Biologist Finds Rare Black Manta Ray Swimming In The Great Barrier Reef

Marine biologist Jactina Shackleton spotted a rare black manta ray swimming near Lady Elliot Island.

The island, situated near the southern end of the Great Barrier Reef, is known for its vast biodiversity. It’s no secret that the area is home to many spectacular things, including some unique manta rays.

Shackleton shared a video of the rare black ray on Instagram, saying, “An incredible shallow water encounter with a feeding Melanistic Manta Ray!”

According to Shackleton, there are only 1370 known melanistic rays in the East Coast populations. IFLScience reported Asia Haines, a member of Project Manta, said there are only 80 known mantas from Lady Elliot Island that are melanistic.

On a worldwide scale, the black rays are even more unique. According to the Marine Megafauna Foundation, manta rays are the only cartilaginous fish in the ocean to display melanism, a black skin pigment from excess melanin.

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The condition affects many animals, including seals, big cats, reptiles, and birds, but it’s much less common in the aquatic realm.

Speaking with IFLScience, Shackleton explained that she’s unsure if the individual ray she spotted was a new melanistic ray or if it’d been recorded before. Melanistic animals can have different spots or patterns which makes them easier to identify, but Shackleton didn’t get a good enough look to tell.

Photo: Wikimedia Commons

It’s unclear why some manta rays exhibit melanism and others don’t, but a 2019 study did rule out some possibilities.

Nobody knows why some rays show this black coloration but a 2019 study did rule out a couple of reasons. Before the study, scientists believed that the color could be a camouflage strategy. However, it was determined that there was no difference in survival rates between black and white mantas, ruling out the camouflage idea.

Photo: flickr/Rickard Zerpe

The research did find that the rates of melanism were largely dependent on location. For example, some areas hosted a population of 7.5% melanistic rays, while others boasted 40%.

You can follow Jacinta Shackleton on Instagram, @jacintashackleton.

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