Crossback stingaree | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Chondrichthyes |
Subclass: | Elasmobranchii |
Superorder: | Batoidea |
Order: | Myliobatiformes |
Family: | Urolophidae |
Genus: | Urolophus |
Species: | U. cruciatus |
Binomial name | |
Urolophus cruciatus (Lacépède, 1804) | |
Range of the crossback stingaree [2] | |
Synonyms | |
Raja cruciataLacepède, 1804 Contents |
The crossback stingaree or banded stingaree (Urolophus cruciatus) is a species of stingray in the family Urolophidae. It is endemic to southeastern Australia, mainly off Victoria and Tasmania but also marginally to New South Wales and South Australia. This bottom-dwelling fish generally inhabits sand and reef habitats deeper than 100 m (330 ft) off Victoria, and muddy habitats in shallow bays and estuaries off Tasmania. Befitting its name, the crossback stingaree has a distinctive dark pattern on its back, consisting of a midline stripe that is crossed by three transverse bars. It has an oval pectoral fin disc with a blunt snout and a skirt-shaped curtain of skin between the nostrils. Its tail is short with no skin fold along the sides, and a deep, leaf-shaped caudal fin. The youngest rays may have a small dorsal fin in front of the stinging tail spine. This species reaches 50 cm (20 in) in length.
During the day the crossback stingaree is usually inactive and can be found partially or completely buried in sand on the sea floor. [3] It is a carnivore and adults forage for crustaceans, polychaete worms and other small invertebrates on the seafloor. [3] Juveniles feed on smaller crustaceans such as isopods, amphipods and shrimps.
The species is aplacental viviparous, with the developing embryos sustained to term by histotroph ("uterine milk") produced by the mother. Females bear litters of up to four pups every other year, after a gestation period of at least six months. This species is closely related to, and may hybridize with, the yellowback stingaree (U. sufflavus). The venomous sting of the crossback stingaree is potentially injurious to humans. This common species is seldom caught by commercial fisheries other than in the northernmost extent of its range. Thus, its population is largely secure and the International Union for Conservation of Nature (IUCN) has listed it under Least Concern.
French naturalist Bernard Lacépède originally described the crossback stingaree as Raja cruciata, in an 1804 volume of the scientific journal Annales du Muséum d'Histoire Naturelle Paris. The specific epithet means "cross-like" in Latin, referring to the distinctive markings on its back. The origin of the type specimen was given simply as New Holland (Australia). [4] In their 1838–41 Systematische Beschreibung der Plagiostomen, German biologists Johannes Müller and Jakob Henle placed this species in the newly created genus Urolophus. [5]
The Victorian and Tasmanian subpopulations of the crossback stingaree differ markedly in habitat preferences and merit further taxonomic investigation, according to the International Union for Conservation of Nature (IUCN). [1] This ray is closely related to the yellowback stingaree (U. sufflavus). In addition to morphological similarities, the two may also hybridize (see below) and, in a 2007 study of 388 fishes by Robert Ward and Bronwyn Holmes, were the only species that could not be distinguished on the basis of their cytochrome c gene sequences, attesting to a close evolutionary relationship. [2] [6]
The distribution of the crossback stingaree mainly encompasses the coastal waters of Victoria and Tasmania, where it is quite abundant; it ranges as far east as Jervis Bay in New South Wales, and as far west as Beachport in South Australia. Bottom-dwelling in nature, this species has been reported from the intertidal zone to a depth of 210 m (690 ft) on the upper continental slope. [1] [2] Rays of the Victorian subpopulation prefer sandy flats and rocky reefs and are seldom seen in less than 25 m (82 ft) of water, occurring most commonly at depths greater than 100 m (330 ft). [1] [7] By contrast, rays of the Tasmanian subpopulation are usually found over muddy bottoms in very shallow bays and large estuaries, occasionally penetrating into brackish water. [1] [8]
The crossback stingaree's pectoral fin disc is slightly wider than long and oval in shape, with the anterior margins nearly straight and converging at a very obtuse angle. The snout is fleshy and blunt, generally not protruding from the disc. The eyes are small and immediately followed by teardrop-shaped spiracles, which have rounded to angular posterior rims. The outer rim of each nostril may form a small knob at the back. Between the nostrils is a skirt-shaped curtain of skin with a deeply fringed posterior margin. The mouth is small and strongly arched, containing 3–6 papillae (nipple-like structures) on the floor and an additional patch of papillae is present on the outside of the lower jaw. [2] Both upper and lower teeth are small with roughly oval bases, and are arranged in a quincunx pattern. The five pairs of gill slits are short. The pelvic fins are small, with rounded margins. [9]
The rather short tail measures 63–84% of the disc's length and is a flattened oval in cross-section, without lateral skin folds. A single serrated, stinging spine is positioned on top, about halfway along the tail's length. [2] In newborns, the sting is preceded by a small dorsal fin; the fin is lost with age, though it may be evidenced by a small ridge or scar. At the end of the tail is a very short, deep, leaf-shaped caudal fin. [10] The skin is entirely devoid of dermal denticles. The crossback stingaree is grayish to yellowish brown above with a pattern of dark markings, including a stripe running along the midline and crossed by three transverse bars: one near the eyes, one over the gill region, and one over the center of the disc. The pattern is strongest in rays from the southern portion of its range. A few dark brown or black individuals have been recorded. The underside is off-white, sometimes becoming slightly darker at the disc margin. The caudal fin is more grayish than the body, and there may be dusky blotches on the tail. This species attains a maximum known length of 50 cm (20 in). [2] Females generally grow larger than males. [7]
Generally nocturnal, the crossback stingaree spends long stretches of the day lying motionless on the sea floor, partially or completely buried in sediment. [2] [11] It has been known to form groups of varying size, sometimes mixing with other stingaree species. [12] This ray is a generalist predator that forages for small organisms on or buried in the bottom. Off Victoria, over three-quarters of prey consumed are crustaceans, of which isopods (particularly Natalolana woodjonesi and N. wowine) comprise the majority and amphipods and decapods the remainder. Polychaete worms are also eaten in significant quantities, while priapulids and the burrowing squid Euprymna tasmanica are infrequently taken. Young rays under 30 cm (12 in) across feed mainly on smaller isopods, amphipods, and shrimps; with age a progressively greater diversity of larger prey, such as penaeid prawns, priapulids, and polychaetes, are incorporated into its diet. [7]
The broadnose sevengill shark (Notorynchus cepedianus) is known to prey on the crossback stingaree. [13] When threatened, this ray raises its tail warningly above its body in a scorpion-like fashion. [11] Parasites documented from this species include a tapeworm in the genus Acanthobothrium, [14] and the monogenean Calicotyle urolophi. [15] Like other stingrays, the crossback stingaree is aplacental viviparous: when the developing embryos exhaust their supply of yolk, their mother provisions them with nutrient-rich histotroph ("uterine milk") through specialized extensions of the uterine epithelium called "trophonemata". [7] Females produce litters of 1–4 pups every other year. Embryonic development proceeds rapidly over a six-month period, though the total gestation period may be much longer if there is a period of dormancy for the eggs after fertilization, as has been reported in other stingarees. [2] Off Tasmania, large estuaries such as at the mouth of the River Derwent serve as nursery areas. [8]
Different authors have variously reported the birth length at between 10 and 15 cm (3.9 and 5.9 in), and the maturation length at between 20 and 32 cm (7.9 and 12.6 in), with females usually maturing at a slightly larger size than males. This range of sizes may reflect life history differences in crossback stingarees across different parts of its range. [1] [2] [7] Both sexes mature at around six years of age, and can live to at least 11 years. [7] The crossback stingaree may hybridize naturally with the closely related yellowback stingaree off southern New South Wales, where the distributions of the two species overlap and apparent hybrid offspring with intermediate colour patterns have been found. If true, this would represent one of the few known cases of hybridization among cartilaginous fishes. [6]
The crossback stingaree can inflict an excruciating injury on an unwary human with its venomous sting, that may require surgical intervention if the serrated tip of the sting breaks off inside the wound. The base of its tail is highly flexible, allowing it to strike a person touching any part of its body. [2] In the 19th century, the hazard posed by this species led to persecution by fishery workers in the form of "spiking", in which a metal spike is used to pierce the ray's cranium and remove it from the net. [10] The IUCN has listed the crossback stingaree under Least Concern, as it is exposed to minimal fishing activity in the Bass Strait and off western Tasmania, which constitute most of its distribution. The impact of Tasmanian inshore fisheries is unquantified but unlikely to be severe. Off New South Wales, it is caught incidentally in otter trawls and gillnets used by the Southern and Eastern Scalefish and Shark Fishery (SESSF). Captured rays likely experience high mortality, and also tend to abort any unborn young. While the SESSF has caused an overall decline in deepwater stingarees within its area of operations, it only affects a small portion of this species' range. [1]
The Urolophidae are a family of rays in the order Myliobatiformes, commonly known as stingarees or round stingrays. This family formerly included the genera Urobatis and Urotrygon of the Americas, which are presently recognized as forming their own family Urotrygonidae. Stingarees are found in the Indo-Pacific region, with the greatest diversity off Australia. They are sluggish, bottom-dwelling fish that have been recorded from shallow waters close to shore to deep waters over the upper continental slope. Measuring between 15 and 80 cm long, these rays have oval to diamond-shaped pectoral fin discs and relatively short tails that terminate in leaf-shaped caudal fins, and may also have small dorsal fins and lateral skin folds. Most are smooth-skinned, and some have ornate dorsal color patterns.
The coastal stingaree is an uncommon species of round ray in the stingaree family, Urolophidae, that is endemic to the eastern Great Australian Bight.
The western shovelnose stingaree is a common species of stingray in the family Urolophidae, inhabiting shallow sandy flats and seagrass beds off southwestern Australia from Perth to Gulf St Vincent. Growing to 37 cm (15 in) long, this small ray has a rounded pectoral fin disc and a blunt, broadly triangular snout. Its nostrils have enlarged lobes along the outer rims and a skirt-shaped curtain of skin between them with a strongly fringed posterior margin. Its tail ends in a lance-like caudal fin and lacks dorsal fins and lateral skin folds. This species is colored grayish to brownish above, sometimes with lighter and darker spots, and pale below, sometimes with darker marginal bands and blotches.
The striped stingaree is a common but little-known species of stingray in the family Urolophidae, endemic to shallow, inshore waters off southwestern Australia. Reaching 61 cm (24 in) long, this species is characterized by an oval, grayish to brownish disc with darker mask-like markings around the eyes and paired blotches at the center of the disc that are extended posteriorly into horizontal lines. Its nostrils have enlarged lobes on the outer margins and a skirt-shaped curtain of skin with a deeply fringed trailing margin in between. Its tail terminates in a relatively large leaf-shaped caudal fin, and bears a small dorsal fin just before the stinging spine. The rounded, flexible disc of the striped stingaree enable it to maneuver through the rocks, reefs, and seagrass that comprise its favored habitats. The International Union for Conservation of Nature (IUCN) has listed this species under Least Concern; it is seldom caught by fisheries due to its habitat preferences.
The masked stingaree is a common species of stingray in the family Urolophidae, endemic to southwestern Australia. It prefers moderately deep areas of sand or seagrass some distance from shore, though it can be found in very shallow water or to a depth of 115 m (377 ft). The masked stingaree can be identified by the two large, dark blotches on the upper surface of its rounded pectoral fin disc, one of which encompasses its eyes like a mask. The outer rims of its nostrils are expanded into prominent lobes, while between the nostrils is a skirt-like curtain of skin with a deeply fringed trailing margin. Its tail bears a small dorsal fin just before the stinging spine, and end in a leaf-like caudal fin. This species grows up to 31 cm (12 in) across.
The common stingaree is a species of stingray in the family Urolophidae. The most abundant ray in inshore waters off eastern Australia, it generally inhabits estuaries, sandy flats, and rocky reefs from the shore to a depth of 60 m (200 ft). This plain brownish to grayish species has a rounded pectoral fin disc with a broadly triangular snout. Its nostrils have enlarged lobes on their outer margins and a skirt-shaped curtain of skin with a fringed posterior margin between them. Its tail bears a small dorsal fin before the stinging spine, and terminates in a leaf-shaped caudal fin. This ray can grow to 52 cm (20 in) long.
Urolophus is a genus of round rays mostly native to the western Pacific Ocean and the Indian Ocean, though one species occurs in the Pacific waters of the Mexican coast. Müller and Henle erected Urolophus in an 1837 issue of Bericht Akademie der Wissenschaften zu Berlin. The name is derived from the Greek oura, meaning "tail", and lophos, meaning "crest". In Urolophus, the outer rims of the nostrils are not enlarged into lobes, but may form a small knob at the back.
The sandyback stingaree or great stingaree is a little-known species of stingray in the family Urolophidae, endemic to southeastern Australia. It is generally found offshore around the edge of the continental shelf, at a depth of 65–265 m (213–869 ft). A relatively large species reaching 89 cm (35 in) long, the sandyback stingaree has a diamond-shaped pectoral fin disc wider than long, usually with a dorsal pattern of numerous fine lighter marks on a yellowish to brownish background. Its short tail terminates in a deep, leaf-shaped caudal fin, and bears a sizable dorsal fin just in front of the stinging spine.
The circular stingaree is an uncommon, little-known species of stingray in the family Urolophidae. Endemic to the coastal waters of southwestern Australia, it prefers a rocky and/or vegetated habitat. Reaching 60 cm (24 in) in length, this species is characterized by an oval pectoral fin disc bearing a striking dorsal pattern of lighter spots and rings, and a central circle of white-margined black spots, on a bluish gray background. Between its nostrils is a skirt-shaped curtain of skin, with the posterior corners drawn out into lobes. Its tail bears a rather large dorsal fin in front of the stinging spine, and ends in a deep, lance-like caudal fin. Negligibly affected by human activity, the circular stingaree has been listed under Least Concern by the International Union for Conservation of Nature (IUCN).
The wide stingaree is a little-known species of stingray in the family Urolophidae, found off southwestern Australia. It typically occurs over sand in water 200–300 m (660–980 ft) deep around the edge of the continental shelf. This species has a broad diamond-shaped pectoral fin disc, a slightly pointed snout, and a tail with a leaf-like caudal fin, skin folds along either side, and no dorsal fins. Between its nostrils is a skirt-shaped curtain of skin. It is grayish green above, with faint bluish lines beside and behind the eyes. The maximum length on record is 52 cm (20 in).
The patchwork stingaree is a little-known species of stingray in the family Urolophidae, with a disjunct distribution off northwestern and northeastern Australia. It usually inhabits the outer continental shelf, at a depth of 60–320 m (200–1,050 ft). This species has a diamond-shaped pectoral fin disc much wider than long, and a short, flattened tail with a prominent dorsal fin and leaf-like caudal fin. There is a skirt-shaped curtain of skin between its nostrils. Its dorsal colour pattern resembles a mosaic of dark brown rings with light-coloured centers, separated by fine reticulated lines. The International Union for Conservation of Nature (IUCN) has listed the patchwork stingaree under Least Concern, as it is subject to minimal fishing pressure.
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.
The lobed stingaree is a common species of stingray in the family Urolophidae, endemic to southern Western Australia in shallow, inshore sand and seagrass habitats. This species is plain sandy in colour above and has a broad, rounded pectoral fin disc. It is characterized by an enlarged, semicircular skin lobe of unknown function on the inner rim of each nostril. Its tail is slender, with lateral skin folds and a lance-like caudal fin but no dorsal fin. The maximum recorded width is 27 cm (11 in).
The mitotic stingaree or blotched stingaree, is a little-known species of stingray in the family Urolophidae, so named because it has light blue blotches on its back that resemble cells undergoing mitotic division. Though not uncommon, it is found only in a small area of the outer continental shelf off northwestern Australia, at around 200 m (660 ft) down. This species attains a length of 29 cm (11 in) long and has a diamond-shaped pectoral fin disc with broadly rounded corners and a skirt-shaped curtain of skin between the nostrils. Its tail has subtle skin folds running along either side, no dorsal fin, and a slender leaf-shaped caudal fin. The International Union for Conservation of Nature (IUCN) has listed the mitotic stingaree under Least Concern, as there is little fishing within its range.
The sparsely spotted stingaree, also known as the white-spotted stingaree or Dixon's stingaree, is a species of stingray in the family Urolophidae, common off the southern Australian coast. Preferring sandy flats and seagrass beds, this benthic ray can be found from close to shore to a depth of at least 150 m (490 ft), and tends to occur deeper in the northern portion of its range. Reaching a length of 57 cm (22 in), this species has a broad, diamond-shaped pectoral fin disc that is typically plain gray in color above with a V-shaped marking between the eyes. Individuals from southerly waters also generally exhibit a smattering of small, dark-edged white spots. This ray is further characterized by a distinctively bell-shaped curtain of skin between the nostrils. Its tail has a skin fold running along either side and a leaf-shaped caudal fin, but no dorsal fin.
The Coral Sea stingaree is a little-known species of stingray in the family Urolophidae, found at a depth of 171–310 m (561–1,017 ft) around the edge of the continental shelf off northern Queensland. Growing to a length of 48 cm (19 in), this species has a diamond-shaped pectoral fin disc with a protruding snout and a skirt-shaped flap of skin between the nostrils. Its tail bears a low dorsal fin before the stinging spine and terminates in a short leaf-shaped caudal fin. Its upper surface is grayish or brownish, sometimes with tiny dark spots. The Coral Sea stingaree may represent two closely similar species, one large and one small. There is very little fishing activity within its range, and thus it has been listed under Least Concern by the International Union for Conservation of Nature (IUCN).
The Kapala stingaree is a species of stingray in the family Urolophidae, endemic to inshore waters off southeastern Queensland and New South Wales. It is commonly found on and around rocky reefs at a depth of 10–130 m (33–427 ft). Reaching 51 cm (20 in) in length, the Kapala stingaree has a rounded, diamond-shaped pectoral fin disc and a slender tail, which ends in a leaf-shaped caudal fin and bears lateral skin folds and a small dorsal fin in front of the stinging spine. It has a distinctive bell-shaped curtain of skin between its nostrils. This species is greenish above, with a highly variable pattern of dark markings usually found outside and between the eyes, and over the back and tail.
The yellowback stingaree is a locally abundant but little-known species of stingray in the family Urolophidae. It is almost endemic to New South Wales, with a range from Green Cape northward, extending only barely into Queensland. It inhabits soft-substrate habitats and has been reported from depths of 45–300 metres (150–980 ft), though it is most common on the outer continental shelf at depths of 100–160 metres (330–520 ft).
The greenback stingaree is a little-known species of stingray in the family Urolophidae, endemic to the outer continental shelf and upper continental slope off southeastern Australia. Growing to a length of 51 cm (20 in), this species has a diamond-shaped pectoral fin disc wider than long and uniformly light green in color above. Between its nostrils is a skirt-shaped curtain of skin. Its tail bears skin folds on either side and a deep, lanceolate caudal fin, but lacks a dorsal fin.
The brown stingaree is a little-known species of stingray in the family Urolophidae, found at a depth of 60–220 m (200–720 ft) on the outer continental shelf off northern Western Australia. This species has a rhomboid pectoral fin disc colored light yellow or brown, sometimes with three faint, darker, transverse bars. Its nostrils have a skirt-shaped curtain of skin between them. Its tail ends in a leaf-shaped caudal fin and either lacks or has poorly developed lateral skin folds and a dorsal fin. The maximum known length is 36 cm (14 in). The International Union for Conservation of Nature (IUCN) has listed the brown stingaree under Least Concern, as there is negligible fishing pressure across most of its range.