depth of 320 m (1,050 ft) on the continental shelf and upper continental slope. [1] It favors rocky reefs and does not appear to be migratory. [6]

Biology and ecology

Egg capsules of the cloudy catshark with visible embryos Scyliorhinus torazame egg capsules.jpg
Egg capsules of the cloudy catshark with visible embryos

The cloudy catshark feeds primarily on molluscs, followed by crustaceans and bony fishes. [7] A predator of both this shark and its egg cases is the blotchy swell shark (Cephaloscyllium umbratile). [8] A known parasite of this species is the myxosporidian Chloromyxum scyliorhinum. [9] Reproduction is oviparous; adult females have a single functional ovary and two functional oviducts. [5] As a prelude to mating, the male bites at the female's pectoral fin, side, and gill region. Once he has a grip, he wraps his body around hers and inserts one of his claspers into her cloaca. Copulation may last between 15 seconds and 4 minutes. [10] The claspers of the male are unusual in that each has a row of around a hundred hooks running along the inner margin. These hooks likely serve to anchor the male to the female during copulation. [11] The female is capable of storing sperm within her nidamental gland (an organ that secretes egg cases) for many months. [12]

Females produce two mature eggs at a time, one per oviduct. The eggs are enclosed in smooth, translucent yellow, vase-shaped capsules measuring 1.9 cm (0.75 in) across and 5.5 cm (2.2 in) long. There are long tendrils at the four corners of the capsule. The eggs are laid in defined nursery areas: One such area is located at a depth of 100 m (330 ft) off Hakodate. When the embryo is 3.6 cm (1.4 in) long, it has external gills, undeveloped fins, and no pigmentation. At an embryonic length of 5.8 cm (2.3 in), the external gills have all but disappeared, and a covering of small denticles is present. By a length of 7.9 cm (3.1 in), the embryo has well-developed fins and pigmentation, and generally resembles the adult. [5] The eggs take 15 months to hatch at 11.3 °C (52.3 °F), and 79 months to hatch at 14.5 °C (58.1 °F). [6] The newly hatched shark measures 8 cm (3.1 in) long or more. [4] Maturation size tends to increase with decreasing water temperature: Off northerly Hakodate, both sexes mature at over 38 cm (15 in) long, while some females remain immature even at 47 cm (19 in) long. By contrast, off southerly Tsushima Island both sexes mature at around 33 cm (13 in) long. [5] [13] The maximum lifespan is at least 12 years. [6]

Human interactions

Several young cloudy catsharks at a public aquarium Scyliorhinus torazame shinagawa.jpg
Several young cloudy catsharks at a public aquarium

Harmless to humans, the cloudy catshark adapts well to captivity and has reproduced in the aquarium. [6] It is often used as a model organism in physiology research. [14] [15] On September 25, 1995, Masuda Motoyashi and colleagues used this species to perform the first successful artificial insemination of a shark or ray. [12] The cloudy catshark is caught incidentally by commercial fisheries with bottom fishing nets including trawls and gillnets, as well as on bottom longlines. Captured individuals are typically discarded, possibly with a high survival rate due to their hardiness. Some 40% of the fish discarded in Yamaguchi Prefecture fisheries are of this species. [1] The bottom trawl fishery operating off Fukushima Prefecture may catch over a ton of cloudy catsharks annually, which are also discarded. [16]

Despite heavy fishing pressure within its range, the cloudy catshark remains common, perhaps because it may be more biologically productive than most other sharks. As a result, it has been assessed as Least Concern by the International Union for Conservation of Nature (IUCN). [1] Cloudy catsharks from a number of locations off Japan have been found to be contaminated with polychlorinated biphenyls (PCBs) and dichlorodiphenyldichloroethylene (DDEs), which they acquire from their food. One likely source of these pollutants is the use of the pesticide DDT by developing nations in southern Asia. [17]

Related Research Articles

<span class="mw-page-title-main">Scyliorhinidae</span> Family of fishes

Scyliorhinidae is a family of sharks, one of a few families whose members share the common name catsharks, belonging to the order Carcharhiniformes, the ground sharks. Although they are generally known as catsharks, some species can also be called dogfish due to previous naming. However, a dogfish may generally be distinguished from a catshark as catsharks lay eggs while dogfish have live young. Like most bottom feeders, catsharks feed on benthic invertebrates and smaller fish. They are not harmful to humans. The family is paraphyletic, containing several distinct lineages that do not form a monophyletic group.

<span class="mw-page-title-main">Chain catshark</span> Species of shark

The chain catshark or chain dogfish is a small, reticulated catshark that is biofluorescent. The species is common in the Northwest Atlantic, Gulf of Mexico, and Caribbean. It is harmless and rarely encountered by humans. It has very similar reproductive traits to the small-spotted catshark.

<i>Cephaloscyllium</i> Genus of sharks

Cephaloscyllium is a genus of catsharks, and part of the family Scyliorhinidae, commonly known as swellsharks because of their ability to inflate their bodies with water or air as a defense against predators. These sluggish, bottom-dwelling sharks are found widely in the tropical and temperate coastal waters of the Indian and Pacific Oceans. They have stocky, spindle-shaped bodies and short, broad, and flattened heads. The mouth is capacious, containing many small teeth and lacking furrows at the corners. The two dorsal fins are placed far back on the body, with the first much larger than the second. Different species have various color patterns of saddles, blotches, reticulations, and/or spots. The largest members of the genus can grow over 1 m (3.3 ft) in length. Swellsharks prey on a variety of fishes and invertebrates, and are oviparous, with females producing egg capsules in pairs. They are harmless and have been deemed of having no commercial value.

<span class="mw-page-title-main">Draughtsboard shark</span> Species of shark

The draughtsboard shark is a species of catshark, and part of the family Scyliorhinidae, so named for its "checkerboard" colour pattern of dark blotches. It is endemic to New Zealand, where it is also known as the carpet shark. This shark typically reaches 1 m (3.3 ft) in length and has a thick body with a broad, flattened head and a capacious mouth. Its two dorsal fins are placed far back on the body, with the first much larger than the second.

<span class="mw-page-title-main">Balloon shark</span> Species of shark

The balloon shark is a species of catshark, and part of the family Scyliorhinidae, endemic to the southwestern Indian Ocean off South Africa and Mozambique. Benthic in nature, it is found over sandy and muddy flats at depths of 40–600 m (130–1,970 ft). This thick-bodied species has a broad, flattened head and a short tail; its distinguishing traits include narrow, lobe-like skin flaps in front of the nostrils, and a dorsal color pattern of faint darker saddles on a light grayish background.

<span class="mw-page-title-main">Blotchy swellshark</span> Species of shark

The blotchy swellshark or Japanese swellshark is a common species of catshark, belonging to the family Scyliorhinidae. The Blotchy swellshark is found at depths of 90–200 m (300–660 ft) in the northwestern Pacific Ocean, from Japan to Taiwan. It is benthic in nature and favors rocky reefs. Reaching 1.4 m (4.6 ft) in length, this thick-bodied shark has a broad head, large mouth, and two unequally-sized dorsal fins positioned far back past the pelvic fins. It can be identified by its dorsal coloration, consisting of seven brown "saddles" and extensive darker mottling on a light tan background. This species has often been confounded with the draughtsboard shark and the Sarawak pygmy swellshark in scientific literature.

<span class="mw-page-title-main">Coral catshark</span> Species of shark

The coral catshark is a species of coloured catshark belonging to the family Atelomycteridae. It is common on shallow coral reefs across the Indo-West Pacific, from Pakistan to New Guinea. Reaching up to 70 cm (28 in) in length, the coral catshark has an extremely slender body, a short head and tail, and two dorsal fins that are angled backwards. It can be identified by the numerous black and white spots on its back, sides, and fins, which often merge to form horizontal bars. Furthermore, adult males have distinctively long and thin claspers.

<span class="mw-page-title-main">Izak catshark</span> Species of catshark, of the family Scyliorhinidae

The Izak catshark or simply Izak is a species of shark belonging to the family Pentanchidae, the deepwater catsharks. This species is common off the coasts of South Africa and southern Namibia. It typically inhabits the outer continental shelf at depths of 100–300 m (330–980 ft), with the males found deeper than the females and juveniles. The Izak catshark has a short, wide, flattened head and a robust body tapering to a long, slender tail. It can be identified by its ornate color pattern of dark brown spots or reticulations and blotches on a light yellowish background, as well as by the enlarged dermal denticles over its pectoral fins and along its dorsal midline from the snout to the second dorsal fin. This species reaches 69 cm (27 in) in length, with the males larger than females.

<span class="mw-page-title-main">Quagga catshark</span> Species of fish

The quagga catshark is a species of shark belonging to the family Pentanchidae, the deepwater catsharks. A small, slim-bodied shark reaching 37 cm (15 in) in length, it has a distinctive color pattern of narrow, dark brown vertical bars, which resemble those of the quagga. Its head is short and flattened, with a pointed snout tip that is not upturned.

<span class="mw-page-title-main">Tiger catshark</span> Species of shark

The tiger catshark is a species of shark belonging to the family Pentanchidae, the deepwater catsharks. It is found over sandy areas and near reef peripheries off South Africa and perhaps Mozambique, from close to shore to usually no deeper than 100 m (330 ft). Reaching a length of 50 cm (20 in), this small, slim shark has a broad, flattened head with an upturned snout tip. It can additionally be identified by its dorsal colour pattern of ten dark brown saddles on a yellowish brown background.

<span class="mw-page-title-main">Freckled catshark</span> Species of shark

The freckled catshark is a catshark of the family Scyliorhinidae. It is found on the continental shelf and upper slope from the western Atlantic from western Venezuela, Suriname, Brazil, and Uruguay, between latitudes 11° N and 32° S. However, specimens from the northern part of this range probably refer to other species.

<span class="mw-page-title-main">Blackmouth catshark</span> Species of shark

The blackmouth catshark is a species of deepwater catshark, belonging yo the family Pentanchidae, common in the northeastern Atlantic Ocean from Iceland to Senegal, including the Mediterranean Sea. It is typically found over the continental slope at depths of 150–1,400 m (490–4,590 ft), on or near muddy bottoms. The youngest sharks generally inhabit shallower water than the older juveniles and adults. This slim-bodied species is characterized by the black interior of its mouth, a marbled pattern of pale-edged brownish saddles or blotches along its back and tail, and a prominent saw-toothed crest of enlarged dermal denticles along the upper edge of its caudal fin. It reaches lengths of 50–79 cm (20–31 in), with sharks in the Atlantic growing larger than those in the Mediterranean.

<span class="mw-page-title-main">Australian sawtail catshark</span> Species of shark

The Australian sawtail catshark is a common species of deepwater catshark, belonging to the family Pentanchidae, endemic to southern Australian waters. It is found on or near the bottom of the outer continental shelf and upper continental slope, at depths of 85 to 823 m. This slim-bodied species is characterized by crests of enlarged dermal denticles along both the dorsal and ventral edges of its caudal fin and caudal peduncle, along with a color pattern of broad, dark saddles outlined in white. It can grow to 61 cm (24 in) in length. The Australian sawtail catshark feeds mainly on fishes, crustaceans, and cephalopods. Females are oviparous and lay eggs enclosed by capsules. This species is often caught incidentally by commercial bottom trawl fisheries, but is not significantly threatened by fishing activity. Thus, it has been assessed as of Least Concern by the International Union for Conservation of Nature (IUCN).

<span class="mw-page-title-main">Southern sawtail catshark</span> Species of shark

The southern sawtail catshark is a species of deepwater catshark, belonging to the family Pentanchidae, endemic to southern Brazil. It inhabits deepwater reefs on the upper continental slope at a depth of 236–600 m (774–1,969 ft). Reaching at least 43 cm (17 in) in length, this slim-bodied species closely resembles the Antilles catshark. It has a prominent crest of enlarged dermal denticles along the dorsal edge of the caudal fin, as well as a distinctive color pattern of dark oval blotches, outlined in white, along its back. The southern sawtail catshark is oviparous, with females producing reddish egg capsules. The International Union for Conservation of Nature (IUCN) has assessed it as Vulnerable; it is often taken as bycatch and may be threatened by intensifying squid fishing.

<span class="mw-page-title-main">Broadfin sawtail catshark</span> Species of shark

The broadfin sawtail catshark is a species of shark belonging to the family Pentanchidae, the deepwater catsharks. It is found on or near the bottom at depths of 150–540 m (490–1,770 ft), from southeastern Japan to the East China Sea. A slender species growing to 68 cm (27 in) long, this shark is characterized by a fairly long, pointed snout, a series of indistinct, dark saddles along its back and tail, and a prominent crest of enlarged dermal denticles along the dorsal edge of its caudal fin. In addition, adult males have very long claspers that reach past the anal fin. The broadfin sawtail catshark is an opportunistic predator of bony fishes, cephalopods, and crustaceans, with immature and mature sharks being primarily piscivorous. It is oviparous and reproduces year-round.

<span class="mw-page-title-main">Blacktip sawtail catshark</span> Species of shark

The blacktip sawtail catshark is a species of shark belonging to the family Pentanchidae, the deepwater catsharks, This species is found off the coasts of Taiwan and the Philippines. It is demersal in nature and occurs deeper than 60 m (200 ft). Growing up to 46 cm (18 in) long, this slim-bodied species is characterized by its plain brownish dorsal coloration with dark tips on the dorsal and caudal fins, and a prominent crest of enlarged dermal denticles on the upper edge of the caudal fin. It is oviparous, with females producing encapsulated eggs two at a time year-round. The blacktip sawtail catshark is caught incidentally in bottom trawls and used for fishmeal in Taiwan.

<span class="mw-page-title-main">Arabian carpetshark</span> Species of shark

The Arabian carpetshark is a species of carpet shark in the family Hemiscylliidae, inhabiting coral reefs and other shallow coastal habitats from the Persian Gulf to India. Reaching 78 cm (31 in) long, this shark is characterized by a slender, plain brown body, and by two dorsal fins with straight trailing margins and the second smaller but longer-based than the first. The Arabian carpetshark feeds on bony fishes and invertebrates. Reproduction is oviparous with an annual cycle; females deposit egg capsules four at a time and the young hatch after 70–80 days. This small shark is often captured as bycatch but rarely used by humans. It has been assessed as Near Threatened by the International Union for Conservation of Nature (IUCN), as there is increasing fishing pressure and habitat degradation within its range. It does well in aquariums and has been bred in captivity.

The whitefin swellshark is a species of catshark, belonging to the family Scyliorhinidae, endemic to southeastern Australia. It is found 126–554 m (413–1,818 ft) down, on the outer continental shelf and upper continental slope. Reaching 1.1 m (3.6 ft) in length, this shark has a very thick body and a short, broad, flattened head with a large mouth. It is characterized by a dorsal color pattern of dark saddles and blotches over a brown to gray background, and light fin margins. When threatened the whitefin swellshark can inflate itself with water or air to increase its size. Reproduction is oviparous. As of 2019 The International Union for Conservation of Nature (IUCN) has assessed this species as Critically Endangered due to the significant decline of the population.

<i>Scyliorhinus meadi</i> Species of shark

Scyliorhinus meadi, the blotched catshark, is a little-known species of catshark, and part of the family Scyliorhinidae, found in the western central Atlantic Ocean. It inhabits banks of deep-sea coral at depths of 329–548 m (1,079–1,798 ft), feeding on cephalopods, shrimp, and bony fishes. This species can be identified by its wide body and head, and the dark saddle-like markings on its back. It also has small spots that fluoresce yellow under a blue light. Adult blotched catsharks have not been observed; the largest immature specimen is 49 cm (19 in) long. Like other catsharks, it is believed to be oviparous. This species is not dangerous to humans and has no commercial significance.

<span class="mw-page-title-main">Cinder cloudy catshark</span> Species of shark

The cinder cloudy catshark is a species of catshark from the Pacific Ocean; all specimens identified have been from the area around the Izu Islands, Japan. The species is a close relative of the cloudy catshark, and the overall appearance is similar. The species was first identified in 2022 as bycatch of the splendid alfonsino fishery.

References

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  12. 1 2 Motoyasu, M.; I. Yoshiyuki; K. Shigenori; I. Haruyuki & I. Tooru (2003). "Artificial insemination of the cloudy catshark". Journal of Japanese Association of Zoological Gardens and Aquariums. 44 (2): 39–43. Archived from the original on 2012-03-13. Retrieved 2010-12-15.
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