Zonetail butterfly ray | |
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Dorsal view of Gymnura zonura. [1] | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Chondrichthyes |
Subclass: | Elasmobranchii |
Order: | Myliobatiformes |
Family: | Gymnuridae |
Genus: | Gymnura |
Species: | G. zonura |
Binomial name | |
Gymnura zonura (Bleeker, 1852) | |
Range of the Zonetail butterfly ray [2] | |
Synonyms | |
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The zonetail butterfly ray (Gymnura zonura) is a species of fish in the family Gymnuridae. It is found in Indo-Pacific waters near India, Indonesia, Malaysia, the Philippines, Singapore, and Thailand. Its natural habitats are open seas, shallow seas, subtidal aquatic beds, and estuarine waters.
They have a mostly brown coloration on their dorsal side, with several small white spots throughout. Their ventral side exhibits white coloration and is entirely smooth-skinned. They can be differentiated from other Gymnuridae species by their tail, which displays 6-10 black bands along its length, separated by alternating white bands with single dark spots in between.
Zonetail butterfly rays feed on smaller organisms found on or near the sea floor such as bony fishes, crustaceans, and molluscs. They develop their offspring viviparously and can give birth to up to 4 live young per litter.
The Zonetail butterfly ray has a broad, depressed body shape and thin body size. Most of their characterizing shape is made up of a pair of wide pectoral fins (referred to as the disc). Their disc width is broader than their disc length. Their skin is smooth throughout, with the dorsal surface of the body being a uniformly brown color adorned with numerous small rounded white spots throughout. Their ventral surface is uniformly white. Zonetail butterfly rays have relatively small snouts and eyes, with their spiracles being placed slightly above the eye. [3]
In contrast to other Gymnuridae members, the Zonetail butterfly ray lacks tentacles on the inner posterior lining of their spiracles. The Zonetail can be further distinguished from other butterfly ray species by their slim, whip-like, and relatively long tails (2/3 snout-vent length.) The tail typically has around 6-10 black bands with alternating white bands along the length, as well as the presence of a small dorsal fin attached to the base of the tail. They have been observed to present with singular dark spots between each black tail band. The caudal sting of the Zonetail butterfly ray is typically underdeveloped and also presents with a small dorsal fin at its base. [1] [4] [5]
Some studies suggest the presence of sexual dimorphism within G. zonura, with the average disc width of adult males being 477 mm (18.8 in) and the disc width of adult females reaching up to 1060 mm (41.7 in) in recorded specimen, although this data is limited. [6] [7] Studies using morphological and mitochondrial DNA analyses indicate the Zonetail butterfly ray shares particularly close relation to the Longtail butterfly ray (G. poecilura), which can also be found distributed across the Indo-Pacific, and thus share many similar physiological and behavioral traits. [1] [3]
The Zonetail butterfly ray has been found to co-occur with other members of Gymnuridae–particularly the Longtail butterfly ray (G. poecilura) along Malaysian coasts. They are typically found inhabiting shallow coastal areas of warm temperate and tropical conditions, usually at depths of around 37 m (121.4 ft). Zonetail butterfly rays are typically bottom-dwelling, but are able to use their broad pectoral fins to traverse through the open seas. [7] [8] They are distributed throughout the Indo-Pacific region, having been observed near Brunei Darussalam; Cambodia; China; India; Indonesia (near the islands of Java, Bali, Kalimantan, Sumatera,) Malaysia; Myanmar; the Philippines; Singapore; Sri Lanka; Taiwan; Thailand; and Vietnam. [2] [7] [8] [9]
Zonetail butterfly rays, similar to other butterfly rays, exhibit viviparous embryonic development. Viviparity entails initial nourishment of the offspring by yolk, and then subsequently by uterine milk (histotroph) rich in proteins and lipids up until birth. In butterfly rays, reproduction occurs via internal fertilization, where the male inserts one of their two claspers into the female cloaca to deposit sperm to the eggs. [10] [11] Male claspers grow and calcify with maturity, while female ovaries grow and develop ovarian follicles with maturity. Zonetail butterfly rays have been observed to spawn around 2-4 pups per litter. [3] [12] Females have likely evolved to grow larger than males in order to increase their reproduction potential as live bearers (both producing larger and more young), a quality that has been observed in other Elasmobranchs. [13] There is little information on their rearing habits or duration of development, but other butterfly rays have been shown to exhibit year-round reproduction, with embryonic development lasting multiple months. [12] Zonetail butterfly rays are thought to be able to live up to 15 years, but information on this remains understudied. [2]
In general, butterfly rays are capable of both undulatory and oscillatory swimming locomotion. They exhibit multiple derived pectoral fin developments, such as lateral expansion, anteroposterior elongation of the pectoral girdle, and pectoral stiffening from radial calcification and cross-bracing of fin rays. [14] As a result of this, Zonetail butterfly rays can access both pelagic and benthic zones in aquatic environments, [15] but likely prefer spending more time near the benthos as indicated by their feeding habits and dictated by their inferior mouth type. They use smaller undulations of the pectoral fins near the benthos presumably to keep the surrounding sediment undisturbed, allowing for better detection of prey through use of their ventral lateral line. They exhibit more high-speed swimming when traversing through the water column via quick, powerful downstrokes. [15]
Beyond transportation, butterfly rays can make use of their larger pectoral fins to stun and pin prey to the floor for predation. [14]
Zonetail butterfly rays have been found to feed primarily on bony fish, particularly anchovies and ponyfishes. Their inferior mouth type and co-occurrence with Longtail butterfly rays indicate that they may also feed on some bottom-dwelling crustaceans and molluscs, but there currently exists limited observed data on this for G. zonura. [3] In general, Gymnuridae report with exhibiting piscivorous feeding of both meso-pelagic and benthic fish species. [12] Their ability to swim through multiple levels of the water column likely contributes to this range in diet. Particular feeding habits of the Zonetail butterfly ray, outside of Gymnuridae family trends, remains generally understudied.
As of 2020, the International Union for Conservation of Nature (IUCN) has listed the Zonetail butterfly ray as an Endangered species. They are primarily threatened by overfishing from commercial fisheries (via trawling) for use of raw materials, but are of relatively low value due to their small size compared to other rays. Their meat is typically sold for both human consumption and as bait for longline fishing. [2] Other fishing purposes including targeted artisanal and recreational activities, along with bycatch, also contribute to the overall anthropogenic threat that they face. Competition with other butterfly rays–particularly the Longtail butterfly ray–due to having similar feeding habits and overlapping distribution ranges may also play a role in their low abundance. [3] [7] [16] Zonetail butterfly rays may be especially sensitive to these pressures on abundance as a result of their low fecundity as well. The sparse amount of knowledge and attention on this particular species is likely a factor in the lack of focused conservation efforts for them.
The butterfly rays are the rays forming the genus Gymnura and the family Gymnuridae. They are found in warm oceans worldwide, and occasionally in estuaries.
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 deepwater stingray or giant stingaree is a species of stingray and the sole member of the family Plesiobatidae. It is widely distributed in the Indo-Pacific, typically over fine sediments on the upper continental slope at depths of 275–680 m (900–2,230 ft). This species reaches 2.7 m (8.9 ft) in length and 1.5 m (4.9 ft) in width. It has an oval pectoral fin disc with a long, flexible, broad-angled snout. Most of the entire latter half of its tail supports a distinctively long, slender, leaf-shaped caudal fin. Its coloration is dark above and white below, and its skin is almost completely covered by tiny dermal denticles.
The milk shark is a species of requiem shark, and part of the family Carcharhinidae, whose common name comes from an Indian belief that consumption of its meat promotes lactation. The largest and most widely distributed member of its genus, the milk shark typically measures 1.1 m (3.6 ft) long, and can be found in coastal tropical waters throughout the eastern Atlantic and the Indo-Pacific regions. Occurring from the surface to a depth of 200 m (660 ft), this species is common near beaches and in estuaries, and has been recorded swimming up rivers in Cambodia. Juveniles are known to inhabit tidal pools and seagrass meadows. The milk shark has a slender body with a long, pointed snout and large eyes, and is a nondescript gray above and white below. This shark can be distinguished from similar species in its range by the long furrows at the corners of its mouth, and seven to 15 enlarged pores just above them.
The zebra bullhead shark is a bullhead shark of the family Heterodontidae found in the central Indo-Pacific between latitudes 40°N and 20°S, from Japan and Korea to Australia. It is typically found at relatively shallow depths down to 50 m (160 ft), but off Western Australia, it occurs between 150 and 200 m. It can reach a length of 1.25 m (4.1 ft). The reproduction of this bullhead shark is oviparous.
The Australian weasel shark is an uncommon species of ground shark in the family Hemigaleidae. It inhabits shallow waters off northern Australia to a depth of 170 m (560 ft); smaller sharks frequent sand and seagrass habitat and shift to coral reefs as they grow older. A slim, drab species reaching a length of 1.1 m (3.6 ft), it has sickle-shaped fins with dark tips on the second dorsal fin and caudal fin upper lobe. Its upper teeth are broad with strong serrations only on the trailing edge. The lateral line along each side is prominent and exhibits a downward curve below the second dorsal fin.
The blackmouth catshark is a species of deepwater catshark, belonging yo the family Pentanchidae, common in the northeastern Atlantic Ocean from Iceland to Senegal, including the Mediterranean Sea. It is typically found over the continental slope at depths of 150–1,400 m (490–4,590 ft), on or near muddy bottoms. The youngest sharks generally inhabit shallower water than the older juveniles and adults. This slim-bodied species is characterized by the black interior of its mouth, a marbled pattern of pale-edged brownish saddles or blotches along its back and tail, and a prominent saw-toothed crest of enlarged dermal denticles along the upper edge of its caudal fin. It reaches lengths of 50–79 cm (20–31 in), with sharks in the Atlantic growing larger than those in the Mediterranean.
The longhead catshark or smoothbelly catshark is a species of shark, family Pentanchidae, the deepwater catsharks. This shark has a patchy distribution in the Indo-Pacific from Mozambique to southern Japan to northern Australia. It is found in water between 500 and 1,140 m deep. This species grows to 59 cm (23 in) long and is characterized by its extremely long and narrow snout, short abdomen, and long anal and caudal fins. In addition, a large area of the anterior ventral portion of its body lacks dermal denticles. The longhead catshark is oviparous and the only known cartilaginous fish that is normally hermaphroditic, with the majority of individuals having both the functional reproductive organs of one sex and the undeveloped reproductive organs of the opposite sex.
The banded eagle ray is a species of fish in the family Myliobatidae. The species was first described by Bloch and Schneider in 1801. As an elasmobranch, the banded eagle ray has a skeleton composed of cartilage. Like other eagle rays it has a depressiform, dorsoventrally flattened, shape to succeed in its benthic lifestyle. It preys mainly on benthic crustaceans, snails, and worms. Its natural habitats are open seas, shallow seas, and coral reefs. As of 2016, this species is classified as vulnerable by the IUCN. The main threats to the banded eagle ray are overfishing and habitat destruction.
The plain maskray or brown stingray, is a species of stingray in the family Dasyatidae. It is found in shallow, soft-bottomed habitats off northern Australia. Reaching 24 cm (9.4 in) in width, this species has a diamond-shaped, grayish green pectoral fin disc. Its short, whip-like tail has alternating black and white bands with fin folds above and below. There are short rows of thorns on the back and the base of the tail, but otherwise the skin is smooth. While this species possesses the dark mask-like pattern across its eyes common to its genus, it is not ornately patterned like other maskrays.
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.
The smooth butterfly ray is a species of cartilaginous fish in the family Gymnuridae. It is a member of the order Myliobatiformes, which contains 10 total families. Its natural habitats are shallow seas, subtidal aquatic beds, estuarine waters, and coastal saline lagoons. Its common name is derived from its compressed body, pectoral fins that are wider than their length, and overall diamond shape.
The longtail butterfly ray is a species of butterfly ray, family Gymnuridae, native to the Indo-Pacific from the Red Sea to southern Japan and western Indonesia. Growing up to 92 cm (36 in) across, this ray has a lozenge-shaped pectoral fin disc about twice as wide as long, colored brown to gray above with many small, light spots. The spiracles behind its eyes have smooth rims. This species can be identified by its tail, which is about as long as the snout-to-vent distance, lacks fins, and bears nine to twelve each of alternating black and white bands.
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 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 spiny butterfly ray or giant butterfly ray is a species of butterfly ray, family Gymnuridae, native to the shallow coastal waters of the Atlantic Ocean. A large ray that can measure over 2 m across, it may be distinguished from the sympatric smooth butterfly ray by the spine at the base of its tail and by a small tentacular structure on the margin of each spiracle. Slow-reproducing and valued for its meat, in recent decades its population has experienced a decline of over 30%, and it has become Critically Endangered in certain parts of its range.
The Jenkins' whipray is a species of stingray in the family Dasyatidae, with a wide distribution in the Indo-Pacific region from South Africa to the Malay Archipelago to northern Australia. This large species grows to 1.5 m (4.9 ft) across and has a broad, diamond-shaped pectoral fin disc and a whip-like tail without fin folds. It has a band of heart-shaped dermal denticles running from between the eyes to the tail on its upper surface, along with a characteristic row of large spear-like thorns along the midline. It is uniform yellowish brown above, becoming grayish on the tail past the stinging spine, and white below; there is apparently a spotted color variant that had previously been described as a different species, the dragon stingray.
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.
The Indonesian angelshark is a rare species of angelshark, family Squatinidae, known only from a few specimens collected from fish landing sites in southern Indonesia. It is thought to inhabit the deep waters of the continental slope. Reaching at least 1.34 m (4.4 ft) long, this species has a flattened, ray-like shape and a well-developed tail and caudal fin. It is characterized by the absences of fringes on its nasal barbels and thorns down the midline of its back, as well as by its relatively plain grayish-brown dorsal coloration with dark saddles beneath the dorsal fin bases and a black leading margin on the underside of the pectoral fins. The International Union for Conservation of Nature (IUCN) has classified it as Critically Endangered due to significant fishing pressure.
Mobula kuhlii, the shortfin devil ray, is a species of ray in the family Mobulidae. It is endemic to the Indian Ocean and central-west Pacific Ocean. It ranges from South Africa, Mozambique, Tanzania and the Seychelles in the west to the Philippines and Indonesia in the east, and southward to the northern coast of Australia.
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