Bowmouth guitarfish
Encyclopedia
The bowmouth guitarfish, mud skate, or shark ray (Rhina ancylostoma, sometimes misgendered
Grammatical gender
Grammatical gender is defined linguistically as a system of classes of nouns which trigger specific types of inflections in associated words, such as adjectives, verbs and others. For a system of noun classes to be a gender system, every noun must belong to one of the classes and there should be...

 ancylostomus) is a species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of ray
Batoidea
Batoidea is a superorder of cartilaginous fish commonly known as rays and skates, containing more than 500 described species in thirteen families...

 related to guitarfish
Guitarfish
The guitarfish are a family, Rhinobatidae, of rays. The guitarfish are known for an elongated body with a flattened head and trunk and small ray like wings. The combined range of the various species is tropical, subtropical and temperate waters worldwide. They often travel in large...

es and skate
Skate
Skates are cartilaginous fish belonging to the family Rajidae in the superorder Batoidea of rays. There are more than 200 described species in 27 genera. There are two subfamilies, Rajinae and Arhynchobatinae ....

s, and the sole member of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Rhinidae. It is found widely in the tropical coastal waters of the Indo-Pacific
Indo-Pacific
The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...

 region, at depths of up to 90 m (295.3 ft). Highly distinctive in appearance, the bowmouth guitarfish has a wide, thick body with a blunt snout and large, shark-like dorsal
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...

 and tail fins. The line of its mouth is strongly undulating, and there are multiple thorny ridges over its head and back. It has dorsal color pattern of many white spots over a bluish gray to brown background, with a pair of prominent markings over the pectoral fins. This large species can grow to 2.7 m (8.9 ft) long and 135 kg (297.6 lb).

Strong-swimming and demersal in nature, the bowmouth guitarfish prefers sandy or muddy flats and areas adjacent to reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....

s, where it hunts for crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s, molluscs, and bony fishes. Reproduction is aplacental viviparous, with recorded litter sizes ranging from 4 to 9. The International Union for Conservation of Nature (IUCN) has assessed this species as Vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...

; its sizable pectoral fins are greatly valued as food and it is widely caught by artisanal
Artisan fishing
Artisan fishing is a term used to describe small scale low-technology commercial or subsistence fishing practices. The term particularly applies to coastal or island ethnic groups using traditional techniques such as rod and tackle, arrows and harpoons, throw nets and drag nets, and traditional...

 and commercial fisheries
Commercial fishing
Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often pursue fish far into the ocean under adverse conditions...

. Its thorns and propensity for damaging netted catches, however, cause it to be viewed as a nuisance by trawlers. Habitat destruction
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...

 and degradation likely pose an additional, significant challenge to this species' survival. The bowmouth guitarfish adapts relatively well to captivity and is displayed in some public aquarium
Public aquarium
A public aquarium is the aquatic counterpart of a zoo, housing living aquatic species for viewing. Most public aquariums feature tanks larger than those kept by home aquarists, as well as smaller tanks. Since the first public aquariums were built in the mid-19th century, they have become popular...

s.

Taxonomy and phylogeny

German naturalist
Naturalist
Naturalist may refer to:* Practitioner of natural history* Conservationist* Advocate of naturalism * Naturalist , autobiography-See also:* The American Naturalist, periodical* Naturalism...

s Marcus Elieser Bloch
Marcus Elieser Bloch
Marcus Elieser Bloch was a German medical doctor and naturalist. He is generally considered one of the most important ichthyologists of the 18th century.- Life :...

 and Johann Gottlob Schneider
Johann Gottlob Schneider
Johann Gottlob Theaenus Schneider was a German classicist and naturalist.-Biography:Schneider was born at Collm in Saxony...

 originally described the bowmouth guitarfish in their 1801 Systema Ichthyologiae, based on a 51 cm (20.1 in) long specimen collected from off the Coromandel Coast
Coromandel Coast
The Coromandel Coast is the name given to the southeastern coast of the Indian Subcontinent between Cape Comorin and False Divi Point...

 of India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, which has since been lost. In his 1990 phylogenetic study, Kiyonori Nishida concluded that Rhina and Rhynchobatus
Rhynchobatus
Rhynchobatus is a group of rays commonly known as wedgefishes, and the sole genus in the family Rhynchobatidae. They are found in the tropical and subtropical Indo-Pacific with a single species in the eastern Atlantic...

are the sister clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

 to all other batoids except for the sawfish
Sawfish
Sawfish, also known as the Carpenter Shark, are a family of rays, characterized by a long, toothy nose extension snout. Several species can grow to approximately . The family as a whole is largely unknown and little studied...

es. John McEachran and Neil Aschliman (2004) found that, based on morphological
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....

 characters, Rhina is the most basal member of the Rajiformes. Systematists have variously classified the bowmouth guitarfish with the family Rhinobatidae (which was polyphyletic prior to recent revisions), Rhynchobatidae, or in its own family; the last was the arrangement recognized by Joseph Nelson in Fishes of the World
Fishes of the World
Fishes of the World by Joseph S. Nelson is a standard reference for fish systematics. Now in its fourth edition, the work is a comprehensive overview of the 25,000-plus species known to science....

(4th edition, 2006), as it has phylogenetic support.

Distribution and habitat

Widely distributed in the tropical Indian
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 and Pacific Oceans, the bowmouth guitarfish is found from KwaZulu-Natal
KwaZulu-Natal
KwaZulu-Natal is a province of South Africa. Prior to 1994, the territory now known as KwaZulu-Natal was made up of the province of Natal and the homeland of KwaZulu....

 in 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...

 northward to the Red Sea
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...

, including the Seychelles
Seychelles
Seychelles , officially the Republic of Seychelles , is an island country spanning an archipelago of 115 islands in the Indian Ocean, some east of mainland Africa, northeast of the island of Madagascar....

. From there, its range extends eastward through the Indian subcontinent
Indian subcontinent
The Indian subcontinent, also Indian Subcontinent, Indo-Pak Subcontinent or South Asian Subcontinent is a region of the Asian continent on the Indian tectonic plate from the Hindu Kush or Hindu Koh, Himalayas and including the Kuen Lun and Karakoram ranges, forming a land mass which extends...

 and Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...

, including the Maldives
Maldives
The Maldives , , officially Republic of Maldives , also referred to as the Maldive Islands, is an island nation in the Indian Ocean formed by a double chain of twenty-six atolls oriented north-south off India's Lakshadweep islands, between Minicoy Island and...

, to as far north as southern 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...

 and Korea
Korea
Korea ) is an East Asian geographic region that is currently divided into two separate sovereign states — North Korea and South Korea. Located on the Korean Peninsula, Korea is bordered by the People's Republic of China to the northwest, Russia to the northeast, and is separated from Japan to the...

, and as far east as Papua New Guinea
Papua New Guinea
Papua New Guinea , officially the Independent State of Papua New Guinea, is a country in Oceania, occupying the eastern half of the island of New Guinea and numerous offshore islands...

 and northern 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...

, where it occurs from Shark Bay
Shark Bay
Shark Bay is a World Heritage listed bay in Western Australia. The term may also refer to:* the locality of Shark Bay, now known as Denham* Shark Bay Marine Park* Shark Bay , a shark exhibit at Sea World, Gold Coast, Australia* Shire of Shark Bay...

 in Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...

 to Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...

 in 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...

.

The bowmouth guitarfish inhabits coastal waters over a depth range of 3–90 m (9.8–295.3 ft). It is typically encountered on or near the bottom, though on occasion it may be seen swimming well above it. This species favors sandy or muddy habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...

s, and can also be found in the vicinity of rocky and coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...

s and shipwreck
Shipwreck
A shipwreck is what remains of a ship that has wrecked, either sunk or beached. Whatever the cause, a sunken ship or a wrecked ship is a physical example of the event: this explains why the two concepts are often overlapping in English....

s.

Description

The bowmouth guitarfish is large and heavily built, measuring up to 2.7 m (8.9 ft) in length and weighing 135 kg (297.6 lb). The head is short, wide, and depressed, with a broadly rounded snout; the anterior portion of the head, including the eyes and large spiracle
Spiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...

s, is clearly distinct from the body. The nostril
Nostril
A nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation...

s are elongated and oriented nearly crosswise, with well-developed flaps of skin that separate each opening into inflow and outflow apertures. The lower jaw has three protruding lobes that fit into three depressions in the upper jaw. There are around 47 upper tooth rows and 50 lower tooth rows; the teeth are ridged and arranged in winding bands. The five pairs of gill slit
Gill slit
Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of Cartilaginous fish such as sharks, rays, sawfish, and guitarfish. Most of these have five pairs, but a few species have 6 or 7 pairs...

s are positioned underneath, close to the lateral margins of the head.

The body is deepest in front of the two 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, which are tall and falcate (sickle-shaped). The first dorsal fin is about a third larger than the second and originates over the pelvic fin origins, whereas the second dorsal is located midway between the first dorsal and the caudal fin. The pectoral fins are broad and triangular, with a deep indentation between their origins and the sides of the head. The pelvic fins are much smaller than the pectoral fins, and the anal fin is absent. The tail is much longer than the body, with a large, crescent-shaped caudal fin; the lower caudal fin lobe is more than half the length of the upper.

There is a thick ridge running along the midline of the back, bearing a band of massive, sharp thorns. More thorn-bearing ridges are found in front of the eyes, from over the eyes to behind the spiracles, and on the "shoulders". The entire dorsal surface has a granular texture from a dense covering of dermal denticles. The coloration is bluish gray above, lightening towards the margins of the head and pectoral fins, and light gray to white below. There are prominent white spots scattered over the body and fins, a white-edged black marking above each pectoral fin, and two dark transverse bands atop the head between the eyes. Younger individuals are more vividly colored than adults, which tend to be more brownish with a fainter pattern and proportionately smaller spots.

Biology and ecology

The bowmouth guitarfish is an active species with a shark-like swimming style. It is most active at night, and is not known to be territorial. This species has crushing dentition and feeds mainly on bottom-dwelling crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s, such as crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...

s and shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...

, though molluscs and bony fishes are also consumed. The bowmouth guitarfish is known to fall prey to the tiger shark
Tiger shark
The tiger sharks, Galeocerdo cuvier, is a species of requiem shark and the only member of the genus Galeocerdo. Commonly known as sea tigers, tiger sharks are relatively large macropredators, capable of attaining a length of over . It is found in many tropical and temperate waters, and is...

 (Galeocerdo cuvier). The thorns on its head and back are employed in defense (including butting). Parasites that have been documented from this species include the tapeworm Tylocephalum carnpanulatum, the trematode Melogonimus rhodanometra, the monogenea
Monogenea
Monogenea are a group of largely ectoparasitic members of the flatworm phylum Platyhelminthes, class Monogenea.-Characteristics:Monogenea are very small parasitic flatworms mainly found on skin or gills of fish....

ns Branchotenthes robinoverstreeti and Monocotyle ancylostomae, and the copepod
Copepod
Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...

 Nesippus vespa. There is a record of an individual being serviced by bluestreak cleaner wrasse
Bluestreak cleaner wrasse
The bluestreak cleaner wrasse is one of several species of cleaner wrasse found on coral reefs in the Indian Ocean and much of the Pacific Ocean, as well as many seas, including the Red Sea and those around Southeast Asia...

s (Labroides dimidiatus). This species is aplacental viviparous, with the developing embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...

s being sustained by yolk. Michael (1993) reported the litter size as 4 and the birth size as 45 cm (17.7 in), while Last and Stevens (2009) noted a female specimen pregnant with 9 mid-term embryos, measuring 27–31 cm (10.6–12.2 in) long. Males attain sexual maturity
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...

 at 1.5–1.8 m (4.9–5.9 ft) long.

Human interactions

Throughout its range, the bowmouth guitarfish is captured intentionally and incidentally by artisanal
Artisan fishing
Artisan fishing is a term used to describe small scale low-technology commercial or subsistence fishing practices. The term particularly applies to coastal or island ethnic groups using traditional techniques such as rod and tackle, arrows and harpoons, throw nets and drag nets, and traditional...

 and commercial fisheries
Commercial fishing
Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often pursue fish far into the ocean under adverse conditions...

, using trawls, gillnet
Gillnet
Gillnetting is a common fishing method used by commercial and artisanal fishermen of all the oceans and in some freshwater and estuary areas. The gillnet also is used by fisheries scientists to monitor fish populations. Because gillnets can be so effective their use is closely monitored and...

s, and line gear. The pectoral fins are exceedingly valuable and usually the only part brought to market, though the meat is sometimes also sold fresh or dried and salted in Asia for human consumption. Larger bowmouth guitarfish are considered a nuisance by trawl fishers, as their rough skin and thorns make them difficult to handle and may damage the rest of the catch. In Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...

, the enlarged thorns of this species are used to make bracelet
Bracelet
A bracelet is an article of jewelry which is worn around the wrist. Bracelets can be manufactured from metal, leather, cloth, plastic or other materials and sometimes contain jewels, rocks, wood, and/or shells...

s.

The International Union for Conservation of Nature (IUCN) has assessed the bowmouth guitarfish as Vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...

; it is threatened by fishing and habitat destruction
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...

 and degradation, particularly from blast fishing
Blast fishing
Blast fishing or dynamite fishing is the practice of using explosives to stun or kill schools of fish for easy collection. This often illegal practice can be extremely destructive to the surrounding ecosystem, as the explosion often destroys the underlying habitat that supports the fish...

, coral bleaching
Coral bleaching
Coral bleaching is the loss of intracellular endosymbionts through either expulsion or loss of algal pigmentation.The corals that form the structure of the great reef ecosystems of tropical seas depend upon a symbiotic relationship with unicellular flagellate protozoa, called zooxanthellae, that...

, and siltation
Siltation
Siltation is the pollution of water by fine particulate terrestrial clastic material, with a particle size dominated by silt or clay. It refers both to the increased concentration of suspended sediments, and to the increased accumulation of fine sediments on bottoms where they are undesirable...

. Its numbers are known to have declined in Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

n waters, where it is targeted by guitarfish
Guitarfish
The guitarfish are a family, Rhinobatidae, of rays. The guitarfish are known for an elongated body with a flattened head and trunk and small ray like wings. The combined range of the various species is tropical, subtropical and temperate waters worldwide. They often travel in large...

 gillnet fisheries. The bowmouth guitarfish has been assessed as Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...

 off Australia, where it is not a targeted species but is taken 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...

. The installation of turtle excluder device
Turtle excluder device
A turtle excluder device or TED is a specialized device that allows a captured sea turtle to escape when caught in a fisherman's net.In particular, sea turtles can be caught when bottom trawling is used by the commercial shrimp fishing industry. In order to catch shrimp, a fine meshed trawl net is...

s (TEDs) on some Australian trawlers has benefited this species. The bowmouth guitarfish is a popular subject of public aquarium
Public aquarium
A public aquarium is the aquatic counterpart of a zoo, housing living aquatic species for viewing. Most public aquariums feature tanks larger than those kept by home aquarists, as well as smaller tanks. Since the first public aquariums were built in the mid-19th century, they have become popular...

s and fares relatively well, with one individual having lived for 7 years in captivity. Rare and facing many conservation threats, it has been called "the panda
Panda
Panda or Panda bear most often refers to:*Giant panda, an animal in the Bear familyPanda may also refer to:*Red panda, the only living member in the Ailuridae family-In biology:* Species related to the Giant panda...

 of the aquatic world". In 2007, the Newport Aquarium
Newport Aquarium
-External links:*...

 initiated the world's first captive breeding
Captive breeding
Captive breedingis the process of breeding animals in human controlled environments with restricted settings, such as wildlife reserves, zoos and other conservation facilities; sometimes the process is construed to include release of individual organisms to the wild, when there is sufficient...

program for this species.
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