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• Interesting Facts
• Taxonomy
• Physical Description
• Distribution
• Habitat
• Diet
• Reproduction
• Song/Voice
• Similar Species
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Overview:

Family: Eagle and manta rays; An oceanic species sometimes found near the coast (Ref. 5217). Forms segregated schools (Ref. 12951). Jumps occasionally, landing with a loud smack, probably as a territorial display. Migrates south in large schools that disappear off northern Florida, USA and are not reported from Caribbean Is.; tagged fish have been recovered in northern South America (Ref. 7251). Population in the Gulf of Mexico migrates clockwise; schools of up to 10,000 rays leave west coast of Florida for Yucatan, Mexico in the fall (Ref. 7251). Ovoviviparous (Ref. 50449).

Interesting Facts:

Taxonomy

Ambiguous Synonyms:

1. Rhinoptera javanica M�ller and Henle, 1841

Unambiguous Synonyms:

1. Raja bonasus Mitchill, 1815
2. Rhinoptera affinis Bleeker, 1863
3. Rhinoptera lalandii Müller and Henle, 1841

Notes:

Name Status: Accepted Name. Synonym: Rhinoptera lalandii. Latest taxonomic scrutiny: October 19, 2000.

Other common names: Spanish: Cara de vaca, Dutch: Echte koeneusrog, Spanish: Gavilan mancha, Spanish: Gavilan manchado, Swedish: Komulerocka, Danish: Konæserokke, Japanese: Kurogane-ushibana-tobi-ei, Finnish: Lehmärausku, Spanish: Mancha, Czech: Maran východoamerický, French: Mourine américaine, Portuguese: Raia-focinho-de-vaca, Portuguese: Raia-sapo, Portuguese: Raia-ticonha, Spanish: Raya gavilán, Portuguese: Ticonha.

The cownose ray was first named Raja bonasus (Mitchill, 1815). This name was changed to the currently valid name Rhinoptera bonasus that same year. The genus name is derived from the Greek "rhinos" meaning nose and "pteron" meaning wing. The species name bonasus is from the Greek "bonasos" meaning bison. Synonyms include Rhinoptera lalandi (Müller and Henle, 1841) and Rhinoptera affinis (Bleeker, 1863) along with a misidentification as Rhinoptera javanica (non Müller and Henle, 1841).

English language common names include cowfish, cownose ray, and skeete. Other common names are cara de vaca (Spanish), chucho (Spanish), echte koeneusrog (Dutch), gavilan mancha/manchado (Spanish), kurogane-ushibana-tobi-ei (Japanese), lehmärausku (Finnish), mancha (Spanish), manta (Spanish), mourine amèricaine (French), raia-focinho-de-vaca (Portuguese), raia-sapo (Portuguese), raya gavilán (Spanish), ray sparrowhawk (Spanish), spot (Spanish), and ticonha (Portuguese).

Physical Description

Family Myliobatidae:

Atlantic, Indian, and Pacific Oceans. Head elevated above disc; jaws powerful with large platelike crushing teeth in several rows in eagle rays; eye and spiracles lateral on head; gill openings about length of eye to much longer; tail much longer than disc; venemous spine(s) present in some; small dorsal fin; pectoral fins reduced or absent opposite the eyes, but with an anterior subdivision that unites below the tip of the snout forming a subrostral lobe in manta rays. Some known for their leaping ability high into the air. Viviparous with 2-6 fully developed young. Plankton-filtering manta rays are among the largest fishes, but harmless.

The family Myliobatidae belongs to the Class Elasmobranchii (sharks and rays) and the Order Rajiformes. It contains 7 genera and 42 species. It may be found in Marine and Brackish environments and is primarily Marine. Members of this family are not used in the aquarium trade. Reproductively, most members of this family are bearers. The main mode of swimming of adult fish in this family is rajiform. Members of this family have been dated back to the Cretaceous period. Etymology of this family name: Greek, myleys, -eos = mill, millstone + Greek, batis, -idos = ray

Species Rhinoptera bonasus:

Distinctive Features: This ray is set apart from all of its relatives by the indented anterior contour of its cartilaginous skull (chondrocranium), with the conspicuously bilobed subrostral fin. The exception to this is the ticon cownose ray (Rhinoptera brasiliensis), which so closely resembles R. bonasus in both appearance and bodily proportions, that they can only be differentiated by their number of teeth. Normally, R. bonasus has only seven series in each jaw while the ticon cownose ray has nine.

The disc is approximately 1.7 times as broad as it is long. The eyes and the spiracles of the cownose ray are located on the sides of their broad head. The main portions of the pectorals arise from the sides of the head, close behind and below the eyes. The outer corners of the pectorals are pointed and become concave toward their posterior margins. The dorsal fin originates approximately opposite the rear ends of the bases of the pelvic fins and is rounded above. The tail, round to oval in cross-section, is moderately stout near the anterior spine, and narrows rearward, tapering to a lash-like tip. The length of the tail, measured from the center of the cloaca, is about twice as long as the body, measured from the cloaca to the front of the head, but can be three times as long on small specimens. There are one or two tail spines. The first spine (posterior spine) is located directly behind the base of the dorsal fin. If present, the second spine (anterior spine) has a free portion that is about half as long as the anterior margin of the pelvic fin. The anterior spine varies in length from very short (tip hardly emerges from skin) to as long as the posterior spine. The spines contain marginal teeth with broad bases and sharp tips that curve rearward at a 45º angle. The number of teeth ranges from 22 to 45. The spine processes toxins and mucous into its ventral grooves, which is produced from spongy venom glands located along the underside of the spine.

Dentition: There are usually 7 series of teeth, on the dental plate, in each jaw that contain up to 11 to 13 rows exposed and functioning simultaneously. The edges of the teeth vary with the median five series being hexagonal, the outermost series being pentagonal, and the supernumerary series being tetragonal.

Denticles: Skin, apart from the tail spines, is smooth at all ages.

Color:

The dorsal surface of the cownose ray is light to dark brown, and can sometimes have a yellowish tint. The ventral surface is white or yellowish white with the outer corners of the pectorals being more or less brownish. Some specimens are marked above and below with many narrow obscure dark lines or bands that radiated outward from the center of the disc. Tail coloration generally follows that of the body.

Size/Age/Growth:

The disc width at birth is about 14 inches (36 cm). There seems to be a considerable variation in the size when maturity is reached, which is independent from geographical influence. A male from the North Carolina waters measured only 26-28 inches (66-71 cm) wide with testes enlarged, whereas a Brazilian male measured 31 inches (79 cm) having the claspers only reach about halfway along the inner margins of the pelvic fins. A female containing embryos measured 24 inches (61 cm). The maximum size that this species ordinarily grows is debated but a disc width of 84 inches (213 cm, male/unsexed) has been recorded.

Images:

Distribution

Range and Population

The distribution of the cownose ray includes the eastern Atlantic Ocean including Mauritania, Senegal, and Guinea. They are also located in the western Atlantic from southern New England to northern Florida (USA) and throughout the Gulf of Mexico, migrating to Trinidad, Venezuela, and Brazil.

Eastern Atlantic: Mauritania, Senegal and Guinea. Western Atlantic: southern New England to northern Florida (USA) and throughout the Gulf of Mexico, migrating to Trinidad, Venezuela, and Brazil^[1].

Habitat

This pelagic species is also sometimes found in inshore waters. For the most part, this species is known for its migrations to different parts of the ocean (oceanodromous). The environments in which they are found include brackish and marine habitats. They are found at depths to 72 feet (22 m). They are gregarious and make long migrations. The cownose ray population is believed to be increasing in numbers. The migration patterns, in the Atlantic, include a northward movement in the late spring and southward movements in the late fall. Southbound migration has been observed to contain larger schools than the northbound migration. Smith and Merriner (1987) believe that the changes in water temperature, coupled with sun orientation, may initiate seasonal mass migration.

They also suggest that the southward migration might be influenced by solar orientation while the northward migration might be influenced by water temperature cooling below 22ºC, but further studies are needed to confirm this. The migratory congregation, thus far, has not been linked to feeding or premigratory mating activity.

Biome

Brackish water, saltwater. Benthopelagic.

Diet

The diet of the cownose ray population in the Chesapeake Bay, Virginia consists primarily of bivalve mollusks. They eat the mollusks by crushing the shells between their terrazo-like tooth plates. Through examination of the cownose rays stomachs and spiral valves, there were large quantities of crushed valves of thin-shelled bivalves, small to moderate amounts of bivalves with intermediate thickness, and only a few small valve fragments of the thick-shelled. It has been suggested that the buccal papillae are instrumental in sorting the shell fragments from the shellfish meats. It has been proposed that cownose rays use a very specific mechanism to obtain deep-burrowing prey. They locate food on the bottom substrate (benthos) through mechano- or electroreceptive detection. Once they suspect prey is there, they employ a combination of stirring motions of the pectorals while sucking/venting both water and sediment out through the gills and away from the area to create a central steep-sided cavity depression. The continued movement of the pectoral fins aids in dispersing the sediments released from the gills and increases the depth of the depression. Eventually, the food is seized and drawn into the mouth. Common prey items include nekton, zoobenthos, finfish, benthos crustaceans, mollusks, bony fish, crabs, lobsters, bivalves, and gastropods.

Reproduction

The breeding period is considered to be June through October. According to observations in July of 2000 by biologists from the NMFS Apex Predators Program, a large school of cownose rays of varying ages and sexes was spotted in the shallows of Delaware Bay. A female cownose ray was seen swimming with the edges of her pectoral fins sticking out of the water. Upon closer observations, up to 6 male cownose rays were following her, trying to grasp the pectoral fins to mate. Occassionally, there would be major splashing as the males tried jumping out of the water to grasp the pectoral fins with their mouths. It is thought that the female's having the pectoral fins out of the water might be mate avoidance behavior.

The exact gestation period is not currently known for the cownose ray. The gestation period is believed to be 11-12 months, although some evidence suggests that cownose rays might have two gestation periods lasting 5-6 months. Development is ovoviviparous, producing eggs that develop within the maternal body and hatch within. The embryos lose the shell capsule in early August. Studies have shown that by the third quarter term, the embryos are upright in the uterus with the rostrum facing forward, pectoral fins folded dorsally, and the tail with the heavily sheathed spine is bent forward along the dorsal side of the disc. The initial nutrition provided to the embryos is from the yolk, which gradually diminishes between August and October. After October, histotroph, a viscid yellowish secretion from the uterus, provides the remaining nutrition. It is assumed that the embryos receive this through the mouth, spiracles, and gill slits.

It is suspected that only one cownose ray embryo is carried to full term but six embryos have been found to make it to full term in one female. Following parturation, females will typically ovulate.

Behavior

Predators:

Some of the predators that are known to prey on cownose ray include cobia (Rachycentron canadum), sandbar shark (Carcharhinus plumbeus), and bull shark (Carcharhinus leucas).

Parasites:

Common bacteria found in cownose ray include Shigella sp. (in intestine) and Serratia liquefaciens (on teeth). Shigella sp. causes inflammatory dysentary (Shigellosis). It is believed that Serratia liquefaciens may be an opportunistic pathogen in this species but has been found to be pathogenic to some salmon and Arctic Char. Cestodes (tapeworms) have been found in cownose rays. Most of these cestodes infect the spiral valve of the cownose ray. The most commonly found cestodes include Rhinoptericola megacantha, Dioecotaenia campbelli, Rhodobothrium paucitesticulare, Eiweria southwelli, and Tylocephalum sp. Benedenella posterocolpa, a monogenetic trematode, has been found on the ventral surface of cownose rays. These trematodes will typically fall off in salinities 28 0/00 or higher.

Song/Voice

Sound types: scrapes. Sound organ: teeth.

Under duress. Sounds only emitted after physical stimulus (prodding), recorded with highpass filter: 150 Hz.
Copyright Holder: Fish, M.P. and W.H. Mowbray (1970). Sounds of Western North Atlantic fishes. A reference file of biological underwater sounds. The John Hopkins Press, Baltimore.

Similar Species

Members of the genus Rhinoptera:

There are approximately 23 species and subspecies in this genus: R. adspersa (Rough Cow-Nose Ray) · R. bonasus (Cow-Nosed Ray) · R. brasiliensis (Brazilian Cow-Nose Ray) · R. braziliensis · R. daviesi · R. dubia · R. javanica (Cownose Ray) · R. jayakari (Oman Cownose Ray) · R. lalandei · R. marginata (Lusitanian Cow-Nose Ray) · R. minimus · R. neglecta (Australian Cow-Nose Ray) · R. marginata · R. percellens · R. polyodon · R. quadrilaba · R. quadriloba · R. raeburni · R. sewelli · R. sherborni · R. steindachneri (Cow-Nosed Ray) · R. studeri · Myliobatis californica

Members of the genus Halosaurus:

There are approximately 16 species and subspecies in this genus: H. attenuatus · H. carinicauda · H. carnicauda · H. guentheri · H. johnsonianus (Halosaur) · H. machrochir · H. nigerrimus · H. ovenii (Halosaur) · H. oweni · H. parvipennis · H. parvipinnis · H. pectoralis (Australian Halosaur) · H. quentheri · H. radiatus · H. ridgwayi · H. sinensis

Bibliography

• Acero, A.P. (1993). Una nueva mirada a los peces comerciales del Caribe Continental Colombiano. An. Inst. Invest. Mar. Punta Buletin 22:129-135.
• Anon. (1994). Atlas pesquero de México. Instituto Nacional de la Pesca. 234 p.
• Cervigón, F., R. Cipriani, W. Fischer, L. Garibaldi, M. Hendrickx, A.J. Lemus, R. Márquez, J.M. Poutiers, G. Robaina and B. Rodriguez (1992). Fichas FAO de identificación de especies para los fines de la pesca. Guía de campo de las especies comerciales ma
• Claro, R. (1994). Características generales de la ictiofauna. p. 55-70. In R. Claro (ed.) Ecología de los peces marinos de Cuba. Instituto de Oceanología Academia de Ciencias de Cuba and Centro de Investigaciones de Quintana Roo.
• Claro, Rodolfo, Kenyon C. Lindeman, and Lynne R. Parenti 2001. Ecology of the Marine Fishes of Cuba. Smithsonian Institution Press. Washington, DC, USA. 253. ISBN: 1-56098-985-8.
• Eschmeyer, William N., ed. 1998. Catalog of Fishes. Special Publication of the Center for Biodiversity Research and Information, no. 1, vol 1-3. California Academy of Sciences. San Francisco, California, USA. 2905. ISBN: 0-940228-47-5.
• Fish, M.P. and W.H. Mowbray (1970). Sounds of Western North Atlantic fishes. A reference file of biological underwater sounds. The John Hopkins Press, Baltimor.
• Gines, H. and F. Cervigón (1967). Exploracion pesquera en las costas de Guayana y Surinam año 1967. Estacíon de Investigaciones Marinas de Margarita. Fundacíon La Salle de Ciencias Naturales, Cont. 29.
• McEachran, J.D. and B. Seret (1990). Rhinopteridae. p. 71-72. In J.C. Quero, J.C. Hureau, C. Karrer, A. Post and L. Saldanha (eds.) Check-list of the fishes of the eastern tropical Atlantic (CLOFETA). JNICT, Lisbon; SEI, Paris; and UNESCO, Paris. Vol.
• McEachran, John D. / Collette, Bruce B., and Grace Klein-MacPhee, eds. 2002. Cownose Rays: Family Rhinopteridae. Bigelow and Schroeder's Fishes of the Gulf of Maine, Third Edition. Smithsonian Institution Press. Washington, DC, USA. 78-80. ISBN: 1-56098-951-3.
• Murdy, Edward O., Ray S. Birdsong, and John A. Musick 1997. Fishes of Chesapeake Bay. Smithsonian Institution Press. Washington, DC, USA. 324. ISBN: 1-56098-638-7.
• 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.
• Robins, Richard C., Reeve M. Bailey, Carl E. Bond, James R. Brooker, Ernest A. Lachner, et al. 1980. A List of Common and Scientific Names of Fishes from the United States and Canada, Fourth Edition. American Fisheries Society Special Publication, no. 12. American Fisheries Society. Bethesda, Maryland, USA. 174.
• Sánchez, A.C. (1997). Listado taxonomico de las especies marinas identificadas en los océanos Pacífico y Atlántico (Caribe) de Nicaragua. Ministerio de Economía y Desarrollo. MEDE PESCA. Managua. 28 pgs.
• Uyeno, T., K. Matsuura and E. Fujii, Editors (1983). Fishes trawled off Suriname and French Guiana. Japan Marine Fishery Resource Research Center, Tokyo, Japan. 519 p.

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Notes

Contributors:

• Brands, S.J. (comp.) 1989-2006. Systema Naturae 2000. The Taxonomicon. Universal Taxonomic Services, Amsterdam, The Netherlands. Accessed October 10, 2006.
• Global Biodiversity Information Facility. Accessed March 01, 2008. http://www.gbif.org Mediated distribution data from 7 providers.
• Kittle, Kimberly. Florida Museum of Natural History
• McEachran, John (from FishBase).

Data Sources:

Accessed through GBIF Data Portal March 01, 2008:

• FishBase: FishBase DiGIR Provider - Philippine Server
• GBIF-Sweden: Fishes (NRM)
• Institute of Marine and Coastal Sciences, Rutgers University: A Biological Survey of the Waters of Woods Hole and Vacinity
• Institute of Marine and Coastal Sciences, Rutgers University: ECNASAP - East Coast North America Strategic Assessment (OBIS Canada)
• Institute of Marine and Coastal Sciences, Rutgers University: iziko South African Museum - Shark Collection
• Institute of Marine and Coastal Sciences, Rutgers University: SEAMAP - marine mammals, birds and turtles
• Museum national d'histoire naturelle: Ichtyologie
• Museum of Comparative Zoology, Harvard University: MCZ Fish Collection
• Royal Ontario Museum: Fish specimens
• UNIBIO, IBUNAM: CNPE/Coleccion Nacional de Peces

Identifiers:

• Integrated Taxonomic Information System (ITIS) Taxonomic Serial Number (TSN): 160985
• Fishbase Species ID: 2584
• Global Biodiversity Information Facility Taxonkey: 110480
• Natural Heritage Network Species Identifier: AFDFG03010
• Zipcode Zoo Species Identifier: 123250

Footnotes:

1. 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.