A glowing orange nurse shark shocks fishermen off Costa Rica

A bright orange nurse shark stunned fishermen in Costa Rica, marking the first recorded case of xanthochromism in the species and raising new questions about marine genetics.

Off the Caribbean coast of Costa Rica, a group of fishermen stumbled upon a scene that felt ripped from the pages of science fiction. Rising from the water was a bright orange nurse shark, nearly 6.5 feet (2 meters) long, so unusual in color it looked almost painted by hand. Gone was the typical muted gray of its species—this shark glowed as if it belonged to another world.

The encounter took place in August 2024 near Tortuguero National Park, a protected area celebrated for its rich biodiversity. The fishermen wasted no time: they snapped photos and videos that quickly spread across social media, drawing fascination far beyond Costa Rica’s shores. Scientists later confirmed what the images suggested—this was the first documented case of complete xanthochromism in a nurse shark.

A rare genetic twist

Xanthochromism is an extraordinarily rare genetic condition that alters natural pigmentation, replacing standard hues with vivid yellows and oranges. In this shark’s case, the mutation combined with signs of albinism, which explained its ghostly white eyes devoid of an iris. The result was a truly remarkable blend of traits, making the sighting even more extraordinary.

Despite its unusual appearance, researchers noted that the shark had reached full adult size. This means its striking coloration had not hindered survival in the wild—a detail that deepens the mystery. Could such mutations be more common than we think, quietly hidden in the genetic fabric of the species?

Questions beneath the surface

Some experts speculate that the environmental conditions of the Costa Rican Caribbean might play a role in encouraging these pigment variations. If that’s true, then this orange nurse shark may not be entirely alone. Somewhere in those waters, there could be other fish, turtles, or even sharks bearing equally unexpected colors, waiting to be discovered.

For now, the orange nurse shark of Tortuguero remains a singular spectacle—an accidental reminder that the ocean still keeps secrets, and some of them are painted in colors we never imagined.