A Nurse Shark Off Costa Rica Showed Up Looking Like a Traffic Cone

Sport fishers near Tortuguero National Park pulled up a nurse shark in August 2024 that was a vivid, uniform orange with white, irisless eyes. Researchers say the pairing of skin conditions in this shark has no documented precedent.

Albino-xanthochromism is a combination of two rare genetic conditions: albinism, which reduces melanin production, and xanthochromism, which causes unusually yellow or orange pigmentation. Either condition alone is unusual. Both at once, in the same nurse shark, off the Caribbean coast of Costa Rica, is something else entirely.

Researchers confirmed the photos were genuine and that the coloration was a natural, albeit strange, occurrence. The findings, published in the journal Marine Biodiversity, were especially surprising because the condition undermines a crucial survival tactic: camouflage. Nurse sharks are typically light to dark brown, coloring that helps them blend into reefs and rocky habitats. This specimen was approximately the color of a traffic cone.

The shark was full-grown and appeared healthy at capture, suggesting the coloration hasn't hindered its survival.

Researchers are still studying the causes of abnormal pigmentation in sharks. Such conditions are typically linked to genetics, but environmental stress, elevated temperatures and hormonal imbalances may also play a role.

The fishers, who practice catch-and-release, documented the shark and let it go. It is, presumably, still out there.

Read the full story at National Geographic, September 18, 2025

Hot Take: The part where scientists had to assure everyone the photos weren't manipulated tracks. Nature keeps producing findings that look like fakes, so here we all are, running the authentication step first.