A nurse shark (Ginglymostoma cirratum) exhibiting an unusual orange coloration and white eyes was documented off the coast of Costa Rica in August 2024. This specimen was identified as displaying albino-xanthochromism, a rare genetic condition involving both a lack of dark pigmentation (albinism) and an excess of yellow pigmentation (xanthism).
Observation Details
The shark was encountered by fishers near Tortuguero National Park off the Caribbean coast of Costa Rica on August 10, 2024. It was hooked at a depth of 37 meters (121.4 feet), photographed, measured, and subsequently released unharmed. Photos were later circulated by the eco-tourism company Parismina Domus Day.
Scientific Analysis
Marine biologists, led by Marioxis MacÃas‑Cuyare of the Federal University of Rio Grande in Brazil, investigated the sighting. Their report, published in Marine Biodiversity in August 2025, confirmed the shark's condition based on its intense, uniform yellow to orange coloration and white eyes, noting the absence of the typically black iris.
The shark measured 200 centimeters (6.56 feet) from nose to tail-tip, indicating full maturity, which typically takes over a decade for this species. This suggests the abnormal pigmentation did not impede its survival or development.
Previous Documented Cases
While albino-xanthochromism is rare, it has been observed in other marine species. A speckled hind (Epinephelus drummondhayi) was diagnosed with the condition in 1978 off North Carolina, and a spotted ray (Raja montagui) in the Irish Sea was described with it in 2018. The condition is more frequently documented in birds.
This nurse shark represents the first known instance of a nurse shark displaying both albinism and xanthism simultaneously.
Future Research
Researchers have posed questions regarding the observed condition:
- Whether it is an isolated case.
- If it represents an emerging genetic trend within the regional shark population.
- If it is linked to specific environmental factors in the northern Caribbean of Costa Rica.
- Or if it reflects the species' natural genetic variability and adaptive capacity.
Further investigation into how local environmental conditions influence the expression of such genetic traits has been recommended.