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Overview

Brief Summary

Biology

Large groups of spotted eagle rays may be seen outside of the breeding season. These rays swim close to the surface and can occasionally be seen jumping clear out of the water (known as 'breaching') (2). Females give birth to around 4 live young (2). Spotted eagle rays have heavy dental plates which they use to crush their hard-shelled prey (4); they feed predominantly on bivalve shellfish (2).
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Description

The spotted eagle ray is very distinctive with a flattened body and triangular corners to the wing-like pectoral fins (2). The snout is rounded and pointed at the tip, so that it resembles a bird's beak. The tail is long and whip-like and bears 2 – 6 spines (3). These eagle rays posses highly attractive colouring; the uppersurface is blackish-blue with many white spots, whilst the underside is white (2). This colouration provides the spotted eagle ray with good camouflage in the water, whether viewed from above or below (4).
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Comprehensive Description

Description

  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.
   
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Biology

Commonly found in shallow inshore waters such as bays and coral reefs but may cross oceanic basins (Ref. 9862). Benthopelagic, found near land at 1-60 m (Ref. 58302). Sometimes enters estuaries (Ref. 6871). Swims close to the surface, occasionally leaping out of the water, or close to the bottom (Ref. 3175). Frequently forming large schools during the non-breeding season (Ref. 7251). Feeds mainly on bivalves but also eats shrimps, crabs, octopus and worms, whelks, and small fishes (Ref. 9862). Ovoviviparous (Ref. 50449). Flesh edible (Ref. 30573). Over 3 m disc width and up to 880 cm total length if the long tail is undamaged (Ref. 30573). Bears young in litters of 2-4 (Ref.58048,Ref. 26938). Tail used as a decorative item (Ref. 27550). Common catch of the demersal tangle net, bottom trawl, inshore gillnet and, to a lesser extent, demersal longline fisheries. Utilized for its meat and cartilage (Ref.58048).
  • Last, P.R. and J.D. Stevens 1994 Sharks and rays of Australia. CSIRO, Australia. 513 p. (Ref. 6871)
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Distribution

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

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Range Description

Widespread in tropical and warm temperate waters. Aetobatus narinari is probably a species-complex with different forms having more restricted ranges than the presently considered wide-ranging single species.
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N.C. (summer), Bermuda, se. Florida, and n. Gulf of Mexico to Brazil; nearly worldwide in tropical waters
  • North-West Atlantic Ocean species (NWARMS)
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Zoogeography

See Map (including site records) of Distribution in the Tropical Eastern Pacific 
 
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)

Residency: Resident

Climate Zone: Northern Subtropical (Cortez Province + Sinaloan Gap), Northern Tropical (Mexican Province to Nicaragua + Revillagigedos), Equatorial (Costa Rica to Ecuador + Galapagos, Clipperton, Cocos, Malpelo)
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Western Atlantic: North Carolina (summer) and Florida, USA and Bermuda to southern Brazil. Throughout Gulf of Mexico and Caribbean, including Antilles (Ref. 26938). Eastern Atlantic: Mauritania to Angola (Ref. 4440). Indo-West Pacific: Red Sea and South Africa to Hawaii, north to Japan, south to Australia (Ref. 9862). Eastern Pacific: Gulf of California to Puerto Pizarro, Peru and the Galapagos Islands (Ref. 5530). There may be more than one species of spotted Aetobatus (Ref. 9862). Based on combined genealogical concordance and genetic distance criteria,
  • Robins, C.R. and G.C. Ray 1986 A field guide to Atlantic coast fishes of North America. Houghton Mifflin Company, Boston, U.S.A. 354 p. (Ref. 7251)
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Circumglobal in tropical through warm temperate seas (including Red Sea, Seychelles, Madagascar, Mascarenes, Hawaiian Islands).
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Depth

Depth Range (m): 1 (S) - 80 (S)
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Range

Found throughout the world's tropical oceans; there is ongoing research as to whether different populations are genetically distinct enough to constitute separate species (3).
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National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Physical Description

Morphology

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

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Dorsal spines (total): 0; Dorsal soft rays (total): 0; Analspines: 0; Analsoft rays: 0
  • Myers, R.F. 1991 Micronesian reef fishes. Second Ed. Coral Graphics, Barrigada, Guam. 298 p. (Ref. 1602)
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Size

Length max (cm): 250.0 (S)
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Size

Maximum size: 3000 mm WD
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Max. size

330 cm WD (male/unsexed; (Ref. 58048)); max. published weight: 230.0 kg (Ref. 7251)
  • Robins, C.R. and G.C. Ray 1986 A field guide to Atlantic coast fishes of North America. Houghton Mifflin Company, Boston, U.S.A. 354 p. (Ref. 7251)
  • White, W.T., P.R. Last, J.D. Stevens, G.K. Yearsley, Fahmi and Dharmadi 2006 Economically important sharks and rays of Indonesia. [Hiu dan pari yang bernilai ekonomis penting di Indonesia]. Australian Centre for International Agricultural Research, Canberra, Australia. (Ref. 58048)
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Diagnostic Description

Description

Usually found in shallow inshore waters. Common around bays, estuaries, off beaches and coral reefs but may cross oceanic basins (Ref. 9862). Swims close to the surface, occasionally leaping out of the water, or close to the bottom (Ref. 3175). Frequently forms large schools during the nonbreeding season (Ref. 7251). Feeds mainly on bivalves but also eats shrimps, crabs, octopus and worms, whelks, and small fishes (Ref.9862).
  • Anon. (1996). FishBase 96 [CD-ROM]. ICLARM: Los Baños, Philippines. 1 cd-rom pp.
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An eagleray with a long snout, flat and rounded like a duck's bill, a thick head, and a pectoral disc with sharply curved, angular corners, and no caudal fin; jaws usually with single row of flat, chevron-shaped teeth (Ref. 5578). Each tooth a crescent-shaped plate joined into a band (Ref. 26938). Numerous white spots on black or bluish disc; white below (Ref. 5578). Long whiplike tail, with a long spine near the base, behind small dorsal fin. No spines on disk (Ref. 7251).
  • Myers, R.F. 1991 Micronesian reef fishes. Second Ed. Coral Graphics, Barrigada, Guam. 298 p. (Ref. 1602)
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Ecology

Habitat

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

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Habitat and Ecology

Habitat and Ecology
Coastal and semipelagic over the continental shelf from the surface to 60 m depth. Sometimes enters lagoons and estuaries and often associated with coral-reef ecosystems (Michael 1993, Homma et al. 1994, Last and Stevens 1994). Solitary or found in large schools of up to several hundred individuals (McEachran and de Carvalho 2002). Although primarily observed near the coast and around islands and reefs, the species is likely to be capable of crossing ocean basins (Compagno and Last 1999).

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.

Systems
  • Marine
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Habitat Type: Marine

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nektonic
  • North-West Atlantic Ocean species (NWARMS)
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Environment

reef-associated; amphidromous (Ref. 51243); brackish; marine; depth range 1 - 80 m (Ref. 9710), usually 1 - ? m (Ref. 55257)
  • Riede, K. 2004 Global register of migratory species - from global to regional scales. Final Report of the R&D-Projekt 808 05 081. Federal Agency for Nature Conservation, Bonn, Germany. 329 p. (Ref. 51243)
  • Lieske, E. and R. Myers 1994 Collins Pocket Guide. Coral reef fishes. Indo-Pacific & Caribbean including the Red Sea. Haper Collins Publishers, 400 p. (Ref. 9710)
  • Florida Museum of Natural History 2005 Biological profiles: spotted eagle ray. Retrieved on 26 August 2005, from www.flmnh.ufl.edu/fish/Gallery/Descript/SERay/SERay.html. Ichthyology at the Florida Museum of Natural History: Education-Biological Profiles. FLMNH, University of Florida. (Ref. 55257)
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Depth range based on 57 specimens in 1 taxon.
Water temperature and chemistry ranges based on 15 samples.

Environmental ranges
  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

Graphical representation

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.

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Depth: 1 - 80m.
From 1 to 80 meters.

Habitat: benthopelagic. Spotted eagle ray.   Euphrasen, 1790 
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Salinity: Marine, Brackish

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
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The spotted eagle ray is found in coastal waters in shallow bays and coral reefs, it has been recorded from a range of depths from 1 – 80 metres (2).
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Migration

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.

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Amphidromous. Refers to fishes that regularly migrate between freshwater and the sea (in both directions), but not for the purpose of breeding, as in anadromous and catadromous species. Sub-division of diadromous. Migrations should be cyclical and predictable and cover more than 100 km.Characteristic elements in amphidromy are: reproduction in fresh water, passage to sea by newly hatched larvae, a period of feeding and growing at sea usually a few months long, return to fresh water of well-grown juveniles, a further period of feeding and growing in fresh water, followed by reproduction there (Ref. 82692).
  • Riede, K. 2004 Global register of migratory species - from global to regional scales. Final Report of the R&D-Projekt 808 05 081. Federal Agency for Nature Conservation, Bonn, Germany. 329 p. (Ref. 51243)
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Trophic Strategy

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)

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Commonly found in shallow inshore waters such as bays and coral reefs but may cross oceanic basins (Ref. 9862). Benthopelagic, found near land at 1-60 m (Ref. 58302). Sometimes enters estuaries (Ref. 6871). Swims close to the surface, occasionally leaping out of the water, or close to the bottom (Ref. 3175). Frequently forming large schools during the non-breeding season (Ref. 7251). Feeds mainly on bivalves but also eats shrimps, crabs, octopus and worms, whelks, and small fishes (Ref. 9862). A carnivore (Ref. 9137).
  • Randall, J.E. 1967 Food habits of reef fishes of the West Indies. Stud. Trop. Oceanogr. Miami 5:665-847.
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Feeding

Feeding Group: Carnivore

Diet: mobile benthic worms, mobile benthic crustacea (shrimps/crabs), mobile benthic gastropods/bivalves, octopus/squid/cuttlefish
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Associations

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.

Commensal/Parasitic Species:

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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.

Known Predators:

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Diseases and Parasites

Thaumatocotyle Infestation 3. Parasitic infestations (protozoa, worms, etc.)
  • Hargis, W.J. 1955 Monogenetic trematodes of Gulf of Mexico fishes. Part V. The superfamily Capsaloidea. Trans. Am. Micro. Soc. 74(3):203-225. (Ref. 46261)
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Life History and Behavior

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

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Life Cycle

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.

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Exhibit ovoviparity (aplacental viviparity), with embryos feeding initially on yolk, then receiving additional nourishment from the mother by indirect absorption of uterine fluid enriched with mucus, fat or protein through specialised structures (Ref. 50449). Bears up to 4 young (Ref. 5578, 6871, 37816). Width at birth 17-35 cm (Ref. 37816).According to Uchida et al (1990) (Ref. 51119) 'the male chases the female in mid water, then nibbles on her dorsal surface. The female stops swimming to begin copulation. The male bites the female on a pectoral fin and bends one clasper forward, then attempts an abdomen to abdomen copulation with either clasper, usually mid-water' (Ref. 49562). Copulation lasted for 20 seconds to 1 minute (Ref. 49562).
  • Breder, C.M. and D.E. Rosen 1966 Modes of reproduction in fishes. T.F.H. Publications, Neptune City, New Jersey. 941 p. (Ref. 205)
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Life Expectancy

There is no information available regarding the average life span of Aetobatus narinari.

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Reproduction

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)

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Egg Type: Live birth, No pelagic larva
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Molecular Biology and Genetics

Molecular Biology

Barcode data: Aetobatus narinari

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 8 barcode sequences available from BOLD and GenBank.

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.

GGTACTGGTCTT---AGTCTACTAATCCGCACAGAATTAAGCCAACCCGGAGCCTTACTGGGTGAT---GACCAGATCTATAATGTAATCGTCACGGCCCATGCCTTTGTAATGATCTTTTTCATAGTTATACCCATCATAATTGGTGGATTCGGAAACTGGCTTGTCCCTCTTATA---ATTGGCGCCCCTGACATAGCTTTTCCTCGAATAAACAACATAAGCTTCTGACTTCTGCCCCCATCATTCCTACTTCTGCTGGCTTCAGCGGGAGTAGAAGCAGGGGCTGGGACTGGGTGAACAGTTTATCCCCCACTAGCCGGCAACCTGGCACATGCTGGTGCCTCAGTCGACCTA---ACCATTTTTTCCTTACATTTAGCAGGGGTGTCTTCGATTCTGGCATCTATCAACTTCATCACCACAATTATTAATATGAAACCACCAGCCATCTCCCAATACCAAACACCCTTGTTTGTTTGATCCATCCTCATTACAGCAGTACTTCTTCTCCTCTCCCTCCCAGTCCTAGCAGCA---GGAATCACAATACTTCTTACGGACCGGAACCTTAACACAACC
-- end --

Download FASTA File

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Statistics of barcoding coverage: Aetobatus narinari

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 16
Specimens with Barcodes: 40
Species With Barcodes: 1
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Conservation

Conservation Status

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

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IUCN Red List Assessment


Red List Category
NT
Near Threatened

Red List Criteria

Version
3.1

Year Assessed
2006

Assessor/s
Kyne, P.M., Ishihara, H, Dudley, S.F.J. & White, W.T.

Reviewer/s
Fowler, S.L. & Compagno, L.J.V. (Shark Red List Authority)

Contributor/s

Justification
A large eagle ray with a widespread distribution across the Indo-Pacific and eastern and western Atlantic in tropical and warm-temperate waters. Recorded over the continental shelf from the surface to 60 m depth in coastal and open ocean environments. Sometimes enters lagoons and estuaries and is often associated with coral-reef ecosystems. The presently known Aetobatus narinari is most probably a species-complex of at least four different species. However, it is here considered as a single species as presently recognised. Taxonomic resolution of this issue is of priority as each form will have a more restricted range than the presently described wide-ranging species, which will alter the potential affects of threatening processes on each subpopulation.

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.

History
  • 2000
    Data Deficient
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National NatureServe Conservation Status

United States

Rounded National Status Rank: NNR - Unranked

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NatureServe Conservation Status

Rounded Global Status Rank: GNR - Not Yet Ranked

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IUCN Red List: Listed, Near threatened

CITES: Not listed
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Status

Classified as Near Threatened (NT) on the IUCN Red List (1).
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Population

Population
Population structure of the various forms will likely differ and will need to be considered on a species by species basis once taxonomic issues are resolved.

Population Trend
Decreasing
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Threats

Major Threats
Details of catches of this species throughout its range are scant. Nevertheless its small litter size, schooling behaviour, 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. With further data it will likely fall into a threatened category in other regions also.

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.
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Near Threatened (NT)
  • IUCN 2006 2006 IUCN red list of threatened species. www.iucnredlist.org. Downloaded July 2006.
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Little data is available on spotted eagle ray populations. This species is however, accidentally caught as by-catch of the fishing industry in much of its range (1).
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Management

Conservation Actions

Conservation Actions
Fisheries taking A. narinari are generally unmanaged throughout large parts of the species' range. Attempts to monitor and regulate fisheries in these regions would greatly improve conservation of this and other chondrichthyans. Monitoring (including species-specific catch details) of any directed elasmobranch landings and bycatch are necessary to provide valuable information on the population status of these rays. Fishery-independent surveys of this and other elasmobranchs are necessary to provide estimates of abundance and biomass.

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.
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Conservation

Further research into population densities and distribution is needed before the precise threats to this species can be assessed and the appropriate conservation action adopted (1).
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Relevance to Humans and Ecosystems

Benefits

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 )

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Although spotted eagle rays are sometimes targeted for their meat, detailed accounts of captures are limited.

Positive Impacts: food

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Importance

fisheries: minor commercial; gamefish: yes; price category: medium; price reliability: very questionable: based on ex-vessel price for species in this family
  • Stehmann, M. and R. Vergara R. 1978 Myliobatidae. In W. Fischer (ed.) FAO Species Identificaiton Sheets for Fishery Purposes. Western Central Atlantic (fishing area 31). Vol. 5. [pag. var.]. FAO, Rome. (Ref. 3173)
  • Compagno, L.J.V. 1997 Myliobatidae. Eagle rays. p. 1511-1519. In K.E. Carpenter and V.H. Niem (eds.) FAO species identification guide for fishery purposes. The living marine resources of the Western Central Pacific. Vol. 3. Batoid fishes, chimaeras and bony fishes. Part 1 (Elopidae to Linophrynidae). FAO, Rome. (Ref. 9862)
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Wikipedia

Spotted eagle ray

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.

Taxonomy[edit]

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.[3][4][5] 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.[4]

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.[6][7][8]

Description and behavior[edit]

Photograph
Close up of the head

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.[9] Their tails are longer than those of other rays and may have 2–6 venomous spines,[4] just behind the pelvic fins. The front half of the long and wing-like pectoral disk has five small gills in its underside.[10]

Mature spotted eagle rays can be up to 5 meters (16 ft) in length; the largest have a wingspan of up to 3 meters (10 ft) and a mass of 230 kilograms (507 lb).[11][12]

Reproduction[edit]

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 she 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.[4]

The spotted eagle ray develops ovoviviparously; the eggs are retained in the female and hatch internally, feeding off a yolk sac until live birth.[4] After a gestation period of one year the mother ray will give birth to a maximum of four pups.[2] When the pups are first born, their discs measure from 170–350 millimeters (6.7–13.8 in) across.[4] The rays mature in 4 to 6 years.[2]

Feeding and diet[edit]

Spotted eagle ray preys mainly upon bivalves, shrimps, crabs, whelks, and other benthic infauna. They feed on mollusks and crustaceans, particularly malacostracans.[13][14] and also upon hermit crabs,[15] shrimp, octopi, and some small fish.[16]

The spotted eagle ray's specialized chevron-shaped tooth structure helps it to crush the mollusks' hard shells.[11][12] 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.[1] These rays have the unique behavior of digging with their snouts in the sand of the ocean. [17] 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.[14]

Behavior[edit]

Two spotted eagle rays swimming at the Okinawa Churaumi Aquarium

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,[17] 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.[18]

Human interaction[edit]

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.[6] There are no target fisheries for the spotted eagle ray, but it is often eaten after being caught unintentionally as bycatch.[6] There have been several reported incidents of spotted eagle rays leaping out of the water onto boats and landing on people.[19][20] Nevertheless spotted eagle rays do not pose a significant threat to humans, as they are shy and generally avoid human contact.[4] 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[edit]

The silvertip shark is a predator of 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.[21][22] 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.[23] Sharks have also been observed to follow female rays during the birthing season, and feed on the newborn pups.[4]
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.[24] External parasites include the monocotylid monogeneans Decacotyle octona,[25] Decacotyle elpora[25] and Thaumatocotyle pseudodasybatis[25][26] on the gills.

Habitat and distribution[edit]

An eagle ray searching the bottom for food

Spotted eagle rays are found globally in tropical regions from the Indo-Pacific area to the oriental part of the Pacific Ocean, and the western Atlantic Ocean.[27]

They are found in shallow coastal water by coral reefs and bays, in depths down to 80 meters (262 ft).[11] Spotted eagle rays are found in warm, temperate, waters worldwide; in the West-Atlantic Ocean, off the coast of North Carolina and down to Florida, in the Gulf Stream, in the Caribbean, and down past the southern part of Brazil. In the West-Pacific Ocean, it can be found from the Red Sea to South Africa and also in northern Japan and Australia.[4] The ray can also be found in the Eastern-Pacific Ocean from 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 reef areas. 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.[4]

Conservation[edit]

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.[3]

References[edit]

  1. ^ a b Summers, Adam (2001). "Aetobatus narinari". Digital Morphology. Retrieved 1 November 2011. 
  2. ^ a b c 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.
  3. ^ a b c Kyne, Ishihara. "Aetobatus narinari". IUCN 2011. Retrieved 23 October 2011. 
  4. ^ a b c d e f g h i j k Bester, Cathleen. "Ichtyology at the Florida Museum of Natural History". Florida Museum of Natural History. Retrieved 21 October 2011. 
  5. ^ Symbolae Antillanae : seu fundamenta florae Indiae Occidenttalis (in German). Berolini : Fratres Borntraeger ; Parisiis : Paul Klincksieck. Retrieved 2011-10-27. 
  6. ^ a b c 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. 
  7. ^ 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. 
  8. ^ Tee-Van 1953, p. 453
  9. ^ Australian Wildlife. "White-Spotted Eagle Ray". Retrieved 29 October 2011. 
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  15. ^ 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. 
  16. ^ SeaWorld; Discovery Cove; Busch Gardens. "Spotted Eagle Ray". Retrieved 1 November 2011. 
  17. ^ a b Silliman 1999, p. 5.
  18. ^ Silliman 1999, pp. 5–6.
  19. ^ CNN. "Woman dies after stingray strikes her". Cable News Network. A Time Warner Company. Retrieved 30 October 2011. 
  20. ^ CNN. "Ray slams woman on boat in Florida Keys". Cable News Network. A Time Warner Company. Retrieved 30 October 2011. 
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  22. ^ "Spotted Eagle Ray, Aetobatus narinari". marinebio.org. Retrieved 9 November 2011. 
  23. ^ Chapman 2002, p. 949.
  24. ^ 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
  25. ^ a b c 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
  26. ^ 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
  27. ^ http://eol.org/pages/218712/details#distribution

Bibliography[edit]

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