This article's factual accuracy may be compromised due to out-of-date information.(June 2013) |
Spotted eagle ray | |
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Spotted eagle ray at Turks and Caicos | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Chondrichthyes |
Subclass: | Elasmobranchii |
Order: | Myliobatiformes |
Family: | Aetobatidae |
Genus: | Aetobatus |
Species: | A. narinari |
Binomial name | |
Aetobatus narinari | |
Range of spotted eagle ray as traditionally recognized, but see text | |
Synonyms [2] | |
Aetobatis latirostris Contents |
The spotted eagle ray (Aetobatus narinari) is a cartilaginous fish of the eagle ray family, Aetobatidae. As traditionally recognized, it is found globally in tropical regions, including the Atlantic, Pacific and Indian Oceans. Recent authorities have restricted it to the Atlantic (including the Caribbean and Gulf of Mexico) with other populations recognized as the ocellated eagle ray (A. ocellatus) and Pacific white-spotted eagle ray (A. laticeps). Spotted eagle rays are most commonly seen alone, but occasionally swim in groups. They are ovoviviparous, the female retaining the eggs then releasing the young as miniature versions of the parent.
This ray can be identified by its dark dorsal surface covered in white spots or rings. Near the base of the ray's relatively long tail, just behind the pelvic fins, are several venomous, barbed stingers. Spotted eagle rays commonly feed on small fish and crustaceans, and will sometimes dig with their snouts to look for food buried in the sand of the sea bed. These rays are commonly observed leaping out of the water, and on at least two occasions have been reported as having jumped into boats, in one incident resulting in the death of a woman in the Florida Keys. The spotted eagle ray is hunted by a wide variety of sharks. The rays are considered near threatened on the IUCN Red List. They are fished mainly in Southeast Asia and Africa, the most common market being in commercial trade and aquariums. They are protected in the Great Barrier Reef.
The spotted eagle ray was first described by Swedish botanist Bengt Anders Euphrasén as Raja narinari in 1790 from a specimen collected at an unknown location (possibly the coast of Brazil) during a trip he made to the Antilles, and was later classified as Stoasodon narinari. [1] [2] [3] Its current genus name is Aetobatus, derived from the Greek words aetos (eagle) and batis (ray). The spotted eagle ray belongs to the Myliobatidae, which includes the well known manta ray. Most rays in the family Myliobatidae swim in the open ocean rather than close to the sea floor. [2]
Although traditionally considered to have a circumglobal distribution in tropical oceans throughout the world, recent authorities have restricted the true Aetobatus narinari to the Atlantic Ocean based on genetic and morphologic evidence. [4] [5] [6] [7] The Indo-Pacific population is Aetobatus ocellatus and the East Pacific is Aetobatus laticeps . [6] [7]
The spotted eagle ray has many different common names, including white-spotted eagle ray, bonnet skate, bonnet ray, duckbill ray and spotted duck-billed ray. [8] [9] [10]
Spotted eagle rays have flat disk-shaped bodies, deep blue or black with white spots on top with a white underbelly, and distinctive flat snouts similar to a duck's bill. [11] Their tails are longer than other rays and may have 2–6 venomous spines, behind the pelvic fins. The front of the wing-like pectoral disk has five small gills in its underside. [12]
Mature spotted eagle rays can be up to 5 meters (16 ft) in length; the largest spotted eagle rays have a wingspan of up to 3 meters (10 ft) and a mass of 230 kilograms (507 lb). [13] [14]
One male, or sometimes several, will pursue a female. When one of the males approaches the female, he uses his upper jaw to grab her dorsum. The male will then roll the female over by grabbing one of her pectoral fins, which are located on either side of her body. Once he is on her ventral side, the male puts a clasper into the female, connecting them venter to venter, with both undersides together. The mating process lasts for 30–90 seconds. [2]
The spotted eagle ray develops ovoviviparously; the eggs are retained in the female and hatch internally, feeding off a yolk sac until live birth. [2] After a gestation period of one year the mother ray will give birth to a maximum of four pups. [1] When the pups are first born, their discs measure from 17–35 centimeters (6.7–13.8 in) across. [2] The rays mature in 4 to 6 years. [1] [15] Genetic evidence indicates that the spotted eagle ray can undergo consecutive parthenogenesis. [16]
Spotted eagle ray preys mainly upon bivalves, crabs, whelks and other benthic infauna. They also feed on mollusks (such as the queen conch) [17] and crustaceans, particularly malacostracans, [18] [19] as well as echinoderms, polychaete worms, [20] hermit crabs, [21] shrimp, octopuses, and some small fish. [22]
The spotted eagle ray's specialized chevron-shaped tooth structure helps it to crush the mollusks' hard shells. [13] [14] The jaws of these rays have developed calcified struts to help them break through the shells of mollusks, by supporting the jaws and preventing dents from hard prey. [23] These rays have the unique behavior of digging with their snouts in the sand of the ocean. [24] While doing this, a cloud of sand surrounds the ray and sand spews from its gills. One study has shown that there are no differences in the feeding habits of males and females or in rays from different regions of Australia and Taiwan. [19]
Spotted eagle rays prefer to swim in waters of 24 to 27 °C (75 to 81 °F). Their daily movement is influenced by the tides; one tracking study showed that they are more active during high tides. Uniquely among rays they dig with their snouts in the sand, [24] surrounding themselves in a cloud of sand that spews from their gills. They also exhibit two motions in which the abdomen and the pectoral fins are moved rapidly up and down: the pelvic thrust and the extreme pelvic thrust. The pelvic thrust is usually performed by a solitary ray, and repeated four to five times rapidly. The extreme pelvic thrust is most commonly observed when the ray is swimming in a group, from which it will separate itself before vigorously thrusting with its pectoral fins. The rays also performs dips and jumps; in a dip the ray will dive and then come back up rapidly, perhaps as many as five times consecutively. There are two main types of jump: in one, the ray propels itself vertically out of the water, to which it returns along the same line; the other is when the ray leaps at a 45 degree angle, often repeated multiple times at high speeds. When in shallow waters or outside their normal swimming areas the rays are most commonly seen alone, but they do also congregate in schools. One form of travelling is called loose aggregation, which is when three to sixteen rays are swimming in a loose group, with occasional interactions between them. A school commonly consists of six or more rays swimming in the same direction at exactly the same speed. [25]
The dorsal spots make the spotted eagle ray an aquarium attraction, although because of its large size it is likely kept only at public aquariums. [8] There are no target fisheries for the spotted eagle ray, but it is often eaten after being caught unintentionally as bycatch. [8] There have been several reported incidents of spotted eagle rays leaping out of the water onto boats and landing on people. [26] [27] Nevertheless, spotted eagle rays do not pose a significant threat to humans, as they are shy and generally avoid human contact. [2] Interactions with an individual snorkeler in the Caribbean has been reported especially in Jamaica involving one, two and even three spotted eagle rays. The rays may exhibit a behavior similar to human curiosity which allows the snorkeler to observe the eagle ray who may slow down so as to share more time with the much slower human observer if the human observer appears to be unthreatening or interesting to the spotted eagle ray.
Spotted eagle rays, in common with many other rays, often fall victim to sharks such as the tiger shark, the lemon shark, the bull shark, the silver tip shark, and the great hammerhead shark. [28] [29] A great hammerhead shark has been observed attacking a spotted eagle ray in open water by taking a large bite out of one of its pectoral fins, thus incapacitating the ray. The shark then used its head to pin the ray to the bottom and pivoted to take the ray in its jaws, head first. [30] Sharks have also been observed to follow female rays during the birthing season, and feed on the newborn pups. [2]
As other rays, spotted eagle rays are host to a variety of parasites. Internal parasites include the gnathostomatid nematode Echinocephalus sinensis in the spiral intestine. [31] External parasites include the monocotylid monogeneans Decacotyle octona, [32] Decacotyle elpora [32] and Thaumatocotyle pseudodasybatis [32] [33] on the gills.
As traditionally defined, spotted eagle rays are found globally in tropical regions from the Indo-Pacific region from the western Pacific Ocean, the Indian Ocean, and the western Atlantic Ocean. [34]
They are found in shallow coastal water by coral reefs and bays, in depths down to 80 meters (262 ft). [13] Spotted eagle rays are found in warm and temperate waters worldwide. In the western Atlantic Ocean it is found off the eastern coast of United States of America, the Gulf Stream, the Caribbean, and down past the southern part of Brazil. In the Indian Ocean, it is found from the Red Sea down to South Africa and eastward to the Andaman Sea. In the Western Pacific Ocean it can be found near Japan and north of Australia. [2] In the Central Pacific Ocean, it can be found throughout the Hawaiian Islands. In the Eastern-Pacific Ocean, it is found in the Gulf of California down through Puerto Pizarro, an area that includes the Galapagos Islands. Spotted eagle rays are most commonly seen in bays and reefs. They spend much of their time swimming freely in open waters, generally in schools close to the surface, and can travel long distances in a day. [2]
Within these regions, there are significant variations in genetics and morphology. [6] [4] [5] As a consequence, recent authorities have split it into three: This restricts the true spotted eagle ray (A. narinari) to the Atlantic, while the Indo-Pacific population is the ocellated eagle ray (A. ocellatus) and the East Pacific is the Pacific white-spotted eagle ray (A. laticeps). [6] [7]
The spotted eagle ray is included in the IUCN's Red List as "near threatened". The rays are caught mainly in Southeast Asia and Africa. They are also common in commercial marine life trade and are displayed in aquariums. Among the many efforts to help protect this species, South Africa's decision to deploy fewer protective shark nets has reduced the number of deaths caused by entanglement. South Africa has also placed restrictions on the number of rays that can be bought per person per day. In the U.S. state of Florida, the fishing, landing, purchasing and trading of spotted eagle ray are outlawed. This ray is also protected in the Great Barrier Reef on the eastern coast of Australia. [1]
In Europe there is a breeding program managed by the EAZA for spotted eagle rays to reduce the amount of wild caught individuals needed by public aquaria. From the start until 2018 Burgers' Zoo in the Netherlands kept the studbook. Since 2018, Wroclaw Zoo in Poland is the new studbook keeper. Burgers' Zoo was also the first place in Europe to breed with the species and in 2018 was the most successful breeder worldwide with over 55 births. [35] [36] [37]
The eagle rays are a group of cartilaginous fishes in the family Myliobatidae, consisting mostly of large species living in the open ocean rather than on the sea bottom.
The sand tiger shark, grey/gray nurse shark, spotted ragged-tooth shark, or blue-nurse sand tiger, is a species of shark that inhabits subtropical and temperate waters worldwide. It inhabits the continental shelf, from sandy shorelines and submerged reefs to a depth of around 191 m (627 ft). They dwell in the waters of Japan, Australia, South Africa, and the east coasts of North and South America. The sand tiger shark also inhabited the Mediterranean, however it was last seen there in 2003 and is presumed extinct in the region. Despite its common names, it is not closely related to either the tiger shark or the nurse shark.
Opahs, also commonly known as moonfish, sunfish, cowfish , kingfish, and redfin ocean pan are large, colorful, deep-bodied pelagic lampriform fishes comprising the small family Lampridae.
The great hammerhead is the largest species of hammerhead shark, belonging to the family Sphyrnidae, attaining an average length of 4.6 m (15 ft) and reaching a maximum length of 6.2 m (20 ft). It is found in tropical and warm temperate waters worldwide, inhabiting coastal areas and the continental shelf. The great hammerhead can be distinguished from other hammerheads by the shape of its "hammer", which is wide with an almost straight front margin, and by its tall, sickle-shaped first dorsal fin. A solitary, strong-swimming apex predator, the great hammerhead feeds on a wide variety of prey ranging from crustaceans and cephalopods, to bony fish, to smaller sharks. Observations of this species in the wild suggest that the cephalofoil functions to immobilize stingrays, a favored prey. This species has a viviparous mode of reproduction, bearing litters of up to 50 pups every two years.
The brownspotted grouper, also known as the brown spotted reef cod, brown-spotted rockcod, coral grouper or honeycomb cod, is a species of marine ray-finned fish, a grouper from the subfamily Epinephelinae which is part of the family Serranidae, which also includes the anthias and sea basses. It has an Indo-Pacific distribution but in the northern Indian Ocean this distribution is discontinuous. It forms part of a species complex with two closely related species in the genus Epinephelus.
The bigeye sand tiger is an extremely rare species of mackerel shark in the family Odontaspididae, with a possible worldwide distribution. A large, bulky species reaching at least 3.6 m (12 ft) in length, the bigeye sand tiger has a long bulbous snout, large orange eyes without nictitating membranes, and a capacious mouth with the narrow teeth prominently exposed. It can be distinguished from the similar smalltooth sand tiger by its teeth, which have only one lateral cusplet on each side, and by its uniformly dark brown color.
The round ribbontail ray or blotched fantail ray, is a species of stingray in the family Dasyatidae, found throughout the nearshore waters of the tropical Indo-Pacific, as well as off islands in the eastern Pacific. It is a bottom-dwelling inhabitant of lagoons, estuaries, and reefs, generally at a depth of 20–60 m (66–197 ft). Reaching 1.8 m (5.9 ft) across, this large ray is characterized by a thick, rounded pectoral fin disc covered by small tubercles on top, and a relatively short tail bearing a deep ventral fin fold. In addition, it has a variable but distinctive light and dark mottled pattern on its upper surface, and a black tail.
The spotted ratfish is a chimaera found in the north-eastern Pacific Ocean. Often seen by divers at night in the Pacific Northwest, this cartilaginous fish gets its characteristic name from a pointed rat-like tail. The ratfish lays leathery egg cases on the bottom of muddy or sandy areas, which are often mistaken by divers as something inanimate. While mainly a deep-water species, it occurs at shallower depths in the northern part of its range. The generic name, Hydrolagus, comes from the Greek words ὕδωρ, meaning water, and λαγώς/λαγῶς, meaning hare, and the specific name honors Alexander Collie, who was a ship surgeon and early naturalist. The spotted ratfish is common in much of its range, not typically eaten by humans, and is not commercially caught.
The sand devil or Atlantic angel shark is a species of angelshark, family Squatinidae, native to the northwestern Atlantic Ocean. It occurs off the eastern United States, in the northern Gulf of Mexico, and possibly in parts of the Caribbean Sea. This bottom-dwelling shark is found in shallow inshore waters in summer and fall, and deep offshore waters in winter and spring. The sand devil's flattened body and enlarged pectoral and pelvic fins give it a ray-like appearance. There is a band of enlarged thorns running along the middle of its back. It is gray or brown in color, with scattered small dark spots. This species reaches 1.2–1.5 m (3.9–4.9 ft) in length.
The longheaded eagle ray is a species of eagle ray in the family Myliobatidae. The longheaded eagle ray, like other members of the genus Aetobatus, is characteristically different from other genera of eagle rays, distinguished by their notched nasal curtain; complete, singular set of upper and lower teeth; and v-shaped teeth in the lower jaw. It is found in the tropical and warm temperate Indo-West Pacific. It formerly included populations in the northwest Pacific, but these were recognized as a separate species, Aetobatus narutobiei, in 2013. Longheaded eagle rays are benthopelagic fishes that feed on crustaceans, cephalopods, echinoderms, and small bony fishes. It is a poorly known species, but generally uncommon and considered endangered by the IUCN.
Aetobatus is a genus of eagle rays native to the Atlantic, Pacific and Indian Oceans. It was formerly placed in Myliobatidae, but is now placed in its own family Aetobatidae based on salient differences from myliobatids, especially the pectoral fins joining the head at the level of the eyes.
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 purple eagle ray is a species of fish in the family Myliobatidae. It was formerly considered endemic to Australia but is now known to be more widespread. Its natural habitat is the open seas where it has a patchy distribution, and the International Union for Conservation of Nature has assessed its conservation status as being "near-threatened".
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Guentherus is a genus of jellynose fishes, belonging to the Ateleopodidae family, with two recognized species:
Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only by muscles.
The ocellated eagle ray or the whitespotted eagle ray, Aetobatus ocellatus, is a species of cartilaginous fish in the eagle ray family Myliobatidae. It is found in the tropical Indo-West Pacific region. In the past it was included in the spotted eagle ray, a species restricted to the Atlantic after the split.
Aetobatus laticeps, the Pacific white-spotted eagle ray, is a species of cartilaginous fish in the eagle ray family Myliobatidae. It is found in the tropical East Pacific Ocean, ranging from Baja California to northern Peru, including the Galápagos. There has been recent evidence to suggest A.laticeps is in the Mexican tropical Pacific, more specifically in Chacahua Lagoon. However this evidence is insufficient and so the research being done on the spotted eagle rays in Chacahua Lagoon is working under the name A. narinari. Until 2014, it was included in the similar spotted eagle ray, but the two differ in genetics. Studies have been conducted to attempt to identify spot patterns at the individual level. A. laticeps and A. narinari both have white spots on the dorsal side of their dark body, making them difficult to differentiate. Following the split, A. narinari is restricted to the Atlantic, while the Indo-Pacific is inhabited by the closely related A. ocellatus.
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