Thresher shark

Thresher sharks are large lamniform sharks of the family Alopiidae found in all temperate and tropical oceans of the world; the family contains four species, all within the genus Alopias.

Thresher shark
Temporal range: 49–0 Ma[1]
Lutetian to Recent
Thresher
Pelagic thresher (A. pelagicus)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Lamniformes
Family: Alopiidae
Bonaparte, 1838
Genus: Alopias
Rafinesque, 1810
Type species
Alopias macrourus
Rafinesque, 1810
Synonyms
  • Alopecias Müller and Henle, 1837
  • Alopius Swainson, 1838
  • Vulpecula Jarocki, 1822

Taxonomy

The genus and family name derive from the Greek word alopex, meaning fox. As a result, the long-tailed or common thresher shark, Alopias vulpinus, is also known as the fox shark.[2] The common name is derived from a distinctive, thresher-like tail or caudal fin which can be as long as the body of the shark itself.

Species

The three extant thresher shark species are all in the genus Alopias. The possible existence of a hitherto unrecognized fourth species was revealed during the course of a 1995 allozyme analysis by Blaise Eitner. This species is apparently found in the eastern Pacific off Baja California, and has previously been misidentified as the bigeye thresher. So far, it is only known from muscle samples from one specimen, and no aspect of its morphology has been documented.[3]

Phylogeny and evolution

Megachasmidae

voidAlopiidaevoid

A. vulpinus

undescribed Alopias sp.

A. superciliosus

A. pelagicus

Cetorhinidae

Lamnidae

Phylogeny of Alopiidae[3][4]

Based on cytochrome b genes, Martin and Naylor (1997) concluded the thresher sharks form a monophyletic sister group to the clade containing the families Cetorhinidae (basking shark) and Lamnidae (mackerel sharks). The megamouth shark (Megachasma pelagios) was placed as the next-closest relative to these taxa, though the phylogenetic position of that species has yet to be resolved with confidence. Cladistic analyses by Compagno (1991) based on morphological characters, and Shimada (2005) based on dentition, have both corroborated this interpretation.[4][5]

Within the family, an analysis of allozyme variation by Eitner (1995) found the common thresher is the most basal member, with a sister relationship to a group containing the unrecognized fourth Alopias species and a clade comprising the bigeye and pelagic threshers. However, the position of the undescribed fourth species was only based on a single synapomorphy (derived group-defining character) in one specimen, so some uncertainty in its placement remains.[3]

Distribution and habitat

Although occasionally sighted in shallow, inshore waters, thresher sharks are primarily pelagic; they prefer the open ocean, venturing no deeper than 500 metres (1,600 ft). Common threshers tend to be more common in coastal waters over continental shelves. Common thresher sharks are found along the continental shelves of North America and Asia of the North Pacific, but are rare in the Central and Western Pacific. In the warmer waters of the Central and Western Pacific, bigeye and pelagic thresher sharks are more common. A thresher shark was seen on the live video feed from one of the ROVs monitoring BP's Macondo oil well blowout in the Gulf of Mexico. This is significantly deeper than the 500m previously thought to be their limit. A bigeye has also turned up in the western Mediterranean and so distribution may be wider than previously believed or environmental factors may be forcing sharks to search for new territories [1]

Anatomy and appearance

Pacifica thresher shark
Small purple colored thresher caught at Pacifica Pier, California

Named for their exceptionally long, thresher-like heterocercal tail or caudal fins (which can be as long as the total body length), thresher sharks are active predators; the tail is used as a weapon to stun prey. The thresher shark has a short head and a cone-shaped nose. The mouth is generally small, and the teeth range in size from small to large.[6] By far the largest of the three species is the common thresher, Alopias vulpinus, which may reach a length of 6.1 metres (20 ft) and a weight of over 500 kilograms (1,100 lb). The bigeye thresher, Alopias superciliosus, is next in size, reaching a length of 4.9 m (16 ft); at just 3 m (10 ft), the pelagic thresher, Alopias pelagicus, is the smallest.

Thresher sharks are fairly slender, with small dorsal fins and large, recurved pectoral fins. With the exception of the bigeye thresher, these sharks have relatively small eyes positioned to the forward of the head. Coloration ranges from brownish, bluish or purplish gray dorsally with lighter shades ventrally.[7] The three species can be roughly distinguished by the main color of the dorsal surface of the body. Common threshers are dark green, bigeye threshers are brown and pelagic threshers are generally blue. Lighting conditions and water clarity can affect how any one shark appears to an observer, but the color test is generally supported when other features are examined.

Diet

Pelagic schooling fish (such as bluefish, juvenile tuna, and mackerel), squid and cuttlefish are the primary food items of the thresher sharks. They are known to follow large schools of fish into shallow waters. Crustaceans and occasionally seabirds are also taken.

Behavior

External video
Stunning tail: Thresher sharks evolved to slap and kill their preyNBC News

Thresher sharks are solitary creatures which keep to themselves. It is known that thresher populations of the Indian Ocean are separated by depth and space according to sex. Some species however do occasionally hunt in a group of two or three contrary to their solitary nature. All species are noted for their highly migratory or oceanodromous habits. When hunting schooling fish, thresher sharks are known to "slap" the water, herding and stunning prey.[7] The elongated tail is used to swat smaller fish, stunning them before feeding.[8] Thresher sharks are one of the few shark species known to jump fully out of the water, making turns like dolphins; this behavior is called breaching.

Endothermy

Two species of the thresher have been identified as having a modified circulatory system that acts as a counter-current heat exchanger, which allows them to retain metabolic heat. Mackerel sharks (family Lamnidae) have a similar homologous structure to this which is more extensively developed. This structure is a strip of red muscle along each of its flanks, which has a tight network of blood vessels that transfer metabolic heat inward towards the core of the shark, allowing it to maintain and regulate its body heat.

Reproduction

No distinct breeding season is observed by thresher sharks. Fertilization and embryonic development occur internally; this ovoviviparous or live-bearing mode of reproduction results in a small litter (usually two to four) of large well-developed pups, up to 150 cm at birth in thintail threshers. The young fish exhaust their yolk sacs while still inside the mother, at which time they begin feasting on the mother's unfertilized eggs; this is known as oophagy.

Thresher sharks are slow to mature; males reach sexual maturity between seven and 13 years of age and females between eight and 14 years in bigeye threshers. They may live for 20 years or more. In October 2013, the very first picture of a Thresher shark giving birth was taken by Attila Kaszo off the coast of the Philippines.[9]

Importance to humans

Threshers have a low fecundity, like all large sharks, and are highly vulnerable to overfishing. Besides being hunted for their meat, threshers are also hunted for their liver oil, skin (for leather), and their fins, for use in shark-fin soup.

They do not appear to be a threat to humans, although some divers have been hit with the upper tail lobe. A dubious account of a fisherman being decapitated by a tail swipe as the shark breached has been reported.[10]

Thresher sharks are classified as prized game fish in the United States and South Africa. Common thresher sharks are the target of a popular recreational fishery off Baja, Mexico. Thresher sharks are hunted in some areas for their value as both a recreational sport fish and for commercial products derived from their flesh.

Conservation

All three thresher shark species have been listed as vulnerable to extinction by the World Conservation Union since 2007 (IUCN).[11]

See also

References

  • "Alopias". Integrated Taxonomic Information System. Retrieved 4 May 2006.
  • Froese, Rainer, and Daniel Pauly, eds. (2011). Species of Alopias in FishBase. February 2011 version.
  1. ^ Bourdon, J. (April 2009). Fossil Genera: Alopias. The Life and Times of Long Dead Sharks. Retrieved on October 6, 2009.
  2. ^ "fox shark - shark species". Encyclopædia Britannica.
  3. ^ a b c Eitner, B. (1995). "Systematics of the Genus Alopias (Lamniformes: Alopiidae) with Evidence for the Existence of an Unrecognized Species". Copeia. American Society of Ichthyologists and Herpetologists. 1995 (3): 562–571. doi:10.2307/1446753. JSTOR 1446753.
  4. ^ a b Sims, D.W., ed. (2008). Advances in Marine Biology, Volume 54. Academic Press. p. 175. ISBN 0-12-374351-6.
  5. ^ Shimada, K. (2005). "Phylogeny of lamniform sharks (Chondrichthyes: Elasmobranchii) and the contribution of dental characters to lamniform systematics". Paleontological Research. 9 (1): 55–72. doi:10.2517/prpsj.9.55.
  6. ^ "Family Alopiidae: Thresher Sharks – 3 species". ReefQuest Centre for Shark Research. Retrieved 2011-10-17.
  7. ^ a b "Thresher Shark".
  8. ^ Oliver SP, Turner JR, Gann K, Silvosa M and D'Urban Jackson T (2013) "Thresher sharks use tail-slaps as a hunting strategy" PLoS ONE, 8 (7): e67380. doi:10.1371/journal.pone.0067380
  9. ^ "Rare shark birth photographed for the first time". www.msn.com. Retrieved 7 April 2018.
  10. ^ Dawkins, Richard (2004). The Ancestor's Tale. New York: Houghton Mifflin. ISBN 0-618-00583-8.
  11. ^ "More oceanic sharks added to the IUCN Red List" (Press release). IUCN. 2007-02-22. Retrieved 2015-03-11.

External links

Alopias grandis

Alopias grandis is a species of giant thresher shark from the Neogene. Estimates calculated from teeth comparisons suggest the living animal was up to 15 metres (49 ft) long, making it one of the largest sharks (Megalodon being the largest). Remains generally consist of teeth, which have been found in the United States in Beaufort County, South Carolina.

Bigeye thresher

The bigeye thresher (Alopias superciliosus) is a species of thresher shark, family Alopiidae, found in temperate and tropical oceans worldwide. Like other thresher sharks, nearly half its total length consists of the elongated upper lobe of the tail fin. Its common name comes from its enormous eyes, which are placed in keyhole-shaped sockets that allow them to be rotated upward. This species can also be distinguished by a pair of deep grooves on the top of its head, from which its scientific name is derived.

The large eyes of the bigeye thresher are adapted for hunting in low light conditions. It is one of the few sharks that conduct a diel vertical migration, staying in deep water during the day and moving into surface waters at night to feed. To protect its sensitive brain and eyes from the temperature changes accompanying these movements, the bigeye thresher has a vascular exchange system called the rete mirabile around those organs. This species feeds mainly on fish and squid, which are stunned via whip-like strikes of the long tail. Bigeye threshers are ovoviviparous, usually bearing litters of two pups. The embryos are oophagous and feed on ova produced by the mother while inside the uterus. This shark is caught by commercial fisheries across its range; the meat is not highly regarded but the skin, fins, and liver oil are valued. It has been assessed as Vulnerable by the International Union for Conservation of Nature (IUCN).

Cardiff Market

Cardiff Market (Welsh: Marchnad Caerdydd), also known as Cardiff Central Market (Welsh: Marchnad Ganolog Caerdydd) and as the Market Building, is a Victorian indoor market in the Castle Quarter of Cardiff city centre, capital city of Wales.

Common thresher

The common thresher (Alopias vulpinus), also known by many names such as Atlantic thresher, big-eye thresher, fox shark, green thresher, swingletail, slasher, swiveltail, thintail thresher, whip-tailed shark and Zorro thresher shark, is the largest species of thresher shark, family Alopiidae, reaching some 6 m (20 ft) in length. About half of its length consists of the elongated upper lobe of its caudal fin. With a streamlined body, short pointed snout, and modestly sized eyes, the common thresher resembles (and has often been confused with) the pelagic thresher (A. pelagicus). It can be distinguished from the latter species by the white of its belly extending in a band over the bases of its pectoral fins. The common thresher is distributed worldwide in tropical and temperate waters, though it prefers cooler temperatures. It can be found both close to shore and in the open ocean, from the surface to a depth of 550 m (1,800 ft). It is seasonally migratory and spends summers at lower latitudes.

The long tail of the common thresher, the source of many fanciful tales through history, is used in a whip-like fashion to deliver incapacitating blows to its prey. This species feeds mainly on small schooling forage fishes such as herrings and anchovies. It is a fast, strong swimmer that has been known to leap clear of the water, and possesses physiological adaptations that allow it to maintain an internal body temperature warmer than that of the surrounding sea water. The common thresher has an aplacental viviparous mode of reproduction, with oophagous embryos that feed on undeveloped eggs ovulated by their mother. Females typically give birth to four pups at a time, following a gestation period of nine months.

Despite its size, the common thresher is minimally dangerous to humans due to its relatively small teeth and timid disposition. It is highly valued by commercial fishers for its meat, fins, hide, and liver oil; large numbers are taken by longline and gillnet fisheries throughout its range. This shark is also esteemed by recreational anglers for the exceptional fight it offers on hook-and-line. The common thresher has a low rate of reproduction and cannot withstand heavy fishing pressure for long, a case in point being the rapid collapse of the thresher shark fishery off California in the 1980s. With commercial exploitation increasing in many parts of the world, the International Union for Conservation of Nature has assessed this species as vulnerable.

Daanbantayan

Daanbantayan, officially the Municipality of Daanbantayan, (Cebuano: Lungsod sa Daanbantayan; Tagalog: Bayan ng Daanbantayan), is a 1st class municipality in the province of Cebu, Philippines. According to the 2015 census, it has a population of 84,430 people.Located at the northern tip of Cebu island, Daanbantayan celebrates its annual fiesta along with the Haladaya Festival which starts 21 August and ends with street-dancing on 30 August, in honor of Datu Daya, the legendary founder of the town.

Daanbantayan is bordered on the north by the Visayan Sea, to the west by Bantayan Island, on the east by the Camotes Sea, and on the south by the town of Medellin.

Index of fishing articles

This page is a list of fishing topics.

King-of-the-salmon

King-of-the-salmon, Trachipterus altivelis, is a species of ribbonfish in the family Trachipteridae. Its common name comes from the legends of the Makah people west of the Strait of Juan de Fuca, which hold that this fish leads the salmon annually to their spawning grounds. Catching or eating king-of-the-salmon was forbidden, as it was feared killing one would stop the salmon run. This myth is reflected by a former specific epithet used for this fish, rex-salmonorum, rex being Latin for "king". The king-of-the-salmon is found in the eastern Pacific Ocean from Alaska to Chile. It is usually found in the open ocean to a depth of 900 meters (3,000 feet), though adults sometimes feed on the sea bottom.

This species attains a known length of 1.83 meters (6.0 feet), though larger specimens have been reported. It has an elongated, ribbon-shaped body with a long dorsal fin running along its entire length. The dorsal fin is highest in the front and contains 165–184 soft rays. The pectoral fins are small and rounded, the pelvic fins are greatly reduced, and the anal fin is absent. The dorsal lobe of the caudal fin, containing 7–8 rays, points upward at a 45° angle to the body axis, while the ventral lobe is reduced to 5–6 spines. The eyes are large and the mouth is small but highly protrusible. The fish is silver with crimson-colored fins; the area above the eye is blackish.Reproduction is oviparous, with pelagic eggs and larvae. Spawning appears to take place year-round with no specific peak. In the Northern Hemisphere, the density of the eggs is greatest towards the southern extents of its range, suggesting a relationship between spawning and warmer water temperatures. The eggs measure 2.6–3.7 mm (0.10–0.15 in) in diameter. The juveniles have longer fins than the adults, especially the first 5 rays of the dorsal fin and the pelvic fins, which are elongated with rows of pigmented swellings. Juvenile coloration is silvery with red fins and 3–5 dark blotches on the sides above the lateral line.

Large king-of-the-salmon feed on copepods, krill, small pelagic fishes, young rockfishes, squid, and octopus, while small individuals feed on copepods, polychaete worms, and fish larvae. Off the coast of Oregon, juveniles have different diets depending on habitat. Offshore juveniles feed mainly on the hyperiid amphipod Phronima, also taking small numbers of other amphipods, copepods, and free-floating fish scales. Inshore juveniles feed mainly on copepods and fish larvae. Known predators of small king-of-the-salmon include the bigeye thresher shark (Alopias superciliosus) and the longnose lancetfish (Alepisaurus ferox). This species is occasionally encountered while trolling for salmon, in nets, or washed up on the shore.

List of cartilaginous fish of Sri Lanka

Sri Lanka is a tropical island situated close to the southern tip of India. The diversity of fish fauna within the inland waterways and around the island is very high considering the small size of the island.

List of common fish names

This is a list of common fish names. While some common names refer to a single species or family, others have been used for a confusing variety of types; the articles listed here should explain the possibilities if the name is ambiguous.

List of sharks

Sharks belong to the superorder Selachimorpha in the subclass Elasmobranchii, in the class Chondrichthyes. The Elasmobranchii also include rays and skates; the Chondrichthyes also include Chimaeras. The first sharks appeared in the oceans over 440 million years ago.

Listed below are extant species of shark. Sharks are spread across 512 described and 23 undescribed species in eight orders. The families and genera within the orders are listed in alphabetical order. Also included is a field guide to place sharks into the correct order.

Malapascua

Malapascua is a Philippine island situated in the Visayan Sea, 6.8 kilometres (4.2 mi) across a shallow strait from the northernmost tip of Cebu Island. Administratively, it is part of the peninsular barangay of Logon, Daanbantayan, Cebu. Malapascua is a small island, only about 2.5 by 1 kilometre (1.55 by 0.62 mi), and has eight hamlets.

Memorandum of Understanding on the Conservation of Migratory Sharks

The Memorandum of Understanding on the Conservation of Migratory Sharks is an international instrument for the conservation of migratory species of sharks. It was founded under the auspices of the Convention on the Conservation of Migratory Species of Wild Animals (CMS; also known as the Bonn Convention).

Pelagic thresher

The pelagic thresher (Alopias pelagicus) is a species of thresher shark, family Alopiidae; this group of sharks is characterized by the greatly elongated upper lobes of their caudal fins. The pelagic thresher occurs in the tropical and subtropical waters of the Indian and Pacific Oceans, usually far from shore, but occasionally entering coastal habitats. It is often confused with the common thresher (A. vulpinus), even in professional publications, but can be distinguished by the dark, rather than white, color over the bases of its pectoral fins. The smallest of the three thresher species, the pelagic thresher typically measures 3 m (10 ft) long.

The diet of the pelagic thresher consists mainly of small midwater fishes, which are stunned with whip-like strikes of its tail. Along with all other mackerel sharks, the pelagic thresher exhibits ovoviviparity and usually gives birth to litters of two. The developing embryos are oophagous, feeding on unfertilized eggs produced by the mother. The young are born unusually large, up to 43% the length of the mother. Pelagic threshers are valued by commercial fisheries for their meat, skin, liver oil, and fins, and are also pursued by sport fishers. The International Union for Conservation of Nature assessed this species as vulnerable in 2007.

Shark

Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii) and are the sister group to the rays. However, the term "shark" has also been used for extinct members of the subclass Elasmobranchii outside the Selachimorpha, such as Cladoselache and Xenacanthus, as well as other Chondrichthyes such as the holocephalid eugenedontidans.

Under this broader definition, the earliest known sharks date back to more than 420 million years ago. Acanthodians are often referred to as "spiny sharks"; though they are not part of Chondrichthyes proper, they are a paraphyletic assemblage leading to cartilaginous fish as a whole. Since then, sharks have diversified into over 500 species. They range in size from the small dwarf lanternshark (Etmopterus perryi), a deep sea species of only 17 centimetres (6.7 in) in length, to the whale shark (Rhincodon typus), the largest fish in the world, which reaches approximately 12 metres (40 ft) in length. Sharks are found in all seas and are common to depths of 2,000 metres (6,600 ft). They generally do not live in freshwater although there are a few known exceptions, such as the bull shark and the river shark, which can be found in both seawater and freshwater. Sharks have a covering of dermal denticles that protects their skin from damage and parasites in addition to improving their fluid dynamics. They have numerous sets of replaceable teeth.Well-known species such as the great white shark, tiger shark, blue shark, mako shark, thresher shark, and hammerhead shark are apex predators—organisms at the top of their underwater food chain. Many shark populations are threatened by human activities.

Shark meat

Shark meat is a seafood consisting of the flesh of sharks. Its consumption by humans has been mentioned since fourth century AD literature. Several sharks are fished for human consumption, such as porbeagles, shortfin mako shark, requiem shark, and thresher shark, among others. Shark meat is popular in Asia, where it is often consumed dried, smoked, or salted. Shark meat is consumed regularly in Scandinavia, Japan, parts of India, parts of Canada, Sri Lanka, areas of Africa and Mexico. In western cultures, shark meat is sometimes considered as a taboo, although its popularity has increased in Western countries.

Thresher

Thresher may refer to:

Threshing machine (or thresher), a device that first separates the head of a stalk of grain from the straw, and then further separates the kernel from the rest of the head:Pedal powered thresher, a low-tech threshing machine that is operated using pedals.Thresher shark, a type of shark with a distinctly scythe-shaped tail

USS Thresher refers to two United States Navy submarines, named after the Thresher shark:USS Thresher (SS-200), a Tambor-class submarine that served in World War II

USS Thresher (SSN-593), the lead ship of her class of nuclear-powered attack submarines and was lost by accident on 10 April 1963Threshers (First Quench Retailing), a UK off licence chain

Rice Thresher, the undergraduate student newspaper of Rice University

Clearwater Threshers, a minor league baseball team in the Florida State League

USS Sea Fox (SS-402)

USS Sea Fox (SS-402), a Balao-class submarine, was a vessel of the United States Navy named for the sea fox, a large shark, also called the thresher shark, which frequents the coast of Europe and the Americas.

Sea Fox was laid down on 2 November 1943 at the Portsmouth Navy Yard in Kittery, Maine; launched on 28 March 1944, sponsored by Mrs. Robert N. Robertson, widow of Lieutenant Robert N. Robertson, who survived the sinking of USS Squalus only to be lost during the war as executive officer of USS Argonaut. The submarine was commissioned on 13 June 1944, Lieutenant Commander Roy C. Klinker in command.

USS Thresher (SSN-593)

The second USS Thresher (SSN-593) was the lead boat of her class of nuclear-powered attack submarines in the United States Navy. She was the U.S. Navy's second submarine to be named after the thresher shark.

On 10 April 1963, Thresher sank during deep-diving tests about 220 miles (350 km) east of Boston, Massachusetts, killing all 129 crew and shipyard personnel aboard in the deadliest submarine disaster ever. Her loss was a watershed for the U.S. Navy, leading to the implementation of a rigorous submarine safety program known as SUBSAFE. The first nuclear submarine lost at sea, Thresher was also the first of only two submarines that killed more than 100 people aboard; the other was the Russian Kursk, which sank with 118 aboard in 2000.

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.