Resting quietly on the sea floor, its elegant body flattened and camouflaged, Aetomylaeus bovinus seems to disappear in the shadows. But as it lifts in the water column, sweeping up its wide pectoral fins, its long tail trailing behind, this graceful member of the eagle ray family is hard to forget.
Aetomylaeus bovinus, commonly known as the duck-bill eagle ray or bull ray, is one of at least 34 species of rays found in the Mediterranean Sea. It is a mysterious creature about which little is known. The bull ray’s common name comes from its endearing face with large eyes and a thick, wide snout that looks a bit like a supersized duckbill. Rays, like their close shark relations in the Elasmobranchii subclass, have a cartilaginous skeleton, differentiating them from most other fish which have bony skeletons. It is this light, flexible frame, along with their wide, muscular pectoral fins, that allow them to swim through the water like the raptors of the sea.
Adult bull rays can reach a disc-span of over 100 cm, a length of around 200 cm and a whip-like tail at least as long as their body. The ripple-like stripes on their light-tan backs enhance their graceful appearance and, like human fingerprints, are unique identifiers. They travel through the shallows and the open sea, feeding on a variety of animals including crabs, squid, prawn and mollusks.
Though not a lot is known specifically about the bull ray, details of their fascinating life history can be gleaned from similar rays. For example, rays are well known for their ability to detect and extract mollusks hiding beneath the sand. They do this using a remarkable combination of a specialized electrosensory system and their extended lateral line which is present on both the upper and lower sides and travels out onto the pectoral fins. With these dual detectors, rays can sense both their prey’s weak electric fields and the slight pulses of water that mollusks expel. Once it narrows in on its target, the ray creates suction with its powerful pectoral fins to uncover buried prey. Its plate-like teeth then quickly break through the mollusk shell and its tongue pulls out the edible parts.
While rays are adept predators, they are also a favorite prey species, especially of their large shark cousins. In defense, bull rays use their most notorious feature: their stinger. A strike from a bull ray is certainly painful but luckily uncommon. Bull rays tend to be shy, non-aggressive animals that would rather camouflage or flee; however, if cornered or threatened, they may strike.
Another amazing bull ray fact is how mothers give birth to their young—like rolled up sausages! Unlike most fish, bull rays retain their eggs instead of laying them. The mother carries the young for approximately 6 months, usually giving birth to 3-5 pups. The pups emerge with their pectoral fins wrapped tightly around them, protecting their mother from their stingers.
There are many incredible facts about the bull ray, and there is one troubling fact: bull rays are critically endangered. And they are not alone in this precarious position. 37% of the world’s sharks and rays are in danger of extinction, and the numbers in the Mediterranean are even higher, with 50% of all rays and sharks at risk of extinction. The International Union for Conservation of Nature (IUCN) evaluated 31 elasmonbranchii species, like the bull ray, as Critically Endangered.
With all of that bad news, the plight of rays and sharks can feel overwhelming. The good news is that there are efforts throughout the world, including many in the Mediterranean, to bring these populations back from the brink.
A sampling of the international efforts includes Important Shark and Ray Areas (ISRAS) which focus on a few ray or shark species in a scientifically delineated area. ISRAS attract the attention of policy and decision makers. An exciting project, Sharktrace (also for rays!) is a collaboration led by the organization TRAFFIC which tags and tracks animals from the point of capture, so that individuals and fisheries can advertise legal catches, giving both enforcement agencies and consumers an important way to help rays and sharks. And organizations like World Wildlife Fund (WWF) and Shark and Ray Recovery Initiative (SARRI) have important projects aimed at saving rays and sharks.
Individuals can make a difference by choosing responsible tourist operators that conserve the oceans and benefit local communities. And it is important to avoid capturing rays and sharks while fishing and releasing them safely if caught by accident. Consumers can also help by avoiding ray or shark products, eating sustainably and encouraging businesses to buy sustainably.
Citizen science projects are also a productive way to help rays and sharks. One such program, “Fly with bull rays” at Sharklab-Malta, documents bull rays using a non-invasive photo-identification methodology. Anyone can contribute by joining one of Sharklab-Malta’s citizen science projects or by submitting ray or shark sightings at: https://sharklab-malta.org/0-report-a-sighting/.
Bull rays and their relations provide many benefits to the beautiful beaches and lagoons of the Mediterranean. Along with their roles as both predator and prey, rays act as habitat engineers. In their seafloor search for food, they create micro-habitats for various tiny invertebrates, and bring up nutrients from the sea floor. Rays have been an important part of the Mediterranean since dinosaurs roamed the earth, and in a healthy sea, they will continue to delight visitors and contribute to the ecosystem far into the future.
Written by Rachel Endicott
*Special thanks to SharkLab Malta to provide photos for this article. ©SharkLabMalta
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