Bright orange shark with rare genetic mutation leaves scientists baffled
Scientists spend their entire careers trying to make sense of nature's wildest surprises. But now and then, they encounter something so bizarre it leaves even the experts stumped.
Marine biologist Daniel Arauz Naranjo thought he'd seen it all when it came to sharks. But nothing matched his amazement when he saw images of a bright orange nurse shark (Ginglymostoma cirratum) swimming in the shallow waters off Costa Rica.
"As soon as I saw it, I was like, what? That is crazy," the executive director of Costa Rica's Rescue Center for Endangered Marine Species, told As It Happens host Nil Köksal. "Wow. It's just amazing."
Advert
The discovery happened in August when sport fishermen off Costa Rica's coast spotted an unusual glow in the blue waters.
"We saw an orange glow below the water and I said, 'My God, what is this?'" explained Garvin Watson, owner of the Parismina Domus Dei hotel in Barra del Parismina. "We were all screaming like crazy."
The fishermen, who practice catch-and-release, documented their extraordinary find before setting the shark free and sharing the footage with local scientists. The images were published in the journal Marine Biodiversity last month.
While the colour of nurse sharks can range from tan to dark brown, orange hues are quite unheard of.
According to the International Union for Conservation of Nature, the population of nurse sharks are in decline due to climate change, pollution, habitat destruction and overfishing. They're generally docile around humans and can grow up to 2.4 metres long, making them a familiar sight for divers in warm, shallow waters.
After confirming the authenticity of the footage and verifying it against scientific literature, Naranjo and his team concluded that the creature likely has two rare genetic conditions happening simultaneously.
The first is albinism, which causes a deficiency of melanin (a skin pigment) in both the skin and eyes. The second condition is xanthism which causes animals to appear yellow or golden. This phenomenon has been observed in some reptiles and freshwater fish, but Naranjo notes that this represents the first reported case in a shark.
Shark scientist James Sulikowski from Oregon State University's Big Fish Lab, who wasn't involved in the research, described his fascination with the creature's ability to defy basic survival logic.
"Anytime you find a shark, or other animal, with unique colouration, it is very interesting, especially since typical colour patterns are geared for increased species survival," he wrote. "It makes you wonder how this shark, with such a unique colour pattern, was able to not only survive but thrive in their ocean environment."
Naranjo agrees that the bright orange colouring 'could be a hindrance' to the shark's survival, making it more visible to both predators and prey.
"Who knows? Nobody even noticed that there was an orange shark around, and it managed to survive, and now it's an adult," Naranjo said. "It's a pretty good size, and it was very energetic. So it seems like it's doing very well."
It seems further research is needed to confirm the genetic anomaly.
"We actually don't know why that happened," Naranjo stated, adding that more than anything, he's hoping to see one of these creatures in person.
"Oh man, I would love it," he remarked.