The Spotted Eagle Ray A magnificent underwater creature

My concentration was focused on trying to line up a classic shot of a tiger grouper being cleaned by a juvenile Spanish hogfish, when I heard Jessica’s excited jabbering in her mouthpiece. I quickly raised my head and looked around to see my daughter pointing at a group of vague gliding shapes coming toward us out of the blue. On they came, as I quickly changed my camera settings while staying close to the reef.

We were diving on the North Wall, at a mooring appropriately named Eagle Ray Pass.

Keeping a low profile by a coral buttress, we watched, amazed, as the group of six eagle rays flew toward us with slow strokes of their long pointed wings. Their large heads gave these animals body depth and weight, but what I marveled at was the pattern of spots on the upper side of their disc, or back.

The eagle ray, a beautifully marked member of the family “Myliobatidae”, features a pattern of spots against the dark skin on the upper part of its disc. The lower parts are white and the long tail is black with several spines at the base.

A shovel-shaped snout with a peculiar duck-shaped bill further characterizes this species.

They grow to eight feet across and can weigh up to 500 pounds, making them the largest type of ray encountered in the Cayman Islands on a regular basis. Manta rays grow much larger, but are seldom encountered here. The other two species of rays regularly found around the islands are the famous southern stingray, and the inconspicuous yellow stingray.

Like other large rays, spotted eagle rays are seen swimming singly or in pairs, and sometimes in large schools depending on the time of year. In Grand Cayman we generally see groups of eagle rays, sometimes up to a dozen individuals, in the summer months, and these are possibly breeding aggregations. While we have shot footage of stingrays copulating at the Sandbar, we have not been lucky enough to see eagle rays mating.

They also share with other large rays the habit of leaping from the water during which time they may emit loud croaking sounds. Their duck-billed mouths are used as ploughs to dig up clams, oysters, and other hard bodied burrowing organisms which they crush with their pavement-like teeth.

Spotted eagle rays are circum tropical, and so are encountered by divers all around the world. Although they migrate across open water, their abundance in protected situations indicates that they are predominantly a coastal species. They do penetrate river mouths but are generally found in lagoons, shallow sand flats, and around coral reefs.

As large adults, they spend a lot of daylight hours gliding along the drop-offs in Grand Cayman, just out in the deep water, creating wonderful photo opportunities for divers like us. Jessica and I got some wonderful shots as the school of six rays kept going and passed us before being enveloped in the blue distance.

When I was working on my PhD thesis in Kingston Harbour, Jamaica, I regularly encountered juvenile eagle rays of eight to twelve inches. They are called “sea fowl” in Jamaica, because their spots resemble those of the spotted guinea fowl. They are also called leopard rays in some Caribbean islands. As juveniles their tails are three times their disc length, but otherwise they are perfectly formed miniatures of their parents at birth.

They shelter from predators in the shallow mangrove-lined lagoons and bays, before venturing out on the shallow sea grass beds to look for food at night.

Their predators include all species of coastal sharks, such as the great hammerhead, bull shark, tiger shark, and Caribbean reef shark. A few years ago, Demian Chapman, a post graduate student at the Guy Harvey Research Institute, witnessed and photographed a great hammerhead chase down and catch a spotted eagle ray near South Bimini in the Bahamas. Demian said the large shark chased the ray into shallow water and pinned the ray to the substrate with the ventral surface of one of its hammers or cephalofoil.

In a move called “pin and pivot”, the shark used a twisting motion of its body and pivoted, its head remaining atop the ray. In this case the shark pivoted about 90 degrees, and engulfed the ray’s head in its jaws, picking it up off the bottom and swimming away with its catch. One wonders if the battery of large spines at the base of an eagle ray’s tail is any defense against a powerful bull, tiger or hammerhead shark.

There is no widespread commercial use for this species as food in the Caribbean, and dive operators consider these magnificent creatures to be valuable attractions, enhancing the client’s underwater experience.

While eagle rays’ distribution is global, they are not common. Their flesh is dark red but edible, as their pectoral muscles are full of myoglobin, which gives them the swimming power we see and admire as they fly along the drop-off. 

In May 2013 spotted eagle rays were protected from being caught by a new law that protects all rays in Cayman waters. Under the new National Conservation Bill, sharks are also now protected.

It is our collective responsibility to conserve the marine environment and maintain the biodiversity of our planet. Fish responsibly, dive safely!

About Guy 

 

 

 

Eatle_Ray_sm.jpg