Goblin shark
Overview
 
The goblin shark, Mitsukurina owstoni, is a deep-sea shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....

, the sole living species in the family Mitsukurinidae
Mitsukurinidae
Mitsukurinidae, also called goblin sharks is a family of sharks with one living genus, Mitsukurina, and three extinct genera: Anomotodon, Pseudoscapanorhynchus and Scapanorhynchus, though some taxonomists consider Scapanorhynchus to be a synonym of Mitsukurina...

. The most distinctive characteristic of the goblin shark is the unusual shape of its head. It has a long, trowel
Trowel
A trowel is one of several similar hand tools used for digging, smoothing, or otherwise moving around small amounts of viscous or particulate material.-Hand tools:...

-shaped, beak-like rostrum
Rostrum (anatomy)
The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....

 or snout, much longer than other sharks' snouts. Some other distinguishing characteristics of the shark are the color of its body, which is mostly pink, and its long, protrusible jaws.
Encyclopedia
The goblin shark, Mitsukurina owstoni, is a deep-sea shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....

, the sole living species in the family Mitsukurinidae
Mitsukurinidae
Mitsukurinidae, also called goblin sharks is a family of sharks with one living genus, Mitsukurina, and three extinct genera: Anomotodon, Pseudoscapanorhynchus and Scapanorhynchus, though some taxonomists consider Scapanorhynchus to be a synonym of Mitsukurina...

. The most distinctive characteristic of the goblin shark is the unusual shape of its head. It has a long, trowel
Trowel
A trowel is one of several similar hand tools used for digging, smoothing, or otherwise moving around small amounts of viscous or particulate material.-Hand tools:...

-shaped, beak-like rostrum
Rostrum (anatomy)
The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....

 or snout, much longer than other sharks' snouts. Some other distinguishing characteristics of the shark are the color of its body, which is mostly pink, and its long, protrusible jaws. When the jaws are retracted, the shark resembles a pink grey nurse shark
Grey nurse shark
The sand tiger shark or grey nurse shark is a species of shark that inhabits coastal waters worldwide. It lives very close to the shorelines and beaches of North America, hence the name, sand tiger shark. Despite a fearsome appearance and strong swimming abilities, it is a relatively placid and...

, Carcharias taurus, with an unusually long nose.

Mitsukurina owstoni is found in the deep ocean, far below where the sun's light can reach at depths greater than 200 m. They can be found throughout the world, from Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 in the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

 to the Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...

 in the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

. They are best known from the waters around Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, where the species was first discovered.

Goblin sharks feed on a variety of organisms that live in deep waters. Among some of their known prey are deep-sea squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...

, crabs and deep-sea fish. Very little is known about the species' life history and reproductive habits, as encounters with them have been relatively rare. As seemingly rare as they are however, there seems to be no real threat to their populations and so they are not classified as endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

 by the IUCN.

Distribution and habitat

Mitsukurina owstoni is a bathydemersal deep-water shark usually found near the sea bottom, at depths of around 250 m. The deepest specimen ever caught was found at 1,300 m.

There are only about 45 known specimens of Mitsukurina owstoni.

Most goblin sharks that have been caught were from Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

 (where it was first discovered), specifically in an area between Tosa Bay and Boso Peninsula
Boso Peninsula
thumb|Locationthumb|Landsat image with high-resolution data from Space Shuttle is a peninsula in Chiba prefecture on Honshū, the largest island of Japan. It forms the eastern edge of Tokyo Bay, separating it from the Pacific Ocean....

. The species' Pacific range is rather large. M. owstoni specimens have been found in the waters off South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

, from various sites throughout the western Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

. Goblin sharks have also been found off the coasts of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 and New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

.

In the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

, they have been found in the western Atlantic off French Guiana
French Guiana
French Guiana is an overseas region of France, consisting of a single overseas department located on the northern Atlantic coast of South America. It has borders with two nations, Brazil to the east and south, and Suriname to the west...

, in the eastern Atlantic in the Bay of Biscay
Bay of Biscay
The Bay of Biscay is a gulf of the northeast Atlantic Ocean located south of the Celtic Sea. It lies along the western coast of France from Brest south to the Spanish border, and the northern coast of Spain west to Cape Ortegal, and is named in English after the province of Biscay, in the Spanish...

 and off Madeira
Madeira
Madeira is a Portuguese archipelago that lies between and , just under 400 km north of Tenerife, Canary Islands, in the north Atlantic Ocean and an outermost region of the European Union...

 and continental Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...

. On the other side of the Atlantic, goblin sharks have been found in the Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...

.

Anatomy and appearance

Goblin sharks can grow to 11 feet (3.3 m) long and weigh 350 lb (159 kg). They have the typical shark's semi-fusiform body. Unlike the common image of sharks, M. owstonis fins are not pointed and instead are low and rounded, with the anal and pelvic fins significantly larger than the dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

s. Their heterocercal tails are similar to the thresher shark
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 three species all within the genus Alopias.-Taxonomy:...

's, with the upper lobe significantly longer proportionately than other sharks'. In addition, the goblin shark's tail lacks a ventral lobe.

The pink coloration, unique among sharks, is due to blood vessels underneath a semi-transparent skin (which bruises easily), thereby causing the coloring. The fins have a bluish appearance. Goblin sharks lack a nictitating membrane
Nictitating membrane
The nictitating membrane is a transparent or translucent third eyelid present in some animals that can be drawn across the eye for protection and to moisten it while maintaining visibility. Some reptiles, birds, and sharks have a full nictitating membrane; in many mammals, there is a small...

. They have no precaudal pit and no keels. The front teeth are long and smooth-edged, while the rear teeth are adapted for crushing.

Up to 25% of the goblin shark's body weight can be its liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...

. This is similar to other sharks, such as the basking shark
Basking shark
The basking shark is the second largest living fish, after the whale shark. It is a cosmopolitan migratory species, found in all the world's temperate oceans. It is a slow moving and generally harmless filter feeder and has anatomical adaptations to filter feeding, such as a greatly enlarged...

 and the frilled shark, and contributes to the buoyancy
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...

 of the shark, which, like all sharks, lacks a swim bladder.

Behaviour

Goblin sharks hunt by sensing the presence of prey with electro-sensitive organs in the rostrum
Rostrum (anatomy)
The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....

, or snout, due to the absence of light in the deep waters where it swims. Once a shark finds its prey, it suddenly protrudes its jaws, while using a tongue-like muscle to suck the victim into its sharp front teeth. They have been known to feed on deep-sea rockfish (Helicolenus dactylopterus was found in one specimen), cephalopods and crustaceans.

Reproduction

Next to nothing is known of the goblin shark's reproductive habits. Even though a pregnant goblin shark has never been caught or found, as members of the order Lamniformes
Lamniformes
Lamniformes is an order of sharks commonly known as mackerel sharks . It includes some of the most familiar species of sharks, such as the great white shark, as well as more unusual representatives, such as the goblin shark and the megamouth shark.Members of the order are distinguished by...

, they are assumed to be ovoviviparous; their eggs mature and hatch inside the mother's body and the shark gives birth to live young.

Importance to humans

Goblin sharks are most often encountered as fisheries' bycatch
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...

. As they stay near the sea bottom, they are usually caught via deep bottom-set gillnets and sea-bottom long line fishing
Long-line fishing
Longline fishing is a commercial fishing technique. It uses a long line, called the main line, with baited hooks attached at intervals by means of branch lines called "snoods". A snood is a short length of line, attached to the main line using a clip or swivel, with the hook at the other end....

. They are also sometimes caught by trawling
Trawling
Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net that is used for trawling is called a trawl....

. In addition, they are sometimes found entangled by deep-sea fishing lines.

There is a demand by some collectors for the skeletal jaws of goblin sharks. Prices of these jaws range from US$1,500 to US$4,000.

Specific occurrences

The first goblin shark discovered was caught by a Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

ese fisherman in the Kuroshio Current
Kuroshio Current
The Kuroshio is a north-flowing ocean current on the west side of the North Pacific Ocean. It is similar to the Gulf Stream in the North Atlantic and is part of the North Pacific ocean gyre...

 off the coast of Yokohama, Japan in 1897. This specimen was later identified as a 3.5-ft male shark.

In 1985, a goblin shark was discovered in waters off eastern Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. Several specimens have been caught in the vicinity of New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

 and Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...

 and are preserved at the Australian Museum
Australian Museum
The Australian Museum is the oldest museum in Australia, with an international reputation in the fields of natural history and anthropology. It features collections of vertebrate and invertebrate zoology, as well as mineralogy, palaeontology, and anthropology...

. A four-meter long specimen was caught in waters off Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...

 in 2004. The shark was taken to the national fish collection in Hobart
Hobart
Hobart is the state capital and most populous city of the Australian island state of Tasmania. Founded in 1804 as a penal colony,Hobart is Australia's second oldest capital city after Sydney. In 2009, the city had a greater area population of approximately 212,019. A resident of Hobart is known as...

. In nearby New Zealand, a goblin shark was also caught in 1988.

In 2003, more than a hundred goblin sharks were caught off the northwest coast of Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...

, an area in which they have previously not been found. Reportedly, the sharks were caught a short time after an earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...

 occurred in the area.

A goblin shark was kept by the Tokai University
Tokai University
is a private university in Tokyo, Japan. It was established in 1943 by Shigeyoshi Matsumae, who had formerly been the engineering president of the Ministry of Communications...

 of Japan; the specimen died after a week.

On January 25, 2007 a 1.3 m long goblin shark was caught alive in Tokyo Bay, in waters 150 to 200 m (500 to 650 ft) deep. It was taken to the Tokyo Sea Life Park to be displayed in an aquarium, but died two days later on January 27.

Later the same year in April, several goblin sharks were seen swimming in shallow waters in the Japanese Sea. A live one was caught near Tokyo Bay. It is the first time goblin sharks have been seen swimming in shallow waters.

In August 2008, a live Goblin Shark was filmed in the wild in Japan by NHK (a short clip was broadcast as part of NHK Tokushuu on 31 August). During the shooting, the small (1.3 meter) goblin shark was shown biting into the wetsuit of a human diver's forearm - however, this scene was staged in order to demonstrate the shark's jaw movements, and goblin sharks basically present no threat to human divers under normal circumstances.

Role in the ecosystem

The goblin shark is an upper-level carnivore
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...

 in its natural habitat. As a macro-organism, it has its fair share of external and internal parasites
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...

. Two new species of tapeworm were discovered in a specimen captured off Australia, Litobothrium amsichensis
Litobothrium amsichensis
Litobothrium amsichensis is a tapeworm from the family Litobothridae.This species was first described from a specimen collected from the spiral valve digestive organ of a goblin shark caught in New South Wales in Australia....

 and Marsupiobothrium gobelinus
Marsupiobothrium gobelinus
Marsupiobothrium gobelinus is a tapeworm with an unknown taxonomic affinity.It can easily be distinguished from the other members of its family by its bothridial peduncles, longer in comparison to other family members. Its lacks arcuate cylindrical pads on the posterior bothridial margins...

.

Conservation status

In 2004, Mitsukurina owstoni was classified by the IUCN's Shark Red List Authority as a species of "Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...

". The rationale given was that despite the fact that goblin shark sightings have been relatively rare, the worldwide distribution of the species, combined with the fact that it was not accidentally taken often as bycatch
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...

 in fisheries, ensured that the species is most probably not in any reasonable danger of extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

. The IUCN described the major threats to M. owstoni populations' as either harvesting (as an intentional target for fishing), accidental mortality (bycatch) and to a lesser extent, water pollution
Water pollution
Water pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....

. There are no active conservation efforts being made toward this specific species.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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