Swell shark

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Swell shark
Swell Shark, San Clemente Island, California.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Subdivision: Selachimorpha
Order: Carcharhiniformes
Family: Scyliorhinidae
Genus: Cephaloscyllium
Species:
C. ventriosum
Binomial name
Cephaloscyllium ventriosum
(Garman, 1880)
Synonyms
  • Scyllium ventriosum(Garman, 1880)
  • Cephaloscyllium uter(Jordan & Gilbert, 1896)
  • Catulus uter(Jordan & Gilbert, 1896))

The swell shark (Cephaloscyllium ventriosum) is a catshark in the family Scyliorhinidae. It is found in the tropical and subtropical eastern Pacific Ocean from between central California to southern Mexico, with an additional population off the coast of Chile. [1] As a defense, the swell shark is able to expand to approximately double its regular size by swallowing water.

Contents

Taxonomy

When discovered in 1880, the swell shark was first described as Scyllium ventriosum, but was later changed to Cephaloscyllium ventriosum. The genus name comes from the Greek word kephale, which means "head", and skylla, which means a certain kind of shark. The species name comes from the Latin word ventrĭōsus, which means "large-bellied". The species name refers to its ability to enlarge itself by taking in water. [2]

Distribution and habitat

The swell shark is found in the eastern Pacific Ocean, from the central California coast to southern Mexico. [1] [2] There is an additional population off the coast of Chile. [2] [3] It can be found between the depths of 5 m and 457 m, but is most common between 5 m and 37 m. [2] [1]

Swell sharks are often found over algae-covered rocky bottoms where it hides in crevices during the day. [2]

Description

Swell sharks are typically around 90 cm in length, with a maximum length of 110 cm. [2] [3] They have flat, broad heads with large gold eyes that have nictitating eyelids. [2] Swell sharks have a yellow-brown coloration, with brown and white spots. [2] The spots cover their underside, but are not present on their fins. [2] Usually the younger sharks are lighter in color than the adults. [2] The gills of a swell shark are usually very small and tight. [2]

Every swell shark has around 55–60 teeth. [2] Teeth typically have three smooth cusps, but can have as many as five cusps. [2] The middle cusp is the longest. [2]

Ecology

Swell sharks are nocturnal and sleep in rock crevices during the day, where their appearance allows them to be camouflaged. [2] They are very sociable and are commonly seen sleeping next to or on top of other sharks. [4] [3]

Reproduction

Egg case with yolk Swell shark egg channel islands2.jpg
Egg case with yolk

The swell shark is oviparous, laying two green or amber flattened eggs at a time. [1] [3] Fertilization occurs internally. [5] The egg cases become attached to kelp or the reef with tendrils. It has been suggested that the length of the tendrils depends on the amount of surf action the region is under. [4] After producing the egg case, no parental care is provided. [5] The egg case which contains the embryo is approximately 2.5 centimeters (0.98 in)–5.1 centimeters (2.0 in) by 7.6 centimeters (3.0 in)–13 centimeters (5.1 in). [2] The embryos will feed solely on yolk before they hatch. [3] The gestation time depends on water temperature but is typically between 9–12 months. [5] Pups have a double row of enlarged dermal denticles to help them exit the eggcase. [4] [5] After hatching, the pup is approximately 15 cm in length and is fully self-sufficient. [4] [5]

Diet

Juvenile swell shark bending into a U-shape Cephaloscyllium ventriosum juvenile.jpg
Juvenile swell shark bending into a U-shape

Swell sharks hunt at night for bony fish, molluscs, and crustaceans. [2] [3] They will eat prey that is dead or alive. [3] They feed either by sucking prey into their mouth or by waiting motionless on the sea floor with their mouth open, waiting to encounter prey. [2] [4] Swell sharks have also been known to look for food in lobster traps. [2]

Defense

When the shark feels threatened, it will bend its body into a U–shape, grab its tail fin with its mouth, and suck in water. [2] Doing so causes the shark to enlarge in diameter and makes it much harder for predators to bite or dislodge. [2] [4] The swell shark is capable of swelling by using water or air, which is stored in the stomach until released. [2] [4] When letting air out, the swell shark makes a dog-like bark. [2] [5] Swell sharks are non-aggressive and are considered harmless to humans. [3] [2] [5]

Biofluorescence of the swell shark Cephaloscyllium ventriosum biofluorescence.jpg
Biofluorescence of the swell shark

Biofluorescence

8-Bromo-kynurenine yellow, a fluorescent pigment found in the skin of the swell shark 8-Bromo-kynurenine yellow.png
8-Bromo-kynurenine yellow, a fluorescent pigment found in the skin of the swell shark

Swell shark biofluorescence was first reported in 2014. Researchers presented species-specific emission patterns, indicating that biofluorescence potentially functions in intraspecific communication and assists camouflage. [7] The key fluorecent pigments in the swell shark and the chain catshark are a set of brominated kynurenine compounds that appear to be synthesized by the kynurenine pathway starting from 6-bromo-tryptophan. [6] The biochemical origin of 6-bromo-tryptophan in these species is not known.

Conservation status

Swell shark touch tank at the Central Coast Aquarium in Avila Beach, California. Cephaloscyllium ventriosum Central Coast Aquarium.jpg
Swell shark touch tank at the Central Coast Aquarium in Avila Beach, California.

There are no fishery operations that target swell sharks, however, they are occasionally caught as bycatch in lobster and crab traps, gillnets, and trawls. [2] Swell sharks are not typically consumed by humans due to the poor quality of meat. [1] [2] [5] Swell sharks are common in public aquariums, in part due to their longevity in captivity. [2] [4] The IUCN has assessed the swell shark as "least concern". [1]

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

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

The redspotted catshark, also known as the Chilean catshark, is a species of catshark commonly found in the coastal waters of the southeastern Pacific, from central Peru to southern Chile. They are typically found in the rocky sublittoral areas at the edge of the continental shelf, in waters down to 100 m in depth. They spend the spring, summer, and fall in rocky subtidal areas, but winter in deeper offshore waters due to the strong currents at that time of year.

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

The horn shark is a species of bullhead shark, in the family Heterodontidae. It is endemic to the coastal waters off the western coast of North America, from California to the Gulf of California. Young sharks are segregated spatially from the adults, with the former preferring deeper sandy flats and the latter preferring shallower rocky reefs or algal beds. A small species typically measuring 1 m (3.3 ft) in length, the horn shark can be recognized by a short, blunt head with ridges over its eyes, two high dorsal fins with large spines, and a brown or gray coloration with many small dark spots.

<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">Australian swellshark</span> Species of shark

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<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">Pyjama shark</span> Species of shark

The pyjama shark or striped catshark is a species of catshark, and part of the family Scyliorhinidae, endemic to the coastal waters of South Africa. This abundant, bottom-dwelling species can be found from the intertidal zone to a depth of around 100 m (330 ft), particularly over rocky reefs and kelp beds. With a series of thick, parallel, dark stripes running along its stout body, the pyjama shark has an unmistakable appearance. It is additionally characterized by a short head and snout with a pair of slender barbels that do not reach the mouth, and two dorsal fins that are placed far back on the body. It can grow up to a length of 1.1 m (3.6 ft) long.

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

The leopard catshark is a species of catshark, and part of the family Scyliorhinidae, endemic to the coastal waters of South Africa. Abundant in inshore waters under 20 m (66 ft) deep, this bottom-dweller favors rocky reefs, kelp beds, and sandy flats. Growing to a length of 84 cm (33 in), the leopard catshark has a stout body with two dorsal fins placed well back, and a short head and tail. It is extremely variable in color and pattern, with individuals ranging from almost white to black and covered by diverse patterns of black spots, blotches, rosettes, and/or lines. The color pattern changes with age and some forms seem to be location-specific, suggesting the presence of multiple distinct, local populations. In the past, some of the more distinct color forms have been described as different species.

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The tiger catshark is a species of catshark, belonging to the family Scyliorhinidae. 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">Cloudy catshark</span> Species of shark

The cloudy catshark 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.

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The peppered catshark is a common but little-known species of catshark, part of the family Scyliorhinidae, inhabiting depths of 130–1,326 m (427–4,350 ft) in the northern Gulf of California. It is found on or near the ocean floor, and conducts seasonal migrations, spending winter in deeper water. Reaching a length of 37 cm (15 in), this species has a slender grayish body with a fine covering of black dots. On the dorsal edge of its caudal fin is a prominent crest of enlarged dermal denticles. It is oviparous, with the reproductive period probably lasting from May to September. The International Union for Conservation of Nature (IUCN) has listed the peppered catshark under Least Concern, as it faces no significant threats from human activity.

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.

The saddled swellshark is a rare species of catshark, and part of the family Scyliorhinidae, endemic to Eastern Australia. This bottom-dwelling species is found on the outer continental shelf and upper continental slope at a depth of 115–605 m (377–1,985 ft). It is a robustly built shark with a short, broad, flattened head and a capacious mouth. Adults are patterned with saddles on a brownish or grayish background, which varies between tropical and temperate sharks; juveniles are light-colored with many spots. This shark reaches 74 cm (29 in) in length. Like other swellsharks, it can inflate itself as a defensive measure. Reproduction is oviparous.

The Cook's swellshark is a little-known species of catshark, belonging to the family Scyliorhinidae. This shark is found in the Arafura Sea at a depth of 223–300 m (732–984 ft). It is a stocky-bodied shark with a short, broad head and a large mouth, and can be identified by the eight dark, pale-edged saddles along its grayish brown body and tail. The maximum known length of this species is 30 cm (12 in). Like other swellsharks, it can inflate itself with water or air when threatened.

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

The Australian reticulate swellshark is a little-known species of catshark in the family Scyliorhinidae. It is found off the coast of northwestern Australia at depths of 290–420 m (950–1,380 ft). This shark has a stocky body and a short, wide head with a capacious mouth. It is characterized by a striking dorsal color pattern of dark brown lines that trace a series of hollow saddles and narrow rings, on a light background. Like other swellsharks, this species can inflate itself when threatened. Its reproduction is oviparous.

The flagtail swellshark is a little-known species of catshark, belonging to the family Scyliorhinidae, found at a depth of 480–700 m (1,570–2,300 ft) off northeastern Queensland, and possibly also nearby islands. This stout-bodied shark has a short, broad, and flattened head with a capacious mouth. Adults have a variegated brown coloration with 9–10 darker dorsal saddles and V-shaped blotch at the tip of the upper caudal fin lobe. Juveniles are yellow with narrow brown bars instead of saddles, and a distinctive marking between the spiracles shaped like two loops connected by a line. Like other swellsharks, this species can inflate its body when threatened.

References

  1. 1 2 3 4 5 6 7 Villavicencio-Garayzar, C.J.; White, C.F.; Lowe, C.G (2015). "Cephaloscyllium ventriosum". IUCN Red List of Threatened Species . 2015: e.T60227A80671800. doi: 10.2305/IUCN.UK.2015-4.RLTS.T60227A80671800.en . Retrieved 11 November 2021.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 "swell shark". Florida Museum of Natural History. Retrieved 2009-06-14.
  3. 1 2 3 4 5 6 7 8 "Cephaloscyllium ventriosum". FishBase . Retrieved 2009-07-07.
  4. 1 2 3 4 5 6 7 8 "Kelp Forest: Swell Shark". Elasmo-Research. Retrieved 2009-07-07.
  5. 1 2 3 4 5 6 7 8 "Swell Shark". www.aquariumofpacific.org. Retrieved 2018-06-22.
  6. 1 2 Park, Hyun Bong; Lam, Yick Chong; Gaffney, Jean P.; Weaver, James C.; Krivoshik, Sara Rose; Hamchand, Randy; Pieribone, Vincent; Gruber, David F.; Crawford, Jason M. (2019). "Bright Green Biofluorescence in Sharks Derives from Bromo-Kynurenine Metabolism". iScience. 19: 1291–1336. Bibcode:2019iSci...19.1291P. doi: 10.1016/j.isci.2019.07.019 . PMC   6831821 . PMID   31402257.
  7. ↑ Sparks, John S.; Schelly, Robert C.; Smith, W. Leo; Davis, Matthew P.; Tchernov, Dan; Pieribone, Vincent A.; Gruber, David F. (2014). "The Covert World of Fish Biofluorescence: A Phylogenetically Widespread and Phenotypically Variable Phenomenon". PLOS ONE. 9 (1): e83259. Bibcode:2014PLoSO...983259S. doi: 10.1371/journal.pone.0083259 . PMC   3885428 . PMID   24421880.
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