Mangrove whipray

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Mangrove whipray
Himantura granulata 2.jpg
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Myliobatiformes
Family: Dasyatidae
Genus: Urogymnus
Species:
U. granulatus
Binomial name
Urogymnus granulatus
Himantura granulata rangemap.png
Range of the mangrove whipray [2]
Synonyms
  • Trygon granulataMacleay, 1883
  • Trygon ponapensis Günther, 1910
  • Himantura granulata(Macleay, 1883)

The mangrove whipray (Urogymnus granulatus) or whitetail stingray, is a species of stingray in the family Dasyatidae. It is widely distributed in the Indo-Pacific region from the Red Sea to northern Australia and Micronesia. A benthic inhabitant of shallow inshore waters, juvenile mangrove whiprays favor mangrove and estuarine habitats, while adults favor sandy to rocky areas in lagoons and coral reefs. This species can be identified by its thick, oval pectoral fin disc that is dark gray above with numerous white flecks, and by its relatively short, whip-like tail that is white past the stinging spine. It grows up to 1.4 m (4.6 ft) across.

Contents

Solitary in nature, the mangrove whipray preys mainly on small, bottom-dwelling bony fishes and invertebrates. It is, like other stingrays, aplacental viviparous, with the females nourishing their unborn young via histotroph ("uterine milk"). The mangrove whipray is caught for its meat, skin, and cartilage across much of its range. The International Union for Conservation of Nature (IUCN) has assessed it as Vulnerable globally and as Endangered in Southeast Asia, where its population has declined substantially due to intensive artisanal and commercial fisheries as well as widespread habitat degradation. In particular, juvenile rays have been disproportionately targeted by fishers and affected by the large-scale destruction of mangrove forests.

Taxonomy

Australian zoologist William John Macleay published the first scientific account of the mangrove whipray, a brief description of an immature female 86 cm (34 in) long caught off Port Moresby, Papua New Guinea, in an 1883 volume of Proceedings of the Linnean Society of New South Wales. He named it Trygon granulata, as he noted that the specimen's head and back were "covered with small granules". [3] In 1928, Gilbert Percy Whitley moved this species to the genus Himantura. [4] It is, however, now considered to be in the genus Urogymnus . [5]

Description

The mangrove whipray can be identified by its oval shape, dark body with small white spots, and short white tail. Mangrove whipray maldives.jpg
The mangrove whipray can be identified by its oval shape, dark body with small white spots, and short white tail.

The pectoral fin disc of the mangrove whipray is very thick and oval in shape, measuring 0.9–1.0 times as wide as long. The anterior margins of the disc are nearly straight and converge at a broad angle on the snout tip. The medium-sized, widely spaced eyes are immediately followed by the spiracles. Between the long, thin nostrils is a short, broad curtain of skin with a finely fringed posterior margin. The lower jaw is bow-shaped, and there are 0–5 papillae across the floor of the mouth. The teeth are arranged in a quincunx pattern and number 40–50 rows in the upper jaw and 38–50 rows in the lower jaw. There are five pairs of gill slits beneath the disc. The pelvic fins are small and narrow. [2] [4]

The tail is thick at the base and measures 1.5–2 times longer than the disc width. One or two dorsally positioned serrated stinging spines are located in the first third of the tail. Past the sting, the tail becomes thin and whip-like, without fin folds. The upper surface of the body and tail are roughened by tiny dermal denticles, which become larger towards the midline of the back and tail. In addition, one or two irregular rows of thorns are present along the dorsal midline from the head to the sting. The mangrove whipray is dark brown to gray above with many white dots and flecks, which become denser with increasing size. The dark coloration is due to a layer of mucus, without which the body is light orange-gray. The underside is white with small dark spots towards the disc margin. The tail abruptly becomes white past the sting. This species grows to 1.4 m (4.6 ft) across and over 3.5 m (11 ft) long. [2] [4]

Distribution and habitat

Adult mangrove whiprays can often be found in sandy or hard bottom habitats. Maldives animals 19.jpg
Adult mangrove whiprays can often be found in sandy or hard bottom habitats.

Although uncommon, the mangrove whipray seems to be widely distributed in the Indo-Pacific; it has been reported from the Red Sea, South Asia including the Maldives and the Andaman Islands, the Gulf of Thailand, the Malay Archipelago (except Sumatra), New Guinea and northern Australia, and various islands including Guam, Fiji, the Solomon Islands, and Micronesia. [1] [2] This bottom-dwelling species typically inhabits shallow water close to shore, though adults have also been recorded offshore to at least a depth of 85 m (279 ft). Juvenile rays frequent brackish habitats such as mangroves and estuaries. By contrast, adults prefer areas of sand, sand and rock rubble, or hard bottom, and are often found in lagoons or on coral reefs. [1] [2]

Biology and ecology

Rabbitfishes are among the prey consumed by the mangrove whipray. Siganus javus.jpg
Rabbitfishes are among the prey consumed by the mangrove whipray.

Unlike many of its relatives, the mangrove whipray is reportedly solitary in nature. [1] It is relatively inactive during the day, often resting half-buried in sand or atop coral heads, and actively forages for food at night. [2] [6] The electroreceptive ampullae of Lorenzini of this species have a sensitivity of 4 nV/cm and an effective range of 25 cm (10 in), enabling it to locate buried prey. [7] Juveniles feed mainly on small crustaceans, including prawns and crabs. [2] Adults prey on small benthic bony fishes, including rabbitfishes, gobies, blennies, wrasses, and damselfishes, as well as invertebrates, including peanut worms, crabs, octopuses, and bivalves. [4] [6] As in all stingrays, the mangrove whipray is aplacental viviparous, with the developing embryos being sustained by nutrient-rich histotroph ("uterine milk") produced by the mother. The newborns measure 14–28 cm (5.5–11.0 in) across, and males reach sexual maturity at 55–65 cm (22–26 in) across. [1] Known parasites of this species include the tapeworm Rhinebothrium himanturi , and another undescribed species in the same genus. [8]

Human interactions

The mangrove whipray is capable of injuring a human with its venomous sting. [6] It is occasionally caught in tangle nets and bottom trawls, and to a lesser extent on longlines; it is marketed for its meat, skin, and cartilage. [1] [5] Because of its inshore habitat preferences, this naturally uncommon species is highly susceptible to intensive artisanal and commercial fishing occurring across much of its range. In Southeast Asia, immature rays have been particularly affected by local fishing, as well as by habitat degradation from the widespread loss of mangrove forests. Additionally, the numbers of this species in the Arafura Sea have dropped significantly due to an Indonesian gillnet fishery targeting wedgefishes (Rhynchobatus), which involves over 600 vessels and has been increasingly operating illegally in Australian waters. These factors have led to an inferred decline of the Southeast Asian population by over 50%, leading the International Union for Conservation of Nature (IUCN) to give it a regional assessment of Endangered. The mangrove whipray is minimally threatened off northern Australia, where it is caught incidentally by the Northern Prawn Fishery (NPF) but only in small numbers following the mandatory adoption of Turtle Exclusion Devices (TEDs). As a result, the IUCN assessment for the Australian population is Least Concern. Globally, the IUCN has listed this species as Vulnerable. [1]

Related Research Articles

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The roughback whipray is a rare species of freshwater stingray in the family Dasyatidae, found over sandy bottoms in the Mae Klong and Chao Phraya Rivers of Thailand. Growing no more than 29 cm (11 in) across, this small ray has an oval pectoral fin disc and a whip-like tail without fin folds. It closely resembles the white-edge freshwater whipray in appearance, but can be distinguished by its coloration: light gray to dark orange-brown above and white below with a dark band along the lateral margins. Another identifying feature is a "pearl organ" at the center of the back, found in individuals of all ages. All of the original specimens of the roughback whipray were found with extensive wounds to the fins and tail. The International Union for Conservation of Nature (IUCN) has assessed this species as Endangered, citing the extensive habitat degradation and heavy fishing pressure within its limited range.

<span class="mw-page-title-main">Giant freshwater stingray</span> Species of cartilaginous fish

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<span class="mw-page-title-main">Estuary stingray</span> Species of cartilaginous fish

The estuary stingray, also called the estuary stingaree or brown stingray, is a species of stingray in the family Dasyatidae. Endemic to eastern Australia, it typically inhabits shallow, mangrove-lined tidal rivers, estuaries, and bays in southern Queensland and New South Wales. This yellow-brown to olive ray grows to at least 93 cm (37 in) across. It has a diamond-shaped pectoral fin disc and a mostly smooth, whip-like tail bearing both dorsal and ventral fin folds. It can additionally be identified by its long, narrow nostrils and the row of thorns along the midline of its back.

<span class="mw-page-title-main">Longnose stingray</span> Species of cartilaginous fish

The longnose stingray is a species of stingray in the family Dasyatidae, native to the western Atlantic Ocean from the southern Gulf of Mexico to Brazil. Found in coastal waters no deeper than 36 m (118 ft), this demersal species favors muddy or sandy habitats. The longnose stingray is characterized by its angular, rhomboid pectoral fin disc, moderately projecting snout, and whip-like tail with a dorsal keel and ventral fin fold. It typically grows to 1.25 m (4.1 ft) across and is brownish above and light-colored below.

<span class="mw-page-title-main">Marbled whipray</span> Species of cartilaginous fish

The marbled whipray is a little-known species of stingray in the family Dasyatidae, native to several freshwater rivers in Southeast Asia. This species has an oval pectoral fin disc with an elongated, pointed snout and a very long, whip-like tail without fin folds. It is characterized by numerous heart-shaped dermal denticles and tubercles on its upper surface, as well as a reticulated pattern of brown blotches on a light background. The maximum recorded disc width is 36 cm (14 in). The marbled whipray has been assessed as Endangered by the International Union for Conservation of Nature (IUCN); it is heavily threatened by fishing and habitat loss, degradation, and fragmentation.

<span class="mw-page-title-main">White-edge freshwater whipray</span> Species of cartilaginous fish

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<span class="mw-page-title-main">Spotted stingaree</span> Species of cartilaginous fish

The spotted stingaree is an uncommon species of stingray in the family Urolophidae, endemic to shallow waters along the coast of southern Australia. It favors rocky reefs and seagrass beds. This species can be readily identified by its nearly circular, dark-colored pectoral fin disc, adorned with a complex pattern of white or cream spots. Its eastern and western forms differ slightly in coloration and have been regarded as separate species. There is a skirt-shaped curtain of skin between its nostrils. Its tail is fairly thick and terminates in a short leaf-shaped caudal fin; a relatively large dorsal fin is present just in front of the stinging spine.

<span class="mw-page-title-main">Reticulate whipray</span> Species of fish

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<span class="mw-page-title-main">Pink whipray</span> Species of stingray in the family Dasyatidae

The pink whipray is a species of stingray in the family Dasyatidae, with a wide but ill-defined distribution in the tropical Indo-Pacific from southern Africa to Polynesia. It is a bottom dweller that generally inhabits shallow water under 70 m (230 ft) deep, in sandy areas associated with coral reefs. Individuals exhibit a high degree of fidelity to particular locations. The pink whipray has a diamond-shaped pectoral fin disc wider than long, with a broad-angled snout and a very long, whip-like tail without fin folds. It has only a few small thorns on its back and is uniform brownish to grayish pink in color, becoming much darker past the tail sting. This large ray can reach 1.8 m (5.9 ft) across and over 5 m (16 ft) long.

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<span class="mw-page-title-main">Freshwater whipray</span> Species of fish

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The tubemouth whipray is a little-known species of stingray in the family Dasyatidae, named for its distinctive, highly protrusible jaws. It is found in shallow, brackish water near mangrove forests and large river mouths along the coasts of southwestern Borneo and southern Sumatra. Measuring up to 1 m (3.3 ft) across, this species has a diamond-shaped pectoral fin disc with an elongated, pointed snout and broadly rounded outer corners. The upper surface of the disc is a plain grayish or brownish in color, and covered by small, flattened dermal denticles. The tubemouth whipray is relatively common at present, but is heavily pressured by habitat degradation and coastal fisheries. The International Union for Conservation of Nature (IUCN) has listed it as Vulnerable.

The Hortle's whipray is a little-known species of stingray in the family Dasyatidae, occurring in shallow estuaries and mud flats off southern New Guinea. This species, growing to 71 cm (28 in) across, has a heart-shaped pectoral fin disc with a long, pointed snout and minute eyes. It has a wide dorsal band of dermal denticles extending from in front of the eyes to the tail, as well as scattered sharp denticles on the snout. The underside of the disc is a distinctive bright yellow in color, sometimes with darker markings around the nostrils, mouth, and gill slits. The Hortle's whipray is threatened by extensive seine fisheries and habitat degradation, leading the International Union for Conservation of Nature (IUCN) to assess it as Near Threatened.

<span class="mw-page-title-main">Black-spotted whipray</span> Species of stingray in the family Dasyatidae

The black-spotted whipray is a species of stingray in the family Dasyatidae, found in coastal waters off southern New Guinea and northern Australia. Long thought to be a variant of the related brown whipray, this species has an angular, diamond-shaped pectoral fin disc and a whip-like tail without fin folds. It is characterized by its dorsal color pattern, which consists of a variably extensive covering of small, close-set dark, and sometimes also white, spots on a grayish brown background. In addition, the tail has alternating light and dark saddles past the stinging spine. This species reaches a maximum recorded width of 80 cm (31 in).

<span class="mw-page-title-main">Brown whipray</span> Species of cartilaginous fish

The brown whipray is a species of stingray in the family Dasyatidae, common in inshore, muddy habitats along the northern coast of Australia. It has often been confused in literature for the honeycomb stingray and the black-spotted whipray, which until recently was thought to be the same species. This species has an angular, diamond-shaped pectoral fin disc and a long, very thin tail without fin folds. It is plain brown above, sometimes with white dots or flecks near the edge of the disc, and white below; the tail is dark all over, with alternating dark and light bands near the tip. The maximum recorded disc width is 74 cm (29 in).

<span class="mw-page-title-main">Blackedge whipray</span> Species of cartilaginous fish

The blackedge whipray is a little-known species of stingray in the family Dasyatidae, found in the coastal waters of the Bay of Bengal and the Gulf of Mannar. Attaining a disc width of 1.8 m (5.9 ft), this species has a diamond-shaped disc with two small concavities on either side of the snout tip, and a long, whip-like tail without tail folds. It is characterized by large thorns with star-shaped bases scattered over the disc, and by the wide, black marginal bands on the underside of the disc. The International Union for Conservation of Nature (IUCN) currently lacks sufficient data to assess the blackedge whipray beyond Data Deficient.

<span class="mw-page-title-main">Leopard whipray</span> Species of cartilaginous fish

The leopard whipray is a little-known species of stingray in the family Dasyatidae, found in the Indian and Pacific Oceans from the Andaman Sea to the Coral Triangle. It is found close to shore at depths shallower than 70 m (230 ft), over soft substrates. Attaining a width of 1.8 m (5.9 ft), this species has a diamond-shaped pectoral fin disc with a pointed snout and an extremely long, whip-like tail without fin folds. Adult rays have a leopard-like dorsal pattern of dark brown rings on a yellowish brown background, as well as a row of enlarged, heart-shaped dermal denticles along the midline of the disc. Newborns and small juveniles have large, solid dark spots and few denticles. The leopard whipray is caught by fisheries in many parts of its range, primarily for meat.

<span class="mw-page-title-main">Honeycomb whipray</span> Species of cartilaginous fish

The honeycomb whipray is a species of stingray in the family Dasyatidae, found widely in the shallow coastal waters of the Indo-Pacific from India to the Malay Archipelago. This large species grows to 1.3 m (4.3 ft) across and has a diamond-shaped disc with rounded corners and a projecting, pointed snout. Its tail is long and whip-like, without fin folds. Adults have a striking dorsal color pattern consisting of large, dark brown rings and reticulations delineated by thin yellow lines, while juveniles have a pattern of large dark spots. This ray can also be distinguished from its similar relatives by an enlarged, pearl-like dermal denticle at the center of the back, which is followed by a few thorns. The International Union for Conservation of Nature (IUCN) has assessed the honeycomb whipray as endangered, as it faces heavy fishing pressure and habitat degradation across much of its range.

<span class="mw-page-title-main">Mumburarr whipray</span> Species of fish (stingray)

The mumburarr whipray is a species of whipray from northern Australia and southern Papua New Guinea, described in 2016.

References

  1. 1 2 3 4 5 6 7 Manjaji Matsumoto, B.M.; White, W.T.; Fahmi, Ishihara, H.; Morgan, D.L. (2020). "Urogymnus granulatus". IUCN Red List of Threatened Species . 2020: e.T161431A177282313. doi: 10.2305/IUCN.UK.2020-3.RLTS.T161431A177282313.en . Retrieved 19 November 2021.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  2. 1 2 3 4 5 6 7 Last, P.R.; Stevens, J.D. (2009). Sharks and Rays of Australia (second ed.). Harvard University Press. pp. 444–445. ISBN   978-0-674-03411-2.
  3. Macleay, W. (April 1883). "Contribution to a knowledge of the fishes of New Guinea. No. III". Proceedings of the Linnean Society of New South Wales. 7 (4): 585–598. doi: 10.5962/bhl.part.22766 .
  4. 1 2 3 4 Ishihara H.; Homma K.; Takeda Y.; Randall, J.E. (1993). "Redescription, distribution and food habits of the Indo-Pacific dasyatidid stingray Himantura granulata" (PDF). Japanese Journal of Ichthyology. 40 (1): 23–28. Archived from the original (PDF) on 2016-03-04. Retrieved 2011-11-12.
  5. 1 2 Froese, Rainer; Pauly, Daniel (eds.) (2018). "Urogymnus granulatus" in FishBase. October 2018 version.
  6. 1 2 3 Ferrari, A.; Ferrari, A. (2002). Sharks . Firefly Books. p.  222. ISBN   978-1-55209-629-1.
  7. Haine, O.S.; Ridd, P.V.; Rowe, R.J. (2001). "Range of electrosensory detection of prey by Carcharhinus melanopterus and Himantura granulata". Marine and Freshwater Research. 52 (3): 291–296. doi:10.1071/MF00036.
  8. Williams, H.H. (November 1964). "Some new and little known cestodes from Australian elasmobranchs with a brief discussion on their possible use in problems of host taxonomy". Parasitology. 54 (4): 737–748. doi:10.1017/S0031182000082743. PMID   14227634. S2CID   19595399.