The first bright orange shark with white eyes was caught and released in the Caribbean, a new study reveals.
The nurse shark (Glynoghtomamoma cirratum) had a mysterious condition called Xanthism or Xanthokroism, which increased yellow pigmentation in the skin. Researchers have documented zancism in several animals, which is the first definitive case of a nurse shark with its characteristics. Sharks also appear to be bleaching, making them even more unusual.
Sports fishermen discovered a shark off the east coast of Costa Rica in 2024. Garvin Watson, owner of the Paris Minas Domus Day Hotel in the village of Paris Minas, swam under the surface, about 6.6 feet (2 meters) long and 120 feet (37 meters).
“We couldn’t believe what we had right in front of us,” Watson told Live Science in an email.
“The orange sharks glowing in the sunlight were not just normal,” he said. “We didn’t know that it would become a global discovery recognized by all biologists in the world.”
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The fishermen photographed the sharks, then removed the hook from their mouths and returned them to the Caribbean. Researchers explained the event and its importance in a new study published in Marine Biodiversity on August 1.
Related: Do sharks make noises? A random discovery may just answer that question
Scientists have documented the zancism of various species, including frogs, birds, and fish. Some animals are usually yellow and orange, but these colors are more prominent in Xanthic individuals of these species.
Nurses’ sharks are usually yellow to grey brown. Studies have sometimes been reported to be characterized by a complete lack of melanin pigmentation in the skin, characterized by this type of skin and iris, but potential Xanthism has never been scientifically documented.
“When we saw it, we were very surprised and excited [xanthism] In the photo, she studied author Marioxis Macias Kujare, a doctoral candidate in biological oceanography at the Federal University of Rio Grande in Brazil, and spoke to Live Science via email.
The researchers spoke with Watson and studied shark photography. They noted that sharks lack the black iris commonly found in the eyes of sharks, and concluded that it was probably albino, as was Xanthic. A 2018 study recorded the status of this combination of ray types (Raja Montagui) found in the Irish Sea.
Researchers are still studying the causes of abnormal pigmentation in sharks. Although these conditions are usually associated with genetics, factors such as environmental stress, high temperatures, and hormonal imbalances can also contribute to different colours.
Macías-Cuyare said that Xanthism is usually genetic, but more research is needed to understand the conditions affecting abnormal pigmentation in sharks.
I’m also interested in the survival of sharks. Animals evolve to be a specific colour to survive better in the environment, so being bright orange when the species is not intended is usually a hindrance. In this case, the shark is an adult and appears to be uncontrollable by its unusual colour.
“Many factors, such as the environment, affect this, but everything remains speculative until the variables that could affect this genetic condition are tested,” Macías-Cuyare said.
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