A fishing line trembled off the Caribbean coast of Costa Rica, and when the catch broke the surface it wasn’t the usual dusky-brown nurse shark. Instead, sunlight bounced off a glowing, pumpkin-bright body and two ghost-white eyes. “We could not believe what we had in front of our eyes,” recalled Garvin Watson, owner of the local tourism company Parismina Domus Dei, which organizes sport-fishing tours. “That orange shark shining with the sunlight was something out of the ordinary. We did not know that it was going to be a discovery worldwide, recognized by all the biologists of the world.”
This striking six-foot shark carried not one but two genetic surprises. Researchers identified xanthism—also known as xanthochroism—a rare pigmentation quirk that drenches an animal’s skin in yellow-orange tones by suppressing red pigment. Layered on top was albinism, which drained the usual dark color from the eyes and body. The combination, known as albino-xanthochromism, had previously been documented only once before in a ray from the Irish Sea.
From Chance Catch to Global First
Sports fishers first encountered the shark in 2024, about 120 feet below the surface near Tortuguero National Park. They photographed the animal, carefully removed the hook, and released it—unharmed—back into the Caribbean. Scientists later confirmed this was the first scientifically documented xanthic nurse shark, a milestone published in Marine Biodiversity.
Ordinarily, nurse sharks’ muted brown skin helps them vanish against sandy seabeds. Bright orange would seem like a fatal fashion choice, making the animal a glowing target for predators. Yet this shark had grown to adulthood, hinting that survival in the wild can outwit textbook expectations.
Nature’s Color Lab
How did this ocean anomaly come to be? “Further research is needed to explore potential genetic or environmental factors influencing this rare pigmentation anomaly in sharks,” scientists noted. While xanthism is typically linked to genetic mutation, environmental influences—diet, water temperature, even stress—might also play a role.
Xanthism itself is astonishingly rare across the animal kingdom, spotted only sporadically in certain fish, reptiles, birds, and a handful of amphibians. To witness it in a shark—let alone paired with albinism—expands the very map of known marine genetics.
Why One Dazzling Shark Matters
Beyond the thrill of discovery, this encounter sparks profound scientific questions. If a nurse shark can thrive while glowing orange, how rigid are our assumptions about camouflage and survival? Could other hidden color morphs be swimming undetected in the deep?
For ocean lovers and researchers alike, the orange nurse shark is more than a visual wonder. It is a living riddle, reminding us how much of the sea’s story remains unwritten—and how a single flash of color can challenge decades of accepted wisdom.
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