''Rhina ancylostoma'', the bowmouth guitarfish, shark ray or mud skate, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

ray Ray may refer to: Fish * Ray (fish), any cartilaginous fish of the superorder Batoidea * Ray (fish fin anatomy), a bony or horny spine on a fin Science and mathematics * Ray (geometry), half of a line proceeding from an initial point * Ray (g ...

and a member of the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Rhinidae Wedgefishes are rays of the family Rhinidae, comprising eleven species in three genera. Classified in the order Rhinopristiformes along with guitarfishes and sawfishes, they have also been known as giant guitarfishes or sharkfin guitarfishes. T ...

. Its evolutionary affinities are not fully resolved, though it may be related to true guitarfishes and

skate Skate or Skates may refer to: Fish *Skate (fish), several genera of fish belonging to the family Rajidae * Pygmy skates, several genera of fish belonging to the family Gurgesiellidae * Smooth skates or leg skates, several genera of fish belongin ...

s. This rare species occurs widely in the

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

coastal waters of the western

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

, at depths of up to . Highly distinctive in appearance, ''Rhina ancylostoma'' has a wide and thick body with a rounded snout and large shark-like

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...

and tail fins. Its mouth forms a W-shaped undulating line, and there are multiple thorny ridges over its head and back. It has a dorsal color pattern of many white spots over a bluish gray to brown background, with a pair of prominent black markings over the

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

s. This large species can reach a length of and weight of . Usually found near the

sea floor The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...

, ''Rhina ancylostoma'' prefers sandy or muddy areas near underwater structures. It is a strong-swimming

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

bony fish Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartilag ...

es,

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

s, and

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

s. This species gives live birth to litters of two to eleven pups, which are nourished during

gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregna ...

yolk Among animals which produce eggs, the yolk (; also known as the vitellus) is the nutrient-bearing portion of the egg whose primary function is to supply food for the development of the embryo. Some types of egg contain no yolk, for example bec ...

. The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

(IUCN) has assessed ''Rhina ancylostoma'' as Vulnerable because it is widely caught by

artisanal An artisan (from french: artisan, it, artigiano) is a skilled craft worker who makes or creates material objects partly or entirely by hand. These objects may be functional or strictly decorative, for example furniture, decorative art, s ...

and

commercial fisheries 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 ...

for its valuable fins and meat. It is viewed as a nuisance by

trawl Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net used for trawling is called a trawl. This principle requires netting bags which are towed through water to catch different speci ...

ers, however, because its bulk and thorny skin cause it to damage netted catches.

Habitat degradation Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

and

destruction Destruction may refer to: Concepts * Destruktion, a term from the philosophy of Martin Heidegger * Destructive narcissism, a pathological form of narcissism * Self-destructive behaviour, a widely used phrase that ''conceptualises'' certain kind ...

pose an additional, significant challenge to this ray's survival. ''Rhina ancylostoma'' adapts well to captivity and is displayed in

public aquarium A public aquarium (plural: ''public aquaria'' or ''public Water Zoo'') is the aquatic counterpart of a zoo, which houses living aquatic animal and plant specimens for public viewing. Most public aquariums feature tanks larger than those kept b ...

Taxonomy and phylogeny

German naturalists

Marcus Elieser Bloch Marcus Elieser Bloch (1723–1799) was a German physician and naturalist who is best known for his contribution to ichthyology through his multi-volume catalog of plates illustrating the fishes of the world. Brought up in a Hebrew-speaking Jewish ...

and

Johann Gottlob Schneider Johann Gottlob Theaenus Schneider (18 January 1750 – 12 January 1822) was a German Empire, German classicist and natural history, naturalist. Biography Schneider was born at Collm in Saxony. In 1774, on the recommendation of Christian Gottlob ...

described ''Rhina ancylostoma'' in their 1801 ''Systema Ichthyologiae''. Their account was based on a long

specimen Specimen may refer to: Science and technology * Sample (material), a limited quantity of something which is intended to be similar to and represent a larger amount * Biological specimen or biospecimen, an organic specimen held by a biorepository ...

, now lost, collected off the

Coromandel Coast The Coromandel Coast is the southeastern coastal region of the Indian subcontinent, bounded by the Utkal Plains to the north, the Bay of Bengal to the east, the Kaveri delta to the south, and the Eastern Ghats to the west, extending over an ...

of India. The genus name ''Rhina'' comes from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

''rhinos'' ("snout"); the

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

''ancylostoma'' is derived from the Greek ''ankylos'' ("curved" or "crooked") and ''stoma'' ("mouth"). Although Block and Schneider wrote the epithet as ''ancylostomus'' and that form appears in some literature, most modern sources regard the correct form to be ''ancylostoma''. Other

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

s for this species include shark ray, mud skate, shortnose mud skate, bow-mouthed angel fish, and bow-mouthed angel shark. The evolutionary relationships between ''Rhina ancylostoma'' and other rays are debated. Morphological evidence generally points to a close relationship between ''Rhina'', ''

Rhynchobatus ''Rhynchobatus'' is a group of rays commonly known as wedgefishes in the family Rhinidae. They are found in the tropical and subtropical Indo-Pacific with a single species (''R. luebberti'') in the eastern Atlantic. All species in this genus are ...

'' and '' Rhynchorhina'', which are a group of rays known as the wedgefishes that also have large, shark-like fins. Morphological analyses have tended to place these two genera basally among rays, though some have them as basal to just the

guitarfish The guitarfish, also referred to as shovelnose rays, 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 trop ...

es (Rhinobatidae) and

s (Rajidae) while others have them basal to all other rays except

sawfish Sawfish, also known as carpenter sharks, are a family of rays characterized by a long, narrow, flattened rostrum, or nose extension, lined with sharp transverse teeth, arranged in a way that resembles a saw. They are among the largest fish wi ...

es (Pristidae). A 2012 study based on

mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...

upheld ''Rhina'' and ''Rhynchobatus'' as

sister taxa In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

related to the guitarfishes, but also unexpectedly found that they formed a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

with the sawfishes rather than the skates. Following the description of ''Rhynchorhina'' in 2016, a study of mtDNA found that it is part of the same group and their phylogenetic relationship is ((''Rhynchobatus''+''Rhynchorhina'')+''Rhina''). In terms of classification, Bloch and Schneider originally placed the bowmouth guitarfish in the order Abdominales, a now-obsolete grouping of fishes defined by the positioning of their

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two en ...

s directly behind the

s. Modern sources have included it variously in the order

Rajiformes Rajiformes is one of the four orders in the superorder Batoidea, flattened cartilaginous fishes related to sharks. Rajiforms are distinguished by the presence of greatly enlarged pectoral fins, which reach as far forward as the sides of the head ...

, Rhinobatiformes, Rhiniformes, or the newly proposed Rhinopristiformes. The placement of the bowmouth guitarfish in the family

originates from the group "Rhinae", consisting of ''Rhina'' and ''Rhynchobatus'', in Johannes Müller and

Jakob Henle Friedrich Gustav Jakob Henle (; 9 July 1809 – 13 May 1885) was a German physician, pathologist, and anatomist. He is credited with the discovery of the loop of Henle in the kidney. His essay, "On Miasma and Contagia," was an early argument for ...

's 1841 ''Systematische Beschreibung der Plagiostomen''. Later authors have also assigned this species to the family Rhinobatidae or Rhynchobatidae. Joseph Nelson, in the 2006 fourth edition of ''

Fishes of the World ''Fishes of the World'' by the American ichthyologist Joseph S. Nelson (1937–2011) is a standard reference for fish systematics. Now in its fifth edition (2016), the work is a comprehensive overview of the diversity and classification of the ...

'', placed this species as the sole member of Rhinidae in the order Rajiformes, which is supported by morphological but not molecular data. More recent authorities have placed it in Rhinidae together with ''Rhynchobatus'' and ''Rhynchorhina'', reflecting both genetic data and the morphologically intermediate position of ''Rhynchobatus'' between ''Rhina'' and ''Rhynchorhina''.

Description

''Rhina ancylostoma'' is a heavily built fish growing to long and in weight. The head is short, wide, and flattened with an evenly rounded snout; the front portion of the head, including the medium-sized eyes and large

spiracle Spiracle or spiraculum may refer to: * Spiracle (arthropods), opening in the exoskeletons of some arthropods * Spiracle (vertebrates), openings on the surface of some vertebrates * Spiraculum, a genus of land snails in family Cyclophoridae Cycl ...

s, is clearly distinct from the body. The long nostrils are transversely oriented and have well-developed skin flaps on their anterior margins. The lower jaw has three protruding lobes that fit into corresponding depressions in the upper jaw. There are around 47 upper and 50 lower tooth rows arranged in winding bands; the teeth are low and blunt with ridges on the crown. The five pairs of ventral

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 and rays, as well as deep-branching vertebrates such as lampreys. In con ...

s are positioned close to the lateral margins of the head. The body is deepest in front of the two tall and falcate (sickle-shaped)

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

s. The first dorsal fin is about a third larger than the second and originates over the

origins. The second dorsal fin is located midway between the first dorsal and the

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

. The broad and triangular

s have a deep indentation where their leading margins meet the head. The

s are much smaller than the pectoral fins, and the

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

is absent. The tail is much longer than the body and ends in a large, crescent-shaped

; the lower caudal fin lobe is more than half the length of the upper. The entire dorsal surface has a grainy texture from a dense covering of tiny

dermal denticle A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as we ...

s. A thick ridge is present along the midline of the back, which bears a band of sharp, robust thorns. There are also a pair of thorn-bearing ridges in front of the eyes, a second pair running from above the eyes to behind the spiracles, and a third pair on the "shoulders". This species is bluish to brownish gray above, lightening towards the margins of the head and over the pectoral fins. 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. The underside is light gray to white. Young rays are more vividly colored than adults, which are browner with fainter patterning and proportionately smaller spots.

Distribution and habitat

While uncommon, ''Rhina ancylostoma'' is widely distributed in the coastal

waters of the western

. In the Indian Ocean, it is found from

KwaZulu-Natal KwaZulu-Natal (, also referred to as KZN and known as "the garden province") is a province of South Africa that was created in 1994 when the Zulu bantustan of KwaZulu ("Place of the Zulu" in Zulu) and Natal Province were merged. It is locate ...

in South Africa to the

Red Sea The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; T ...

(including the

Seychelles Seychelles (, ; ), officially the Republic of Seychelles (french: link=no, République des Seychelles; Creole: ''La Repiblik Sesel''), is an archipelagic state consisting of 115 islands in the Indian Ocean. Its capital and largest city, V ...

), across the

Indian subcontinent The Indian subcontinent is a list of the physiographic regions of the world, physiographical region in United Nations geoscheme for Asia#Southern Asia, Southern Asia. It is situated on the Indian Plate, projecting southwards into the Indian O ...

and

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...

(including the

Maldives Maldives (, ; dv, ދިވެހިރާއްޖެ, translit=Dhivehi Raajje, ), officially the Republic of Maldives ( dv, ދިވެހިރާއްޖޭގެ ޖުމްހޫރިއްޔާ, translit=Dhivehi Raajjeyge Jumhooriyyaa, label=none, ), is an archipelag ...

), to

Shark Bay Shark Bay (Malgana: ''Gathaagudu'', "two waters") is a World Heritage Site in the Gascoyne region of Western Australia. The http://www.environment.gov.au/heritage/places/world/shark-bay area is located approximately north of Perth, on the ...

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

. Its Pacific range extends northward to Korea and southern Japan, eastward to New Guinea, and southward to

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

. Found between deep, this ray spends most of its time near the

but can occasionally be seen swimming in midwater. It favors sandy or muddy

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s, and can also be found in the vicinity of rocky and

coral reef 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. Co ...

s and

shipwreck A shipwreck is the wreckage of a ship that is located either beached on land or sunken to the bottom of a body of water. Shipwrecking may be intentional or unintentional. Angela Croome reported in January 1999 that there were approximately ...

Biology and ecology

''Rhina ancylostoma'' is a strong swimmer that propels itself with its tail like a shark. It is more active at night and is not known to be territorial. This species feeds mainly on

demersal The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of ...

es such as

croakers Sciaenidae are a family of fish in the order Acanthuriformes. They are commonly called drums or croakers in reference to the repetitive throbbing or drumming sounds they make. The family consists of about 286 to 298 species in about 66 to 70 gene ...

and

s such as

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...

s and

shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...

;

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

s and

cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

s are also consumed. Its bands of flattened teeth allow it to crush hard-shelled prey. Curiously, two ''Rhina ancylostoma'' examined in a 2011

stable isotope The term stable isotope has a meaning similar to stable nuclide, but is preferably used when speaking of nuclides of a specific element. Hence, the plural form stable isotopes usually refers to isotopes of the same element. The relative abundanc ...

study were found to have fed on

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

rather than demersal animals, in contrast to previous observations. The

tiger shark The tiger shark (''Galeocerdo cuvier'') is a species of requiem shark and the last extant member of the family Galeocerdonidae. It is a large macropredator, capable of attaining a length over . Populations are found in many tropical and tempera ...

(''Galeocerdo cuvier'') is known to prey on ''Rhina ancylostoma''. The ray is protected by the thorns on its head and back, and it may ram perceived threats.

Parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

s documented from this species include the

tapeworm Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda (the other subclass is Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Cestodar ...

s '' Carpobothrium rhinei'', '' Dollfusiella michiae'', '' Nybelinia southwelli'', '' Stoibocephalum arafurense'', and '' Tylocephalum carnpanulatum'', the

leech Leeches are segmented parasitic or predatory worms that comprise the subclass Hirudinea within the phylum Annelida. They are closely related to the oligochaetes, which include the earthworm, and like them have soft, muscular segmented bodie ...

'' Pontobdella macrothela'', the

trematode Trematoda is a class of flatworms known as flukes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in which asexual reproduction occurs, is usually a snail. The definitive host ...

'' Melogonimus rhodanometra'', the

monogenea Monogeneans are a group of ectoparasitic flatworms commonly found on the skin, gills, or fins of fish. They have a direct lifecycle and do not require an intermediate host. Adults are hermaphrodites, meaning they have both male and female reprod ...

ns '' Branchotenthes robinoverstreeti'' and '' Monocotyle ancylostomae'', and the

copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (inhabiting sea waters), some are benthos, benthic (living on the ocean floor) ...

s '' Nesippus vespa'', '' Pandarus cranchii'', and '' P. smithii''. There is a record of a ''Rhina ancylostoma'' being cleaned by

bluestreak cleaner wrasse The bluestreak cleaner wrasse, ''Labroides dimidiatus'', is one of several species of cleaner wrasses found on coral reefs from Eastern Africa and the Red Sea to French Polynesia. Like other cleaner wrasses, it eats parasites and dead tissue o ...

s (''Labroides dimidiatus''). Reproduction in ''Rhina ancylostoma'' is

viviparous Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the m ...

, with the developing

embryo An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...

s sustained to term by

. Adult females have a single functional

ovary The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...

and

uterus The uterus (from Latin ''uterus'', plural ''uteri'') or womb () is the organ in the reproductive system of most female mammals, including humans that accommodates the embryonic and fetal development of one or more embryos until birth. The uter ...

. The litter size varies between two and eleven pups, and newborns measure long.

Sexual maturity Sexual maturity is the capability of an organism to reproduce. In humans it might be considered synonymous with adulthood, but here puberty is the name for the process of biological sexual maturation, while adulthood is based on cultural definitio ...

is attained at lengths of for males and over in females. Females grow larger than males.

Human interactions

Throughout its range, ''Rhina ancylostoma'' is caught incidentally or intentionally by

and

using

gillnet Gillnetting is a fishing method that uses gillnets: vertical panels of netting that hang from a line with regularly spaced floaters that hold the line on the surface of the water. The floats are sometimes called "corks" and the line with corks is ...

s, and line gear. The fins are extremely valuable due to their use in

shark fin soup Shark fin soup is a traditional soup or stewed dish served in parts of China, Taiwan, and Southeast Asia. The shark fins provide texture, while the taste comes from the other soup ingredients. It is commonly served at special occasions such as ...

, and are often the only parts of the fish kept and brought to market. However, the meat may also be sold fresh or dried and salted, and it is highly sought after in India. When caught as

bycatch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...

in trawls, ''Rhina ancylostoma'' is considered a nuisance because its strength and rough skin make it difficult to handle, and as the heavy ray thrashes in the net it can damage the rest of the catch. In Thailand, the enlarged thorns of this species are used to make bracelets. The

(IUCN) has assessed ''Rhina ancylostoma'' as Critically endangered in 2019, delisted from the vulnerable category, along with many other guitarfish species. It is threatened by fishing and by

habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

and

degradation Degradation may refer to: Science * Degradation (geology), lowering of a fluvial surface by erosion * Degradation (telecommunications), of an electronic signal * Biodegradation of organic substances by living organisms * Environmental degradation ...

, particularly from

blast fishing Blast fishing, fish bombing, dynamite fishing or grenade fishing is a destructive fishing practice using explosives to stun or kill schools of fish for easy collection. This often illegal practice is extremely destructive to the surrounding ec ...

coral bleaching Coral bleaching is the process when corals become white due to various stressors, such as changes in temperature, light, or nutrients. Bleaching occurs when coral polyps expel the zooxanthellae (dinoflagellates that are commonly referred to as alg ...

, and

siltation Siltation, is water pollution caused by 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 (temporary or ...

. Its numbers are known to have declined substantially in Indonesian waters, where it is one of the large rays targeted by a mostly unregulated gillnet fishery. The IUCN has given this species a regional assessment of

Near Threatened A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature as that may be vulnerable to endangerment in the near future, but it does not currently qualify fo ...

in Australian waters, where it is not a targeted species but is taken as bycatch in bottom trawls. The installation of

turtle excluder device A turtle excluder device (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 indus ...

s on some Australian trawlers has benefited this species. Since it is rare and faces many conservation threats, ''Rhina ancylostoma'' has been called "the

panda The giant panda (''Ailuropoda melanoleuca''), also known as the panda bear (or simply the panda), is a bear species endemic to China. It is characterised by its bold black-and-white animal coat, coat and rotund body. The name "giant panda" is ...

of the aquatic world". It is a popular subject of

s and fares relatively well, with one individual having lived for seven years in captivity. In 2007, the

Newport Aquarium The Newport Aquarium is an public aquarium, aquarium located in Newport, Kentucky, United States at Newport on the Levee, across the river from Cincinnati. It has 70 exhibits and 14 galleries, including five seamless acrylic tunnels totaling ov ...

Kentucky Kentucky ( , ), officially the Commonwealth of Kentucky, is a state in the Southeastern region of the United States and one of the states of the Upper South. It borders Illinois, Indiana, and Ohio to the north; West Virginia and Virginia to ...

initiated the world's first

captive breeding Captive breeding, also known as captive propagation, is the process of plants or animals in controlled environments, such as wildlife reserves, zoos, botanic gardens, and other conservation facilities. It is sometimes employed to help species that ...

program for this species. Newport Aquarium announced in January 2014 that the female, "Sweet Pea", had become pregnant and given birth to seven pups. By February 2014, all seven pups had died. On January 7, 2016, Sweet Pea gave birth to nine shark pups which were eating on their own and still gaining weight by February 10, 2016. Newport Aquarium later announced that the pups would be moved into a coral reef exhibit where they can be viewed by the public starting on June 24. The species also bred at the

S.E.A. Aquarium The Marine Life Park is a part of Resorts World Sentosa, Sentosa, situated in southern Singapore. The 8-hectare (20-acre) park houses two attractions, the S.E.A. Aquarium and the Adventure Cove Waterpark, and featured the largest oceanarium in ...

Singapore Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, borde ...

in 2015.

References

{{Taxonbar, from=Q1190545 Rajiformes Fish of the Red Sea Marine fauna of East Africa Fish described in 1801 Taxa named by Marcus Elieser Bloch