Govind TekaleImagine seeing a roughly two-metre nurse shark underwater — except instead of the familiar brown-grey colouring, the animal is vivid orange with pale eyes.
In August 2024, a fisherman in Costa Rica caught and released a nurse shark with unusual pigmentation during a sport-fishing trip. Researchers subsequently studied photographs and measurements, and the discovery became the first scientifically documented case of xanthism in a nurse shark species.
What xanthism means
Normally, nurse sharks display brown or grey-brown skin. This animal had intense yellow-orange pigmentation across its entire body. The distinction matters. Xanthism is associated with unusually high levels of yellow pigmentation. Albinism involves a loss or absence of melanin pigmentation. This particular shark’s white eyes revealed the albinistic component. Its vivid orange skin revealed the xanthic component. The combination is what made the finding unusual.
The survival puzzle
Nurse sharks are bottom-dwelling, nocturnal predators that hunt benthic invertebrates — crabs, shrimp, small fish. Their normal brown-grey coloration lets them blend into sand, reef structures and mangrove roots on the ocean floor. Camouflage is survival for a bottom-feeder.
This orange shark had no camouflage. Its vivid colouring would make it conspicuous to prey and to other marine animals. Yet the animal was an adult, healthy enough to be captured and released by researchers Garvin Watson and Juan Pablo Solano. The shark’s survival to adulthood raises questions about how much camouflage contributes to survival in this species and whether other sensory systems play a larger role in hunting behaviour.
First documented, not first ever
The scientific paper describes this as the first documented xanthic nurse shark, and the first recorded case of xanthism in any cartilaginous fish (sharks, rays, skates) in the Caribbean. “First documented” is crucial. The condition may have occurred in nurse sharks before; we simply had no scientific record of it until this discovery.
A June 2026 follow-up from University of Texas Marine Science Institute discussed the animal again, describing it as tangerine-coloured and noting that researchers believe the pigmentation involved both albinism and xanthism working together.
What scientists still don’t know
The genetic cause of the dual pigmentation anomaly remains unclear. Whether the condition affects the shark’s sensory abilities, lifespan, or reproductive fitness is unknown.
What we do know: a 2-metre orange shark survived in Caribbean waters, was observed and measured, and added a previously undocumented pigmentation record for nurse sharks.
