Cownose ray

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For other species of cownose rays, see Rhinoptera.

Cownose ray
Rhinoptera bonasus Brest.jpg
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Order: Myliobatiformes
Family: Myliobatidae
Genus: Rhinoptera
Species: R. bonasus
Binomial name
Rhinoptera bonasus
(Mitchill, 1815)

The cownose ray (Rhinoptera bonasus) is a species of eagle ray found throughout a large part of the western Atlantic and Caribbean, from New England, United States to southern Brazil (East Atlantic populations are now generally considered a separate species, R. marginata). Cownose rays grow rapidly, and male rays often reach about 35 inches (89 cm) in width and weigh 26 pounds (12 kg). Females typically reach 28 inches (71 cm) in width and weigh 36 pounds (16 kg).

Taxonomy[edit]

Rhinoptera bonasus, comes from the Greek derivation of the word parts.

"rhinos"- nose

"pteron"- wing

"bonasos"- bison

Gestation and reproductive behavior[edit]

Cownose rays breed from June through October. A large school of cownose rays gather of varying ages and sexes in shallow waters. A female will swim with the edges of her pectoral fins sticking out of the water, with male cownose rays following her trying to grasp the fins to mate.[1]

The embryo grows within its mother with its wings folded over its body. Initially it is nourished by an egg yolk, although the uterine secretions of the mother nourish it later in its development. The length of gestation is disputed, but it is believed to last between 11 and 12 months and is variable. At full term, the offspring are born live, exiting tail first.

Cownose rays swimming in shallows in the Gulf of Mexico

Lifespan[edit]

Sexual maturity for both males and females is reached around 4 to 5 years of age. In the Gulf of Mexico, females live up to 18 years, and males only live up to 16 years.[2]

Size and appearance[edit]

The cownose ray is 11 to 18 inches (28 to 46 cm) in width at birth. A mature specimen can grow to 45 inches (1.1 m) in width, and weigh 50 pounds (23 kg) or more. There is some controversy over the size that a mature cownose ray can reach. A ray reaching a span of 84 inches (2.1 m) has been recorded.[3]

A cownose ray is typically brown-backed with a whitish or yellowish belly. Although its coloration is not particularly distinctive, its shape is easily recognizable. It has a broad head with wide-set eyes, and a pair of distinctive lobes on its subrostral fin. It also has a set of dental plates designed for crushing clams and oyster shells. When threatened the cownose ray can use the barb at the base of its tail to defend itself from the threat.[1]

A cownose ray has a spine with a toxin, close to the ray's body. This spine has teeth lining its lateral edges, and is coated with a weak venom that causes symptoms similar to that of a bee sting.[3]

Feeding habits[edit]

The cownose ray feeds upon clams, oysters, hard clams and other invertebrates. It uses two modified fins on its front side to produce suction, which allows it to draw food into its mouth, where it crushes its food with its dental plates. Cownose rays typically swim in groups, which allows them to use their synchronized wing flaps to stir up sediment and expose buried clams and oysters.[citation needed]

Migration[edit]

Cownose stingray teeth and mouthparts. Stingray teeth consist of interlocking bars (dental plates) that crush food.

The cownose ray often migrates from the Gulf of Mexico to Trinidad, Venezuela, and Brazil.[3] The Atlantic migration pattern consists of the cownose rays moving north in late Spring and moving south in late Fall.[citation needed]

Migration may be influenced by water temperature and sun orientation, which explains the seasonal migration pattern. Southern migration may be influenced by solar orientation and Northern migration may be influenced by the change in water temperature.[citation needed]

It is unknown whether their migratory behavior is due to feeding or premigratory mating activity.[1]

Habitat[edit]

Cownose rays appear naturally in the Eastern Atlantic Ocean, the Western Atlantic Ocean. Within the Eastern Atlantic Ocean, the cownose ray can often be found in Mauritania, Senegal, and Guinea. In the Western Atlantic Ocean they are located from Southern New England to Northern Florida in the United States, as well as throughout the Gulf of Mexico, Trinidad, Venezuela, and Brazil.[citation needed]

They live in brackish and marine habitats and can be found at depth up to 72 feet (22 m). They are gregarious and migrate extremely long distances, often traveling in schools.[citation needed]

Aquariums[edit]

Cownose rays can be seen in many public aquaria worldwide and are often featured in special 'touch tanks' where visitors can reach into a wide but shallow pool containing the fish which have had their barbs pinched or taken off (they eventually regrow, similar to human nails), making them safe enough to touch. The following aquariums and zoos are known to have a touch tanks featuring cownose rays (alone or with other fish):

USA

Canada

References[edit]

  1. ^ a b c Kittle, Kimberly. "University of Florida". Rhinoptera bonasus. Florida museum of Natural History. 
  2. ^ Puglisi, Melany P. (August 1, 2008). "Smithsonian Marine Station at Fort Pierce". Rhinopera bonasus. 
  3. ^ a b c Ball, Michael (July 16, 2012). "Commercial Fishery Species Guide" (PDF). NOAA Fisheries Service Apex Predator Program. NOAA. 
  4. ^ "Adventure Aquarium - Camden, NJ". www.adventureaquarium.com. Retrieved 23 August 2018. 
  5. ^ "Stingray Touch - Arizona-Sonora Desert Museum". 
  6. ^ "Cownose Ray - Atlantic City Aquarium". 
  7. ^ "SeaTrek Helmet Diving at OdySea Aquarium". Retrieved 23 August 2018. 
  8. ^ http://www.omahazoo.com/family/animal-presentations/default.aspx
  9. ^ writer, Carol Bicak / World-Herald staff. "You can touch a stingray at new exhibit at Omaha's Henry Doorly Zoo & Aquarium". Retrieved 23 August 2018. 
  10. ^ "Petting Zoo - Rooster Cogburn Ostrich Ranch". 
  11. ^ "The San Antonio Aquarium". Retrieved 2018-04-07. 
  12. ^ "Texas State Aquarium". Retrieved 2017-08-16. 
  13. ^ "Cownose Sting Ray". Retrieved 2011-01-09. 
  14. ^ "Quebec Aquarium". Quebec Aquarium. Retrieved 1 August 2017. 
  15. ^ "Ray Bay - Ripley's Aquarium of Canada". Ripley's Aquarium of Canada. Retrieved 1 August 2017. 
  16. ^ "Vancouver Aquarium - Discover Rays". www.vanaqua.org.