The Cownose Ray (Rhinoptera bonasus) is a cartilaginous fish from the eagle ray species. It’s native to the western Atlantic Ocean, and in the size department, it’s moderately sized.
The Cownose Ray received its name due to the shape of its head—when observed from overhead, it looks like a cow’s nose.
Just as is the case with eagle rays, Cownose Rays are rarely found not moving whatsoever because they are very active swimmers.
That means it’s even hard to find them lying motionless on the ocean floor, such as the whiptail stingrays, which are closely related.
Although they tend to swim near the surface, people have witnessed them swimming at depths up to 72 feet. Cownose Rays sting only when threatened, and they have mildly venomous spines.
Table of Contents
Characteristics & Appearance
Depending on the geographical location in which they reside, Cownose Rays can vary in size. The females grow larger than the males.
Weight & Length
At birth, the Cownose Ray is anywhere from 11 to 18 inches in width. When fully mature, they can grow to 45 inches in width and weigh about 50 pounds or more.
Conversely, the females will grow to be about feet in width, as the male’s average width is about two and a half feet.
Physical Characteristics & Color
Due to their kite-shaped bodies, Cownose Rays are mistaken for sharks quite often by beach-goers. The Cownose Rays’ fins stick out of the water, mimicking a shark’s dorsal fin.
In general, a Cownose Rays’ body is either brown to olive-colored on the top with scattered spots. Underneath, they are pale with a yellowish or whitish belly.
Even though the color of the Cownose Ray isn’t absolute and distinctive, its shape is certainly recognizable. The Cownose Rays’ eyes are wide-set, and it has a pair of lobes on its subastral fin.
Moreover, the Cownose Ray has dental plates uniquely designed for crushing oysters and clamshells.
When the Cownose Ray feels threatened, it can wield its barbed tail to defend itself. Amazingly, the tail is about two times as long as the body.
The spine of the Cownose Ray has toxins. Furthermore, the spine has teeth that line the lateral edges. A mild toxin coats the barb, which causes symptoms similar to a bee sting.
Lifespan & Reproduction
Male Cownose Rays, on average, live up to 16 years and the females live up to 18 years on average. Cownose Rays are slow to reproduce, and their maturity age is five to seven years of age.
June to October is the Cownose Rays’ breeding season. During this time, male Cownose Rays gather together, where the females swim with their pectoral fins on display and protrude out of the water. The males then try to grab the females’ fins to begin the mating process.
Interestingly, female cownose are ovoviviparous. This means that eggs develop and hatch inside of the mother.
Moreover, the embryos survive off of the energy obtained from yolk sacs. Later down the line in their development, the embryos are then nourished by the uterine secretions from their mother.
The young can mature inside of the mother until they can survive independently, and then she’ll give birth. Typically, females will only give birth to one offspring at a time.
Habitat
You can find Cownose Rays naturally in the Western and Eastern Atlantic Oceans. In the Eastern Atlantic Ocean, you can discover Cownose Rays in Senegal, Guinea, and Mauritania.
On the other hand, they can be found from southern New England to Northern Florida in the United States in the Western Atlantic Ocean.
Not only that, but they can be in the Gulf of Mexico, Venezuela, Brazil, and Trinidad. They are known to live in brackish and marine habitats.
Where Do Cownose Rays Live?
The Cownose Ray lives primarily in estuaries, shallow bays, and coastal areas. They are social creatures and typically travel in groups referred to as schools.
Cownose Rays swim in the same direction. You can find them swimming just beneath the surface of the water.
Food & Diet
Cownose Rays forage for their food. It feeds on various animals, using their plate-like teeth to crush the hard shells of any prey that they come across. They are known to feed in the Chesapeake from May to October.
What Do Cownose Rays Eat?
The Cownose Ray eats oysters, clams, and other invertebrates. They locate their prey by flapping their fins at the bottom of the sea to uncover buried shellfish.
The Cownose Ray has two modified fins on its front side to create suction; this allows it to put such food into its mouth while crushing it with its specialized dental plates.
The Cownose Ray generally eats early during the morning or later in the afternoon, close to evening. These times are when the waves aren’t too boisterous, and the visibility is higher in the afternoon.
The CR has a jaw structure that reflects what they eat: polychaetes, crustaceans, and benthic bivalve mollusks.
Their teeth are similar to cement in hardness, and their jaws are powerful, which allows them to break through a hard shell when feeding.
Though studies have concluded that hard clams and oysters aren’t a large part of their diet, they can go on long stretches of eating just these shellfish.
Some marine experts say Cownose Rays, which travel in schools of up to 10,000, have destroyed shellfish populations.
For anglers targeting these species, there is growing concern about limiting the ray’s ability to consume so many shellfish.
Threats & Predators
The Cownose Ray poses little to no risk to humans unless stepped on or improperly handled. They also do not have many predators, though some exist. Besides this, there are a few environmental factors to consider.
Human Threats
For the time being, commercial fisheries do not target the Cownose Rays, but they can get captured by accident in nets and with hooks.
If anglers do begin catching the CR, it can harm the ray’s population if no regulatory agencies manage this endeavor.
Climate Change & Global Warming
Based on recent studies, experts anticipate that migratory animals will be some of the first species to feel the effects of climate change.
Warming oceans may change their pattern of migration, which can provide insight as to where they begin to travel.
They would not successfully migrate because of severe weather, ocean acidification, sea-level rise, and temperature.
Predators
Cownose Rays are predators that are large enough to defend themselves, but they do have a few predators to stay alert around, such as hammerhead sharks, cobia, bull sharks, and sandbar sharks.
Other Threats
Fishers that believe the Cownose Ray has contributed to shellfish decimation propose fishing for them as a form of population control and preservation for oysters and clams.
Aside from global warming, sharks, and human interaction, Cownose Rays can fend off most predators in the ocean where they reside due to their size.
Conservation Status
The International Union For Conservation of Nature deems Cownose Rays “Near Threatened.” The Cownose Ray population has been down to 45 percent over the last four decades, and it continues to decline. Overfishing is the primary cause of the dip in population.
Fun Facts About Cownose Ray
- The largest Cownose Ray recorded in history was seven feet (2.1 m) long from the end of one wing to the other.
- Cownose Rays are robust swimmers who swim in schools as large as 10,000.
- Cownose Rays have creased head lobes, making their head look like a cow’s nose from above.
- When a Cownose Ray’s fin is visible through the water’s surface, it resembles a shark fin.
- The Cownose Ray can wield its tail as a weapon due to the venomous spine located at the base.
Thank you very much for all the very useful facts about cownose rays! I work at the Saint Louis Aquarium and love how friendly the rays are! And the guest as well love them too!