Stingray, Cownose


Rhinoptera bonasus


Cownose rays have a distinctive bilobed rostrum, giving them their common name. They are diamond-shaped and can reach up to 3 feet from wingtip to wingtip. Their tail is usually twice as long as their body and is rigid. They are light to dark brown/grey in color dorsally, and white in color ventrally.

Family

Rhinopteridae

Order

Rajiformes

Class

Chondrichthyes

Range

Western Atlantic from Southern New England to Florida, Gulf of Mexico, Northern South America, and Western Africa

Habitat

Cownose rays are a pelagic species, which means they inhabit open ocean areas. They can also sometimes be found in inshore areas.

Life Expectancy

13-18 years

Sexual Maturity

There is a considerable variation in size of when sexual maturity is reached.

Diet

In the wild, Cownose rays feed on bottom-dwelling crustaceans, mollusks, and bony fish. In the zoo they are fed a diet of squid, shrimp, and silverside fish.

Status

IUCN - Near Threatened

Behaviors

Cownose rays are a pelagic species, inhabiting open ocean areas. They are migratory, moving south during cold seasons and north during warmer season. Cownose rays are very gregarious, travelling in large schools. They have been observed in schools of up to 10,000 rays. When swimming near the surface of the ocean, their wing tips stick out of the water resembling the dorsal fin of a shark. Cownose rays get their name for their bilobed rostrum, which resembles the nose of a cow. They can grow up to 3 feet wide, with their disc being almost twice as wide as it is long. Their tails are also typically twice as long as their body. The barb, or venomous spine, is located at the base of the body where the tail begins and is only used in self-defense. As with all elasmobranchs, males have a pair of claspers located next to the pelvic fins and are used in reproduction. Breeding season lasts from June to October. The gestation period for a cownose ray is still unknown. Some believe it is 11-12 months, while others believe they have two gestation periods ranging from 5-6 months. They are ovoviviparous and normally only have one pup per pregnancy. At birth, cownose rays measure 14” in disc width. When feeding, cownose rays use electroreceptors and their strong sense of smell to detect prey. They then use their rostrum and wing tips to stir up sand to locate their prey, which is then sucked up with the ray’s mouth. They are equipped with 11-13 rows of grinding plates. These are used to crush the shells of their prey, which they then spit back out. The main predators of cownose rays include large fish such as cobia and a variety of sharks.

Adaptions

Like sharks and other stingrays, Cownose rays have a row of sensory cells called "Ampullae of Lorenzini" used to sense vibrations of prey and predators.

Special Interests

Stingrays, which are cartilaginous fish, do not possess a swim bladder to control buoyancy like bony fish do. Instead they have an oily liver to aid in buoyancy.

Folklore

Conservation

Jacksonville Zoo History

Our Cownose Rays came to the Jacksonville Zoo in 2011.

Exhibit

Stingray Bay