| Common names: ray (English), eagle ray (English), chucho (Espanol), gavilán (Espanol) |
Aetobatus narinari (Euphrasen, 1790)
Spotted eagle ray, Bonnet ray
Disc angular, nearly twice as wide as long, pectorals with pointed curved tips; head and snout strongly marked off from rest of disc; snout projecting, elongate and narrow; shallow V-shaped skin flap between nostrils and mouth; ridge around snout, not joined to pectoral fin; each jaw with one row of large plate-like crushing teeth; large notched skin fold between nostrils and mouth; moderate sized dorsal fin at tail base; no tail fin or fin folds; tail long and slender, with 2-6 spines at its base.
Dark grey to black with numerous white spots above, white below.
Size: disc width to 250 cm.
Habitat: often sighted alone or in small groups cruising around the perimeters of reefs, common in estuaries.
Depth: 1-80 m.
Cosmopolitan in tropical to warm temperate seas; southern Baja to the lower 3/4 of the Gulf of California to Ecuador, all the oceanic islands except Clipperton.
Global Endemism: All species, TEP non-endemic, Circumtropical ( Indian + Pacific + Atlantic Oceans), "Transpacific" (East + Central &/or West Pacific), All Pacific (West + Central + East), East Pacific + Atlantic (East +/or West), Transisthmian (East Pacific + Atlantic of Central America), East Pacific + all Atlantic (East+West)
Regional Endemism: All species, Eastern Pacific non-endemic, Tropical Eastern Pacific (TEP) non-endemic, Continent + Island (s), Continent, Island (s)
Climate Zone: Northern Subtropical (Cortez Province + Sinaloan Gap), Northern Tropical (Mexican Province to Nicaragua + Revillagigedos), Equatorial (Costa Rica to Ecuador + Galapagos, Clipperton, Cocos, Malpelo)
Aetobatus narinari (spotted eagle ray) is globally distributed throughout tropical and warm temperate waters as far north as North Carolina, U.S.A. in the summer and as far south as Brazil. This species has also been known to inhabit the red sea and oceanic waters surrounding the Hawaiian islands. Its latitudinal range spans from 43°N to 32°S.
Biogeographic Regions: indian ocean; atlantic ocean ; pacific ocean
Other Geographic Terms: cosmopolitan
Regularity: Regularly occurring
Type of Residency: Year-round
Many eagle rays (including Aetobatus narinari) have a flattened snout that protrudes from the pectoral disc. Aetobatus narinari can be distinguished by a pectoral disc that is approximately twice as wide as it is long. The posterior edge of the pectoral fins are concave and very angular tips (Bester, 2008). The ventral surface is white and the dorsal surface is either blue or black and peppered with white spots and rings. It has rounded pelvic fins and a very small dorsal fin but lacks a caudal fin all together. The pectoral fins make up a majority of the pectoral disc and are acutely angled at the lateral tips. Aetobatus narinari possesses stinging spines, which can be found behind the dorsal fin, and a slender whip-like tail that can be up to three times as long as the width of the pectoral disc (Bester, 2008). It can weigh as much as 230 kg and can reach disc widths of up to 330 cm; however, the average disc width of A. narinari is 180 cm. Sexual dimorphism has not been reported in this species.
Range mass: 230 (high) kg.
Range length: 330 (high) cm.
Average length: 180 cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry ; venomous
Inshore/Offshore: Inshore, Inshore Only
Water Column Position: Mid Water, Near Bottom, Bottom, Bottom + water column
Habitat: Reef associated (reef + edges-water column & soft bottom), Soft bottom (mud, sand,gravel, beach, estuary & mangrove), Sand & gravel, Estuary, Water column
FishBase Habitat: Bentho-Pelagic
Aetobatus narinari is a reef associated ray and is commonly found along reef edges. It prefers warm water with soft bottoms consisting usually of mud, sand and gravel. Aetobatus narinari spends most of its time around 60 m deep but may dive up 80 m deep. It is often seen in beach areas as well as estuaries and mangrove swamps throughout tropical regions of the world.
Range depth: 1 to 80 m.
Average depth: 60 m.
Habitat Regions: saltwater or marine
Aquatic Biomes: pelagic ; reef ; coastal ; brackish water
Other Habitat Features: estuarine
Habitat and Ecology
Around coral reef environments, spotted eagle rays often enter coral lagoons to feed (Pohnpei Island, Federated States of Micronesia; Homma et al. 1994). Diet consists of a wide variety of benthic species including polychaetes, bivalve and gastropod molluscs, cephalopods, crustaceans and teleost fishes (Homma and Ishihara 1994, Last and Stevens 1994, Compagno and Last 1999, McEachran and de Carvalho 2002) with fish important prey items for adults (Michael 1993).
Aplacental viviparous. Little information available on reproductive biology although known to have low fecundity, bearing 1 to 4 pups/litter (Last and Stevens 1994). Homma et al. (1994) observed three gravid females in the Caroline Islands, two individuals carrying a single embryo and one carrying two embryos. Gestation has been reported at 12 months (Michael 1993) and reproductive periodicity may not be annual. These factors combine for limited reproductive output. Reported to reach sexual maturity after 4 to 6 years (Last and Stevens 1994). Although reaches 330 cm DW most observed are less than 200 cm DW (Compagno and Last 1999).
Catches taken in the protective shark nets off the beaches of KwaZulu-Natal, South Africa, occur throughout the year but peak in summer (January and February) (Young 2001). The overall sex ratio is unity but there is a significant association between sex and time of year, with more males than females caught in summer and more females than males in winter. Median disc width for each sex is 100 cm (Young 2001). Catches are rare in the southern part of the netted region, an apparent consequence of lower water temperatures (Young 2001).
It should be recognised that life history parameters are likely to vary between the different forms of A. narinari, which may turn out to represent interspecific differences.
Life history parameters
Age at maturity: 4 to 6 years (Last and Stevens 1994) (female); 4 to 6 years (Last and Stevens 1994) (male).
Size at maturity (total length): Unknown (female); Between 100 and 115 cm DW (Indonesia; W. White unpubl. data) (male).
Longevity (years): Unknown.
Maximum size (total length): 330 cm DW (Last and Stevens 1994).
Size at birth: 26 cm DW (Last and Stevens 1994), 17 to 36 cm DW (Compagno and Last 1999).
Average reproductive age (years): Unknown.
Gestation time: 12 months (Michael 1993), but may be less..
Reproductive periodicity: Unknown.
Average annual fecundity or litter size: 1 to 4 pups/litter (Last and Stevens 1994).
Annual rate of population increase: Unknown.
Natural mortality: Unknown.
Habitat Type: Marine
Water temperature and chemistry ranges based on 15 samples.
Depth range (m): 1 - 67.5
Temperature range (°C): 22.006 - 27.331
Nitrate (umol/L): 0.289 - 2.763
Salinity (PPS): 34.443 - 36.251
Oxygen (ml/l): 4.302 - 4.855
Phosphate (umol/l): 0.110 - 0.424
Silicate (umol/l): 0.756 - 4.953
Depth range (m): 1 - 67.5
Temperature range (°C): 22.006 - 27.331
Nitrate (umol/L): 0.289 - 2.763
Salinity (PPS): 34.443 - 36.251
Oxygen (ml/l): 4.302 - 4.855
Phosphate (umol/l): 0.110 - 0.424
Silicate (umol/l): 0.756 - 4.953
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
From 1 to 80 meters.
Habitat: benthopelagic. Spotted eagle ray. Euphrasen, 1790
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Diet: mobile benthic worms, mobile benthic crustacea (shrimps/crabs), mobile benthic gastropods/bivalves, octopus/squid/cuttlefish
Primary prey of Aetobatus narinari consists of crustaceans, molluscs, echinoderms and polychaete worms. It is also known to occasionally consume smaller fish as well. When a prey item is captured, A. narinari crushes it between the upper and lower dental plates. Prior to ingestion, it uses 6 to 7 rows of papillae located on the roof of the mouth to remove indigestible items (e.g., shell and bone).
Animal Foods: fish; mollusks; aquatic or marine worms; aquatic crustaceans; echinoderms
Primary Diet: carnivore (Eats non-insect arthropods, Molluscivore , Vermivore)
Spotted eagle rays are predators of a variety of marine invertebrates and are important prey for a number of shark species. Information regarding parasites specific to this species is limited, however, ectoparasites such as marine leeches, are thought to be common. Endoparasites such as trematodes and tapeworms, are common as well.
- trematodes, (Thaumatocotyle pseudodasybatis)
- marine leech, (Branchellion torpedinis)
- tapeworms, (Acanthobothrium monski)
Silvertip sharks and great hammerheads, are important predators of spotted eagle rays. Sharks have also been reported to follow spotted eagle rays during the birthing season in order to feed on newborn pups. Similar to other cartilaginous fishes, spotted eagle rays have a network of electrosensory organs on their snout that helps them detect potential predators. In addition, all fish have a lateral line system that allows them to detect changes in temperature and pressure in their immediate environment.
- silvertip shark, (Carcharhinus albimarginatus)
- great hammerhead, (Sphyrna lewini)
Diseases and Parasites
Life History and Behavior
As with all cartilaginous fishes, Aetobatus narinari has specialized electrosensory organs commonly referred to as Ampullae of Lorenzini. These sensory organs consists of jelly-filled pores that create an electrosensory network along the snout, which increases the sensitivity of A. narinari to prey movement, as muscle contractions create an electrical pulse. In general, elasmobranchs have excellent vision and olfactory perception, which help them avoid predators and detect prey. In addition, all fish have a lateral line system that allows them to sense changes in pressure and temperature in the surrounding environment. There is no information available regarding intraspecific communication in Aetobatus narinari.
Perception Channels: visual ; chemical ; electric
Aetobatus narinari is ovoviviparous, as its eggs develop inside the uterus and hatch within the mother prior to emerging. Once the embryos are released from the egg, they are nourished by a yolk sac rather than through a placental connection with the mother. Little is known of the development of A. narinari. Newborn pups generally measure 17 to 35 cm in disc width.
There is no information available regarding the average life span of Aetobatus narinari.
Prior to mating, multiple Aetobatus narinari males chase a single females while grasping her dorsum with their upper tooth plate. A single male then grabs one of the female's pectoral fins and roles her into a vertical position and inserts his claspers. Copulation can last from 20 to 90 seconds and females have been known to repeat this process up to 4 times over a relatively short period of time. The mating system of Aetobatus narinari has not been clearly defined; however, the competitive behavior of males prior to copulations suggests polygyny.
Breeding season in Aetobatus narinari varies by location but usually occurs during mid-summer. Typically, females give birth to 2 pups per pregnancy but can have between 1 and 4. Gestation lasts for approximately 12 months, but can be short as 8 months depending on location and mean water temperature during gestation. Evidence suggests that A. narinari becomes sexually mature when they grow to about half their maximum disc width, which typically occurs between 4 and 6 years of age.
Breeding season: Aetobatus narinari breeds during summer.
Range number of offspring: 1 to 4.
Average number of offspring: 2.
Range gestation period: 8 to 12 months.
Average gestation period: 12 months.
Range age at sexual or reproductive maturity (female): 4 to 6 years.
Range age at sexual or reproductive maturity (male): 4 to 6 years.
Key Reproductive Features: seasonal breeding ; sexual ; fertilization (Internal ); ovoviviparous
Other than the in-utero protection and yolk sac a mother provides her young prior to birth, there is no information available regarding parental care in Aetobatus narinari.
Parental Investment: female parental care ; pre-hatching/birth (Provisioning: Female, Protecting: Female)
Molecular Biology and Genetics
Barcode data: Aetobatus narinari
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Aetobatus narinari
Public Records: 16
Specimens with Barcodes: 40
Species With Barcodes: 1
CITES: Not listed
Aetobatus narinari is listed as near threatened on the IUCN's Red List of Theatened Species. Although detailed accounts of its capture are limited, small litter sizes, schooling tendencies and inshore habitat preferences make this species particularly vulnerable to overfishing. In addition, in shore fishing gear (beach seine, gillnet, trawl etc.) is widely available and the practice of in shore fishing is largely unregulated, resulting in the IUCN's near threatened listing. In shore fishing pressure on A. narinari is particularly intense in southeast Asia. As a result, the IUCN classifies this species as vulnerable in this part of its geographic range.
Aetobatus narinari is protected in Australia, the Maldives, and Florida. Much of its geographic range in Australia's coastal waters includes the Great Barrier Reef, a third of which is protected against fishing. In addition, the use of turtle exclusion devices is mandatory in prawn trawl fisheries of Northern Australia, which likely decreases by-catch. The export of rays and ray skins was banned in the Maldives in 1995 and 1996, respectively. In addition, elasmobranchs are protected in marine reserves surrounding the Maldives that attract ecotourists interested in marine wildlife. Finally, A. narinari cannot be harvested, possessed, landed, purchased, sold or exchanged in Florida.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: near threatened
IUCN Red List Assessment
Red List Category
Red List Criteria
The 2000 Red List assessment for Aetobatus narinari incorrectly classified the species as "relatively fecund". Females bear a maximum of four pups/litter after a gestation period of probably a year. These limited biological parameters, the species' inshore habitat and hence availability to a wide variety of inshore fishing gear (beach seine, gillnet, purse seine, benthic longline, trawl etc.), its marketability and the generally intense and unregulated nature of inshore fisheries across large parts of the species' range warrant a global listing of Near Threatened, and a Vulnerable listing in Southeast Asia where fishing pressure is particularly intense and the species is a common component of landings (future declines of >30% are expected, if they have not already occurred). With further data it will likely fall into a threatened category in other regions also. For example, although specific details are not available, pressure on the inshore environment through artisanal fishing activities off West Africa, eastern Africa, throughout the Arabian Sea, the Bay of Bengal and in large portions of the species? American range has likely affected this species. There is nothing to suggest that pressure will decrease in these regions in the future. In a few parts of its range (e.g., South Africa, the Maldives, the USA and Australia) the species faces lower levels of threat, but overall, pressure on the species is high and likely to cause population depletions. Management and conservation measures considering harvest and trade management need to be implemented immediately.
- 2000Data Deficient
National NatureServe Conservation Status
Rounded National Status Rank: NNR - Unranked
NatureServe Conservation Status
Rounded Global Status Rank: GNR - Not Yet Ranked
This species occurs in coastal inshore waters where fishing pressure is typically very heavy, especially in SE Asian waters, in parts of Africa and through portions of the species' range in the Americas. The strong swimming nature of this species makes it quite susceptible to a range of fisheries, especially inshore gill net fisheries, which are extremely intensive in some regions (for example, Kalimantan in Indonesia). The species also enters estuarine waters where fishing pressure is also extremely high and where (in SE Asia at least) pollution is also a major factor for all marine life.
The species is likely to contribute substantially to numerous inshore artisanal fisheries across its range and it is known to be landed regularly in some places. In Southeast Asia, Aetobatus narinari is landed in most countries within its range, for example, Indonesia (W. White unpublished data), Thailand (Vidthayanon 2002), the Philippines (Compagno et al. 2005), Taiwan (W. White and P. Kyne pers. obs.) and Malaysia (Manjaji 2002), all of which are countries where fishing pressure on the inshore environment is intense and generally unregulated. In Indonesia the species is presently caught consistently but in only small numbers in many fisheries (W. White unpublished data) and expected future declines in SE Asia are the basis for the Vulnerable listing there. The species is probably widely utilized across its range (Compagno and Last 1999) due to its availability to fisheries. Fishing pressure on the inshore environment across most of the species' range is only likely to increase in the future.
Off eastern Africa, it is commonly caught by artisanal fishermen, in bottom set gillnets, trawls and longlines in Tanzania (Bianchi 1985), by artisanal gillnet fisheries off northern Madagascar (Doukakis and Jonahson 2003, Robinson in prep.) and by hook and line and harpoon off Somalia (Sommer et al. 1996).
Although specific details are not available, pressure on the inshore environment through artisanal fishing activities off West Africa, throughout the Arabian Sea, the Bay of Bengal and in large portions of the species' American range has likely affecting this species. There is nothing to suggest that pressure will decrease in these regions in the future.
In South Africa, between 1981 and 2000 there was a non-significant increasing trend in catch of A. narinari in the protective shark nets off KwaZulu-Natal (Young 2001). Of the mean annual catch of 16 animals, 82% were released alive. The species contributed 4.6% to the total batoid catch. Aetobatus narinari is taken in small numbers as bycatch in a shallow water prawn trawl fishery that operates off central KwaZulu-Natal (Fennessy 1994).
It is a popular public aquarium species and is collected for the marine aquarium trade. In some localities it is likely to be persecuted when considered a pest of mollusc aquaculture farms, as has occurred with other myliobatid species, for example Myliobatis californicus (Gray et al. 1997).
In a few parts of its range the species faces lower levels of threat. These include South Africa where catch levels are low, the USA where the species is protected in Florida (see Conservation Measures below), the Maldives where the exportation of ray product is banned, parts of Oceania where human populations are low, and Australia. The species is afforded some protection and impact reduction in parts of Australia in Marine Protected Areas, by the use of Turtle Exclusion Devices in prawn trawl fisheries and because of spiritual significance in some indigenous communities (see Conservation Measures). However, there is still concern for the species in Australia where it is taken as bycatch in inshore net fisheries and marketed as ?skate wings?, ?ray flaps? or ?eagle ray flaps?. Eagle ray is becoming an increasingly popular seafood product in Australia and the landing of this product is likely to increase in the future.
In addition to species-specific catch details, life history information including age, growth, longevity, movement patterns, habitat use, potential nursery areas, diet, and further reproductive studies are necessary to develop effective conservation actions for A. narinari. Direct estimates of fishing and natural mortality are critical for assessing fisheries impacts on a particular species.
Of highest priority is the resolution of taxonomic issues to better define the actual ranges of the various forms/species of the A. narinari species-complex.
A recent reduction in the number of protective shark nets off KwaZulu-Natal, South Africa, will help to limit catches in that region. The recreational line fishery in South Africa is managed by a bag limit of one/species/person/day for unspecified chondrichthyans, which includes A. narinari.
This species is protected in Florida State waters under the Florida Adminstrative Code, with the purpose of increasing public awareness of the need for extensive conservation action. As such, the spotted eagle ray cannot be harvested, possessed, landed, purchased, sold or exchanged in Florida.
The species is afforded protection on the east coast of Australia in the extensive Great Barrier Reef Marine Park (although only a third of the park is closed to commercial fishing) and the use of Turtle Exclusion Devices (TEDs) in prawn trawl fisheries across northern Australia is mandatory. TEDs are likely to decrease the catch of at least large individuals, as was shown for numerous batoid species by Stobutzki et al. (2002). The spiritual significance of these rays to some indigenous communities has limited traditional catches in parts of northern Australia (Puruntatameri et al. 2001).
In the Maldives, the species is afforded protection in marine reserves created around diving sites in recognition of the high value of sharks and rays to tourism (Anderson and Waheed 2001). The Maldives also banned the export of rays in 1995 and the export of ray skins in 1996. Again, this was to protect the tourism resource (Anderson and Waheed 2001).
The development and implementation of management plans (national and/or regional e.g., under the FAO International Plan of Action for the Conservation and Management of Sharks: IPOA-Sharks) are required to facilitate the conservation and management of all elasmobranch species. See Anon. (2004) for an update of progress made towards development and implementation of National Plans of Action for countries across the range of A. narinari.
Relevance to Humans and Ecosystems
Spotted eagle rays are capable of stinging humans with their venomous spine, which occasionally results in death. There are a few documented cases of spotted eagle rays jumping out of the water and onto boats.
Negative Impacts: injures humans (bites or stings, venomous )
Although spotted eagle rays are sometimes targeted for their meat, detailed accounts of captures are limited.
Positive Impacts: food
Spotted eagle ray
|This article's factual accuracy may be compromised due to out-of-date information. (June 2013)|
The spotted eagle ray (Aetobatus narinari) is a cartilaginous fish of the eagle ray family, Myliobatidae. It can be found globally in tropical regions, including the Gulf of Mexico, Hawaii, off the coast of West Africa, the Indian Ocean, Oceania, and on both coasts of the Americas at depths down to about 80 meters (262 ft). The rays are most commonly seen alone, but occasionally swim in groups. Rays 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. Its current genus name is Ateobatus, derived from the Greek words aetos (eagle) and batis (ray). The spotted eagle ray belongs to the Myliobatidae family, which includes the well known Manta ray. Most rays in the Myliobatidae swim in the open ocean rather than close to the sea floor.
Description and behavior
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. Their tails are longer than those of other rays and may have 2–6 venomous spines, just behind the pelvic fins. The front half of the long and wing-like pectoral disk has five small gills in its underside.
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.
The spotted eagle ray develops ovoviviparously; the eggs are retained in the female and hatch internally, feeding off a yolk sac until live birth. After a gestation period of one year the mother ray will give birth to a maximum of four pups. When the pups are first born, their discs measure from 170–350 millimeters (6.7–13.8 in) across. The rays mature in 4 to 6 years.
Feeding and diet
Spotted eagle ray preys mainly upon bivalves, crabs, whelks, benthic infauna they also feed on mollusks, crustaceans, particularly malacostracans. and also upon hermit crabs, shrimp, octopi, and some small fish.
The spotted eagle ray's specialized chevron-shaped tooth structure helps it to crush the mollusks' hard shells. 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. These rays have the unique behavior of digging with their snouts in the sand of the ocean.  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.
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, 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 traveling 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.
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. There are no target fisheries for the spotted eagle ray, but it is often eaten after being caught unintentionally as bycatch. There have been several reported incidents of spotted eagle rays leaping out of the water onto boats and landing on people. Nevertheless spotted eagle rays do not pose a significant threat to humans, as they are shy and generally avoid human contact. 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.
Predators and parasites
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. 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. Sharks have also been observed to follow female rays during the birthing season, and feed on the newborn pups.
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. External parasites include the monocotylid monogeneans Decacotyle octona, Decacotyle elpora and Thaumatocotyle pseudodasybatis on the gills.
Distribution and habitat
They are found in shallow coastal water by coral reefs and bays, in depths down to 80 meters (262 ft). 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 from the Red Sea to South Africa and also in northern Japan and Australia. 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.
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 state of Florida in the United States, the fishing, landing, purchasing and trading of spotted eagle ray is outlawed. The spotted eagle ray is also protected in the Great Barrier Reef on the eastern coast of Australia.
- Summers, Adam (2001). "Aetobatus narinari". Digital Morphology. Retrieved 1 November 2011.
- Kyne, P.M., Ishihara, H., Dudley, S. F. J. & White, W. T. (2006). Aetobatus narinari. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 24 February 2009.
- Kyne, Ishihara. "Aetobatus narinari". IUCN 2011. Retrieved 23 October 2011.
- Bester, Cathleen. "Ichtyology at the Florida Museum of Natural History". Florida Museum of Natural History. Retrieved 21 October 2011.
- Symbolae Antillanae : seu fundamenta florae Indiae Occidenttalis (in German). Berolini : Fratres Borntraeger ; Parisiis : Paul Klincksieck. Retrieved 2011-10-27.
- Fowler, Sarah L; Cavanagh, Rachael D (2005). "Species status report". Sharks, rays, chimaeras: The status of the Chondrichthyan fishes. UK: IUCN. p. 354. ISBN 2-8317-0700-5.
- Daley, R K; Stevens, J D; Last, P R; Yearsley, G. K. (October 2002). "Northern demersal species". Field guide to Australian sharks and rays. Australia: CSIRO Marine Research. p. 44. ISBN 1-876996-10-2.
- Tee-Van 1953, p. 453
- Australian Wildlife. "White-Spotted Eagle Ray". Retrieved 29 October 2011.
- Carpenter, Kent E.; Niem, Volker H. "The Living Marine Resources of the Western Central Pacific" 3. pp. 1511, 1516. Retrieved 30 October 2011.
- Froese, Rainer and Pauly, Daniel, eds. (2007). "Aetobatus narinari" in FishBase. April 2007 version..
- "Spotted Eagle Ray". Elasmodiver. 3 June 2007.
- Bester, Cathleen. "Eagle Ray Spotted Eagle Ray Aetobatus narinari". Retrieved 18 October 2011.
- Schluessel, Vera. "Life History, Population Genetics and Sensory Biology of the White Spotted Eagle Ray Aetobatus narinari (Euphrasen, 1790) with Emphasis on the Relative Importance of Olfaction". Retrieved 18 October 2011.
- Schluessel, V; Bennett, M. B.; Collin, S. P. "Diet and reproduction in the white-spotted eagle ray Aetobatus narinari from Queensland, Australia and the Penghu Islands, Taiwan". Retrieved 1 November 2011.
- SeaWorld; Discovery Cove; Busch Gardens. "Spotted Eagle Ray". Retrieved 1 November 2011.
- Silliman 1999, p. 5.
- Silliman 1999, pp. 5–6.
- CNN. "Woman dies after stingray strikes her". Cable News Network. A Time Warner Company. Retrieved 30 October 2011.
- CNN. "Ray slams woman on boat in Florida Keys". Cable News Network. A Time Warner Company. Retrieved 30 October 2011.
- Silliman 1999, p. 2.
- "Spotted Eagle Ray, Aetobatus narinari". marinebio.org. Retrieved 9 November 2011.
- Chapman 2002, p. 949.
- Moravec, F. & Justine, J.-L. 2006: Three nematode species from elasmobranchs off New Caledonia. Systematic Parasitology, 64, 131-145. doi:10.1007/s11230-006-9034-x
- Marie, A. D. & Justine, J.-L. 2005: Monocotylids (Monogenea: Monopisthocotylea) from Aetobatus cf. narinari off New Caledonia, with a description of Decacotyle elpora n. sp. Systematic Parasitology, 60, 175-185. doi:10.1007/s11230-004-6345-7
- Marie, A. D. & Justine, J.-L. 2006: Thaumatocotyle pseudodasybatis Hargis, 1955 (Monogenea: Monocotylidae) from Aetobatus cf. narinari, with a comparison of specimens from Australia, French Polynesia and New Caledonia. Systematic Parasitology, 64, 47-55. doi:10.1007/s11230-005-9017-3
- Carpenter, Kent E.; Niem, Volker H. (1999). "Batoid fishes". The Living Marine Resources of the Western Central Pacific. Batoid fishes, chimaeras and bony fishes 3. pp. 1511, 1516. ISBN 92-5-104302-7.
- Chapman, D.D.; Gruber, S.H. (May 2002). "A further observation of the prey-handling behavior of the great hammerhead shark, Sphyrna mokarran: predation upon the spotted eagle ray, Aetobatus narinari". Bulletin of Marine Science (pdf) 70 (3): 947–952. Retrieved 31 October 2011.
- Silliman, William R.; Gruber, S.H. (1999). "Behavioral Biology of the Spotted Eagle Ray, Aetobatus narinari (Euphrasen, 1790), in Bimini, Bahamas; an Interim Report" (pdf). Retrieved 31 October 2011.
- Tee-Van, John (1953). "Family Myliobatidae, Genus Aetobatus". Fishes of the western North Atlantic, part two. New Haven,Sears Foundation for Marine Research, Yale Univ. pp. 253–263. Retrieved 2011-10-27.
- Information and pictures of the spotted eagle ray
- White-spotted Eagle Ray, Aetobatus narinari (Euphrasén, 1790) – Australian Museum
- Species Description of Aetobatus narinari at www.shark-references.com
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