A nurse shark caught and released off Costa Rica has stunned scientists with blazing orange skin and white eyes, signaling two rare pigment conditions in one animal.

A new study formally documents the first case of xanthism in this species and notes signs of albinism.

The adult, about 6.6 feet long, was hooked by sport fishers in 2024 and photographed at roughly 120 feet below the surface before being released.

The research team describes the find as the first scientifically verified xanthic nurse shark, recorded near Tortuguero National Park on Costa Rica’s Caribbean coast.

What makes this shark orange

Lead author Marioxis Macías-Cuyare, a doctoral researcher at the Federal University of Rio Grande in Brazil (UFRN), led the analysis of photos and eyewitness details.

The team concluded that the shark’s lack of dark irises and its full body color pattern point to coexisting pigment conditions.

The core trait here is xanthism, an increase in yellow to orange pigmentation that can make animals appear unusually bright. In contrast, albinism involves reduced or absent melanin, often producing very pale skin and light eyes.

When both show up together in the same individual, scientists call it albino-xanthochromism. In this nurse shark, the researchers interpret the combination as intense yellow-orange skin alongside white eyes.

The paper also sets this record in context for elasmobranch fishes, which include sharks and rays. Prior reports in this species have involved other pigment anomalies, but not total xanthism backed by scientific documentation.

Where and how it was found

Fishers encountered the shark off Costa Rica’s east coast and kept it in the water while removing the hook.

They took several clear photographs that allowed specialists to assess eye color and full body pigmentation.

The research notes that the fish swam at about 120 feet, deep enough for filtered light but still within typical nurse shark habitat.

The individual was approximately 200 centimeters long, which places it in adult size for the species.

Xanthism and albinism combination

Xanthism is usually genetic, shaping skin cells that produce yellow to orange pigments. Albinism targets melanin pathways, which affect dark tones in skin and eyes.

The combination is rare but not unheard of in cartilaginous fishes. A 2018 note documented albino-xanthochromism in a ray from the Irish Sea, providing a key precedent.

Researchers are still investigating what flips these pigment switches in sharks. Genetics sits at the center, but environmental stress, temperature, and hormones have been proposed as additional factors.

“We were very surprised and excited when we saw the [xanthism] in the photos. Many factors influence this, such as the environment, but everything remains speculative until the variables that could influence this genetic condition are tested,” said Macías-Cuyare. 

How the orange shark lived so long

Nurse sharks usually wear muted colors, from yellowish tan to gray brown. The Florida Museum species profile describes them as bottom dwelling, often resting in crevices during the day and foraging at night.

That behavior may help a conspicuous animal avoid constant attention. Staying close to the seafloor, tucking into caves, and being mostly nocturnal can reduce exposure to predators.

Feeding habits also matter. Nurse sharks suck up crustaceans, mollusks, and small fish from the bottom, which demands stealth at close range rather than long distance pursuit.

The adult size of this animal suggests its coloration did not prevent it from finding food or shelter. It also signals that mates and rivals tolerated the difference, at least enough for growth to continue.

Orange sharks and new science

This report is the first verified case of a fully xanthic nurse shark. It also provides a documented instance from the Caribbean for a pigment condition rarely recorded in these fishes.

The paper outlines exact measurements and the encounter depth, giving future researchers hard reference points. Details like body length and capture depth can inform hypotheses about visibility, behavior, and survival.

The study also clarifies terminology around pigment anomalies. Using consistent language for xanthism, albinism, and their co-occurrence helps scientists compare notes across species.

Beyond the labels, confirmed records guide conservation and ecology work. Recognizing that such individuals can survive to adulthood challenges simple assumptions about camouflage and fitness.

What comes next

More sampling and standardized photo records would help estimate how often these pigment variants appear. Clear images of eyes and body are especially valuable for sorting albinism, leucism, and xanthism.

Genetic analyses could pinpoint the mutations involved. Linking specific genes to pigment outcomes would turn speculation into testable mechanisms.

Environmental data at capture sites might reveal patterns. If temperature or stress correlates with color anomalies, those links could refine future surveys.

Cooperation between local fishers and scientists is key. Quick photos, careful handling, and timely reporting allow unusual animals to return to the water while still advancing research.

The study is published in Marine Biodiversity.

Image credit: Garvin Watson and Parismina Domus Dei. Parismina Limón Bar, Costa Rica.

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