The spotted eagle ray (''Aetobatus narinari'') is a

cartilaginous fish Chondrichthyes (; ) is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fish'', which have skeleto ...

of the

eagle ray 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. Eagle rays feed on mollusks, and crustaceans, crushing their shells with th ...

family, Aetobatidae. As traditionally recognized, it is found globally in tropical regions, including the

Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

and

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...

s. Recent authorities have restricted it to the Atlantic (including the

Caribbean The Caribbean ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean, mostly overlapping with the West Indies. Bordered by North America to the north, Central America ...

and

Gulf of Mexico The Gulf of Mexico () is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southw ...

) 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 Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a "bridging" form of reproduction between egg-laying oviparity, oviparous and live-bearing viviparity, viviparous reproduction. Ovoviviparous animals possess embryos that develo ...

, the female retaining the eggs then releasing the young as miniature versions of the parent. This ray can be identified by its dark

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...

surface covered in white spots or rings. Near the base of the ray's relatively long tail, just behind the

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

s, are several

venom Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...

ous, barbed stingers. Spotted eagle rays commonly feed on small fish and

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s, 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 Florida Keys are a coral island, coral cay archipelago off the southern coast of Florida, forming the southernmost part of the continental United States. They begin at the southeastern coast of the Florida peninsula, about south of Miami a ...

. The spotted eagle ray is hunted by a wide variety of sharks. The rays are considered

near threatened A near-threatened species is a species which has been Conservation status, categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature (IUCN) as that may be vulnerable to Endangered species, endangerment in the ne ...

on the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological ...

. 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 Great Barrier Reef is the world's largest coral reef system, composed of over 2,900 individual reefs and 900 islands stretching for over over an area of approximately . The reef is located in the Coral Sea, off the coast of Queensland, ...

Taxonomy

The spotted eagle ray was first described by Swedish botanist

Bengt Anders Euphrasén Bengt Anders Euphrasén (born 1756 in the parish of Habo, historical province of Västergötland, Sweden; died 25 December 1796 in Stockholm) was a Swedish botanist. Euphrasén studied at the veterinary school in Skara and then entered Uppsala U ...

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 The Antilles is an archipelago bordered by the Caribbean Sea to the south and west, the Gulf of Mexico to the northwest, and the Atlantic Ocean to the north and east. The Antillean islands are divided into two smaller groupings: the Greater An ...

, and was later classified as ''Stoasodon narinari''. 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 Manta rays are large Batoidea, rays belonging to the genus ''Mobula'' (formerly its own genus ''Manta''). The larger species, ''Giant oceanic manta ray, M. birostris'', reaches in width, while the smaller, ''Reef manta ray, M. alfredi'', reac ...

. Most rays in the family Myliobatidae swim in the open ocean rather than close to the sea floor. 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. The

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

population is ''

Aetobatus ocellatus 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 ...

'' and the East Pacific is ''

Aetobatus laticeps ''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 G ...

''. 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.

Appearance

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 other rays and may have 2–6 venomous spines, behind the pelvic fins. The front of the wing-like

pectoral Pectoral may refer to: * The chest region and anything relating to it. * Pectoral cross, a cross worn on the chest * a decorative, usually jeweled version of a gorget * Pectoral (Ancient Egypt), a type of jewelry worn in ancient Egypt * Pectora ...

disk has five small gills in its underside. Mature spotted eagle rays can be up to in length; the largest spotted eagle rays have a wingspan of up to and a mass of . Aetobatus narinari SI.jpg, Top view Aetobatus narinari SI2.jpg, Bottom view Aetobatus narinari head.jpg, Close up of the head Aetobatus narinari jaws.jpg, Jaws

Reproduction

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 fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

s, which are located on either side of her body. Once he is on her

ventral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

side, the male puts a

clasper In biology, a clasper is a male anatomical structure found in some groups of animals, used in mating. Male cartilaginous fish have claspers formed from the posterior portion of their pelvic fin which serve to channel semen into the female's ...

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 The yolk sac is a membranous wikt:sac, sac attached to an embryo, formed by cells of the hypoblast layer of the bilaminar embryonic disc. This is alternatively called the umbilical vesicle by the Terminologia Embryologica (TE), though ''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 across. The rays mature in 4 to 6 years. Genetic evidence indicates that the spotted eagle ray can undergo consecutive parthenogenesis.

Feeding and diet

Spotted eagle ray preys mainly upon

bivalves Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consis ...

, crabs,

whelk Whelks are any of several carnivorous sea snail species with a swirling, tapered shell. Many are eaten by humans, such as the common whelk of the North Atlantic. Most whelks belong to the family Buccinidae and are known as "true whelks." Othe ...

s and other

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

infauna. They also feed on

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

s (such as the queen conch) and crustaceans, particularly

malacostraca Malacostraca is the second largest of the six classes of pancrustaceans behind insects, containing about 40,000 living species, divided among 16 orders. Its members, the malacostracans, display a great diversity of body forms and include crab ...

ns, as well as echinoderms,

polychaete worm Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are ma ...

s, hermit crabs,

shrimp A shrimp (: shrimp (American English, US) or shrimps (British English, UK)) is a crustacean with an elongated body and a primarily Aquatic locomotion, swimming mode of locomotion – typically Decapods belonging to the Caridea or Dendrobranchi ...

, octopuses, and some small

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

. The spotted eagle ray's specialized chevron-shaped tooth structure helps it to crush the mollusks' hard shells.Spotted Eagle Ray
. Elasmodiver. 3 June 2007. 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.

Behavior

Spotted eagle rays prefer to swim in waters of . Their daily movement is influenced by the

tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables ...

s; 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 The abdomen (colloquially called the gut, belly, tummy, midriff, tucky, or stomach) is the front part of the torso between the thorax (chest) and pelvis in humans and in other vertebrates. The area occupied by the abdomen is called the abdominal ...

and the

s 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

s. 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.

Human interaction

The dorsal spots make the spotted eagle ray an aquarium attraction, although because of its large size it is likely kept only at

public aquarium A public aquarium () or public water zoo is the aquatic counterpart of a zoo, which houses living aquatic animal and aquatic plant, plant specimens for public viewing. Most public aquariums feature tanks larger than those kept by home aquarists, ...

s. There are no target fisheries for the spotted eagle ray, but it is often eaten after being caught unintentionally as

bycatch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...

. 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 tiger shark (''Galeocerdo cuvier'') is a species of ground shark, and the only extant member of the genus '' Galeocerdo'' and family Galeocerdonidae. It is a large apex predator, with females capable of attaining a length of over . Popula ...

, the

lemon shark The lemon shark (''Negaprion brevirostris'') is a species of shark from the family Requiem shark, Carcharhinidae, known for its yellowish skin, which inspires its common name. It is classified as a Vulnerable species by the International Union for ...

, the

bull shark The bull shark (''Carcharhinus leucas''), also known as the Zambezi shark (informally zambi) in Africa and Lake Nicaragua shark in Nicaragua, is a species of requiem shark commonly found worldwide in warm, shallow waters along coasts and in riv ...

, the silver tip shark, and the

great hammerhead shark The great hammerhead (''Sphyrna mokarran'') is the largest species of hammerhead shark, belonging to the family Sphyrnidae, attaining an average length of and reaching a maximum length of . It is found in tropical and warm temperate waters world ...

. 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

s, 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

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

s. Internal parasites include the gnathostomatid

nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...

''Echinocephalus sinensis'' in the spiral intestine. External parasites include the monocotylid

monogenea Monogeneans, members of the class Monogenea, are a group of ectoparasitic flatworms commonly found on the skin, gills, or fins of fish. They have a direct lifecycle and do not require an intermediate host. Adults are hermaphrodites, meaning they ...

ns ''Decacotyle octona'', ''Decacotyle elpora'' and ''Thaumatocotyle pseudodasybatis'' on the

gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...

Distribution and habitat

As traditionally defined, spotted eagle rays are found globally in tropical regions from the

region from the western

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

, the

, and the western

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

. They are found in shallow coastal water by

coral reefs A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. ...

and bays, in depths down to .. Spotted eagle rays are found in warm and temperate waters worldwide. In the western

it is found off the eastern coast of

United States of America The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 states and a federal capital district, Washington, D.C. The 48 contiguo ...

, the

Gulf Stream The Gulf Stream is a warm and swift Atlantic ocean current that originates in the Gulf of Mexico and flows through the Straits of Florida and up the eastern coastline of the United States, then veers east near 36°N latitude (North Carolin ...

, the

, and down past the southern part of

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

. In the

, it is found from the

Red Sea The Red Sea is a sea inlet of the Indian Ocean, lying between Africa and Asia. Its connection to the ocean is in the south, through the Bab-el-Mandeb Strait and the Gulf of Aden. To its north lie the Sinai Peninsula, the Gulf of Aqaba, and th ...

down to

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

and eastward to the

Andaman Sea The Andaman Sea (historically also known as the Burma Sea) is a marginal sea of the northeastern Indian Ocean bounded by the coastlines of Myanmar and Thailand along the Gulf of Martaban and the west side of the Malay Peninsula, and separated f ...

. In the Western

it can be found near Japan and north of Australia. 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 The Gulf of California (), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Vermejo''), is a marginal sea of the Pacific Ocean that separates the Baja California peninsula from ...

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. Within these regions, there are significant variations in

genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinians, Augustinian ...

and

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

.White, W.T., P.R. Last, G.J.P. Naylor, K. Jensen & J.N. Caira (2010). Clarification of Aetobatus ocellatus (Kuhl, 1823) as a valid species, and a comparison with Aetobatus narinari (Euphrasen, 1790) (Rajiformes: Myliobatidae). Pp. 141–164 in: Last, P.R., White, W.T. & Pogonoski, J.J., eds. (2010). Descriptions of new sharks and rays from Borneo. CSIRO Marine and Atmospheric Research Paper no. 32.Richards, V.P., M. Henning, W. Witzell & M.S. Shivji (2009). Species delineation and evolutionary history of the globally distributed spotted eagle ray (Aetobatus narinari). J Hered. 100(3): 273–83.Schluessel, V., Broderick, D., Collin, S.P., Ovenden, J.R. (2010). Evidence for extensive population structure in the white-spotted eagle ray within the Indo-Pacific inferred from mitochondrial gene sequences. Journal of Zoology 281: 46–55. As a consequence, recent authorities have split it into three: This restricts the true spotted eagle ray (''A. narinari'') to the Atlantic, while the

population is the ocellated eagle ray (''A. ocellatus'') and the East Pacific is the Pacific white-spotted eagle ray (''A. laticeps'').White, W.T. (2014): A revised generic arrangement for the eagle ray family Myliobatidae, with definitions for the valid genera. Zootaxa 3860(2): 149–166.

Conservation

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

on the eastern coast of Australia. 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 A breed registry, also known as a herdbook, studbook or register, in animal husbandry, the hobby of animal fancy, is an official list of animals within a specific breed whose parents are known. Animals are usually registered by their breeders w ...

. 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.

References

Bibliography

* * * *

External links

Information and pictures of the spotted eagle ray

White-spotted Eagle Ray, Aetobatus narinari (Euphrasén, 1790)
nbsp;–

Australian Museum The Australian Museum, originally known as the Colonial Museum or Sydney Museum. is a heritage-listed museum at 1 William Street, Sydney, William Street, Sydney central business district, Sydney CBD, New South Wales. It is the oldest natural ...

Species Description of Aetobatus narinari at www.shark-references.com
* {{Authority control

spotted eagle ray 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 author ...

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