Swellshark

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Swell shark
Swell Shark, San Clemente Island, California.jpg
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Carcharhiniformes
Family: Scyliorhinidae
Genus: Cephaloscyllium
Species:C. ventriosum
Binomial name
Cephaloscyllium ventriosum
(Garman, 1880)
Cephaloscyllium ventriosum distmap.png
Range of the swellshark (in blue)

The swellshark (Cephaloscyllium ventriosum) is a catshark of the family Scyliorhinidae. It is found in the subtropical eastern Pacific Ocean between latitudes 40° N and 37° S, from the surface to 460 m.

Catshark family of fishes

Catsharks are ground sharks of the family Scyliorhinidae. They are one of the largest families of sharks with around 160 species placed in 17 genera. Although they are generally known as catsharks, many species are commonly called dogfish or gato. Like most bottom feeders, they feed on benthic invertebrates and smaller fish. Catsharks are not harmful to humans.

Family is one of the eight major hierarcical taxonomic ranks in Linnaean taxonomy; it is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks between the ranks of family and genus. The official family names are Latin in origin; however, popular names are often used: for example, walnut trees and hickory trees belong to the family Juglandaceae, but that family is commonly referred to as being the "walnut family".

Pacific Ocean Ocean between Asia and Australia in the west, the Americas in the east and Antarctica or the Southern Ocean in the south.

The Pacific Ocean is the largest and deepest of Earth's oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean in the south and is bounded by Asia and Australia in the west and the Americas in the east.

Contents

It grows to about 100 centimeters (39 in) [2] in length, and can expand its body to about double its regular size to prevent its predators such as seals and larger sharks from pulling it out from rocky reefs, under ledges, and in crevices. [2] The swellshark's appearance resembles that of the leopard shark in that it has spots. Younger swellsharks are lighter in color than the older ones. Swellsharks are nocturnal, sleeping in reef crevices and caves during the day. Sometimes, these sharks will grab onto their tail with their mouth in a ring shape to prevent other fish from being able to attack them. During the night they hunt molluscs, crustaceans and bony fish. The swellshark is oviparous, and the females lay two flattened egg sacks which contain the embryo which is attached by two tendrils to a reef. Swellsharks are commonly found in aquariums and are completely harmless to humans, usually staying completely motionless when encountered by divers. The World Conservation Union has assessed this species as a least concern species worldwide, as it is usually not fished by divers and fishermen due to its poor flesh quality. However the occasional swellshark is killed by fishermen and this along with its low egg production may put the species at risk.

Pinniped Infraorder of mammals

Pinnipeds, commonly known as seals, are a widely distributed and diverse clade of carnivorous, fin-footed, semiaquatic marine mammals. They comprise the extant families Odobenidae, Otariidae, and Phocidae. There are 33 extant species of pinnipeds, and more than 50 extinct species have been described from fossils. While seals were historically thought to have descended from two ancestral lines, molecular evidence supports them as a monophyletic lineage. Pinnipeds belong to the order Carnivora and their closest living relatives are bears and musteloids, having diverged about 50 million years ago.

Leopard shark species of shark (Triakis semifasciata)

The leopard shark is a species of houndshark, in the family Triakidae. It is found along the Pacific coast of North America, from the U.S. state of Oregon to Mazatlán in Mexico. Typically measuring 1.2–1.5 m (3.9–4.9 ft) long, this slender-bodied shark is immediately identifiable by the striking pattern of black saddle-like markings and large spots over its back, from which it derives its common name. Large schools of leopard sharks are a common sight in bays and estuaries, swimming over sandy or muddy flats or rock-strewn areas near kelp beds and reefs. They are most common near the coast, in water less than 4 m (13 ft) deep.

Mollusca Large phylum of invertebrate animals

Mollusca is the second largest phylum of invertebrate animals. The members are known as molluscs or mollusks. Around 85,000 extant species of molluscs are recognized. The number of fossil species is estimated between 60,000 and 100,000 additional species.

Taxonomy

When discovered in 1880, the swellshark was first described as Scyllium ventriosum, but was later changed to Cephaloscyllium ventriosum. [3] The Greek word kephale which means "head" and skylla which is the name of a mythological creature was used for the term Cephaloscyllium, while ventriosum, Latin for "large belly" was used to describe the shark's ability to suck in water. [3]

Greek language language spoken in Greece, Cyprus and Southern Albania

Greek is an independent branch of the Indo-European family of languages, native to Greece, Cyprus and other parts of the Eastern Mediterranean and the Black Sea. It has the longest documented history of any living Indo-European language, spanning more than 3000 years of written records. Its writing system has been the Greek alphabet for the major part of its history; other systems, such as Linear B and the Cypriot syllabary, were used previously. The alphabet arose from the Phoenician script and was in turn the basis of the Latin, Cyrillic, Armenian, Coptic, Gothic, and many other writing systems.

Distribution and habitat

The swellshark can be found in the Eastern Pacific, the central California coast, the Gulf of California, and the southern tip of Mexico. [2] Swellsharks have been reported as far south as Chile, but that is believed to be a different species. [2] It can be found over continental shelves and subtropical waters and can be seen as deep as 457 m (1,499 ft) or as close as five meters below the surface. [3] Swellsharks are often found over algae-covered rock bottoms. [3] In the California area, it shares the same habitat as the horn shark and unlike that shark, the swellshark is more tolerant of water temperatures below 20 °C (70 °F). [4]

California State of the United States of America

California is a state in the Pacific Region of the United States. With 39.6 million residents, California is the most populous U.S. state and the third-largest by area. The state capital is Sacramento. The Greater Los Angeles Area and the San Francisco Bay Area are the nation's second and fifth most populous urban regions, with 18.7 million and 8.8 million residents respectively. Los Angeles is California's most populous city, and the country's second most populous, after New York City. California also has the nation's most populous county, Los Angeles County, and its largest county by area, San Bernardino County. The City and County of San Francisco is both the country's second-most densely populated major city after New York and the fifth-most densely populated county, behind only four of the five New York City boroughs.

Gulf of California A gulf of the Pacific Ocean between the Baja peninsula and the Mexican mainland

The Gulf of California is a marginal sea of the Pacific Ocean that separates the Baja California Peninsula from the Mexican mainland. It is bordered by the states of Baja California, Baja California Sur, Sonora, and Sinaloa with a coastline of approximately 4,000 km (2,500 mi). Rivers which flow into the Gulf of California include the Colorado, Fuerte, Mayo, Sinaloa, Sonora, and the Yaqui. The gulf's surface area is about 160,000 km2 (62,000 sq mi). Depth soundings in the gulf have ranged from fording depth at the estuary near Yuma, Arizona, to in excess of 3,000 meters (9,800 ft) in the deepest parts.

Mexico country in the southern portion of North America

Mexico, officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatemala, Belize, and the Caribbean Sea; and to the east by the Gulf of Mexico. Covering almost 2,000,000 square kilometres (770,000 sq mi), the nation is the fifth largest country in the Americas by total area and the 13th largest independent state in the world. With an estimated population of over 120 million people, the country is the eleventh most populous state and the most populous Spanish-speaking state in the world, while being the second most populous nation in Latin America after Brazil. Mexico is a federation comprising 31 states and Mexico City, a special federal entity that is also the capital city and its most populous city. Other metropolises in the state include Guadalajara, Monterrey, Puebla, Toluca, Tijuana and León.

Anatomy and appearance

Swellsharks have a rounded dorsal fin located in the pelvic area. [2] Another fin is located in the anal area. [2] The fins are light brown with dark patches and are covered along with the rest of its body with black dots. [2] Usually the younger sharks are lighter in color than the adults. [3] Its spotted coloration closely resembles that of the leopard shark. [3] The gills of a swellshark are usually very small and tight. [3] Swellshark eyes are large and gold and the lower eyelid is nictitating. [2] [3] The largest swellsharks can be up to 110 centimeters (43 in) but are usually around 90 centimeters (35 in) in length. [2] [3] Every swellshark has around 55–60 teeth, which contains mostly small teeth. [3] When threatened, it can swell up to double its regular size. [2]

Pelvis lower part of the trunk of the human body between the abdomen and the thighs (sometimes also called pelvic region of the trunk

The pelvis is either the lower part of the trunk of the human body between the abdomen and the thighs or the skeleton embedded in it.

Biology and ecology

Diet and behavior

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

When hunting at night, the swellshark hunts for bony fish, molluscs, and crustaceans [2] by lying on the bottom of the ocean, and waiting until its prey is a few centimeters away before it attacks. [3] [5] Another hunting tactic used by the swellshark is to lie on the bottom of the ocean with its mouth open, waiting for a fish to swim into its mouth. [5] Swellsharks also enter lobster traps to get an easy meal. [3] Swellsharks are nocturnal and sleep in reef crevices during the day. 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. [3] Doing so makes it more difficult for predators to remove it from rocky crevices, allows the shark to double in size, and makes it harder for larger sharks and seals to eat it. [3] [6] During the time when the air is in its stomach, the swellshark floats upward to the water surface. [7] When letting the air out, the swellshark makes a dog–like bark. [3] This fish is very sociable with other sharks, and is commonly seen sleeping next to or on top of one another. [5] [8]

Lobster trap portable trap used in lobster fishing

A lobster trap or lobster pot is a portable trap that traps lobsters or crayfish and is used in lobster fishing. In Scotland, the word creel is used to refer to a device used to catch lobsters and other crustaceans. A lobster trap can hold several lobsters. Lobster traps can be constructed of wire and wood, or metal and netting or rigid plastic. An opening permits the lobster to enter a tunnel of netting or other one-way device. Pots are sometimes constructed in two parts, called the "chamber" or "kitchen", where there is bait, and exits into the "parlour", where it is trapped from escape. Lobster pots are usually dropped to the sea floor about a dozen at a time, and are marked by a buoy so they can be picked up later.

Coral reef Outcrop of rock in the sea formed by the growth and deposit of stony coral skeletons

A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups.

Biofluorescence of the swellshark Cephaloscyllium ventriosum biofluorescence.jpg
Biofluorescence of the swellshark

Biofluorescence

The swellshark was reported to be biofluorescent in 2014, that is, when illuminated by blue or ultraviolet light, it re-emits it as green, and appears differently than under white light illumination. Researchers presented species-specific emission patterns, indicating that biofluorescence potentially functions in intraspecific communication and assists camouflage. [9]

Reproduction

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

The swellshark is oviparous and they lay two green or amber [8] flattened eggs which are attached to the reef with tendrils. [2] It has been suggested that the length of the tendrils depends on the amount of surf action the region is under. [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). [3] The embryos will feed solely on yolk before they hatch. [8] The hatching time for swellshark eggs solely depends on water temperature but usually will hatch between 7.5–12 months. [3] [8] When born after this period of time in the egg, [10] the swellshark pup will immediately begin feeding on molluscs and crustaceans. [3]

Related Research Articles

Egg case (Chondrichthyes) natural collagen casing found encompassing some aquatic lifeforms fertilized eggs

An egg case or egg capsule is the casing that surrounds the eggs of oviparous sharks, skates, and chimaeras. Egg cases typically contain one embryo, except for big skate and mottled skate egg cases, which contain up to 7 embryos. Oviparity is completely absent in the superorder Squalomorphii.

Chain catshark species of fish

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.

Horn shark species of shark (Heterodontus francisci)

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 fishes

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.

Tawny nurse shark Nebrius ferrugineus

The tawny nurse shark is a species of carpet shark in the family Ginglymostomatidae, and the only extant member of the genus Nebrius.

Barbeled houndshark species of shark (Leptocharias smithii)

The barbeled houndshark is a species of ground shark and the only member of the family Leptochariidae. This demersal species is found in the coastal waters of the eastern Atlantic Ocean from Mauritania to Angola, at depths of 10–75 m (33–246 ft). It favors muddy habitats, particularly around river mouths. The barbeled houndshark is characterized by a very slender body, nasal barbels, long furrows at the corners of the mouth, and sexually dimorphic teeth. Its maximum known length is 82 cm (32 in).

Draughtsboard shark species of fish

The draughtsboard shark is a species of catshark, and part of the family Scyliorhinidae, so named for its "checkerboard" color 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.

Australian swellshark species of fish

The Australian swellshark or draughtboard shark is a species of catshark, and part of the family Scyliorhinidae, endemic to southern Australia. This bottom-dwelling species can be found on the continental shelf down to a depth of 220 m (720 ft). Usually measuring 1 m (3 ft) long, it is a stout-bodied, broad-headed shark with a short tail and a first dorsal fin much larger than the second. It can be identified by its variegated dorsal coloration of brown or gray patches and numerous spots.

Blotchy swellshark species of fish

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.

Pyjama shark species of shark (Poroderma africanum)

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.

Sharptooth houndshark species of shark (Triakis megalopterus)

The sharptooth houndshark, or spotted gully shark is a species of houndshark in the family Triakidae found in shallow inshore waters from southern Angola to South Africa. Favoring sandy areas near rocky reefs and gullies, it is an active-swimming species that usually stays close to the bottom. This robust shark reaches 1.7 m (5.6 ft) in length and has characteristically large, rounded fins; the pectoral fins in particular are broad and sickle-shaped in adults. It also has a short, blunt snout and long furrows around its mouth. This species is gray or bronze in color above, with variable amounts of black spotting.

Dark shyshark species of fish

The dark shyshark or pretty Happy is a species of catshark, belonging to the family Scyliorhinidae, endemic to the temperate waters off southern Namibia and western South Africa. It is benthic in nature and inhabits shallow, inshore waters and favors rocky reefs and kelp forests. Growing to 60 cm (24 in) long, this small, stocky shark has a wide, flattened head with a rounded snout and a large flap of skin extending from before the nostrils to the mouth. Its dorsal coloration is extremely variable and may feature black-edged orange to blackish saddles and/or white spots on a light brown to nearly black background.

Tiger catshark species of fish

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.

Cloudy catshark species of fish

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.

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.

Australian reticulate swellshark species of fish

The Australian reticulate swellshark is a little-known species of catshark, belonging to 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 painted swellshark is a little-known species of catshark, belonging to the family Scyliorhinidae, found in eastern Indonesia. This species reaches a maximum known length of 72 cm (28 in), and has a thick body with a short, broad and flattened head. It is dark gray with a variegated pattern of irregular darker and lighter blotches above, and lighter below with gray blotches and speckling on the snout. Like other swellsharks, it can inflate itself as a defensive measure.

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

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  2. 1 2 3 4 5 6 7 8 9 10 11 12 "California Swell Shark". Elasmodiver.com. Retrieved 2009-06-14.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 "Swellshark". Florida Museum of Natural History . Retrieved 2009-06-14.
  4. Ebert, D.A. (2003). Sharks, Rays, and Chimaeras of California. University of California Press. pp. 8186. ISBN   0-520-23484-7.
  5. 1 2 3 4 "Kelp Forest: Swell Shark". Elasmo-Research. Retrieved 2009-07-07.
  6. Baldwin, Tiye (October 11, 2002). "Touch Tanks To Move to New Facility". University of California, Santa Barbara. Retrieved 2009-06-20.
  7. "Bullhead Shark is Small". St. Petersburg Times . November 10, 1940. Retrieved 2009-06-20.
  8. 1 2 3 4 "Cephaloscyllium ventriosum". FishBase . Retrieved 2009-07-07.
  9. 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. doi:10.1371/journal.pone.0083259. PMC   3885428 Lock-green.svg. PMID   24421880.
  10. O'Connor, John (January 13, 1982). "TV: 'Sharks' and 'All Things' on PBS". New York Times . Retrieved 2009-06-20.