The specimen was first observed in 2024 during a fishing excursion organized by the tourist company Parismina Domus Dei. “It looked like a huge goldfish with shark teeth”remembers Garvin Watson, local guide. A few photos were taken before the animal was released, then the fishermen passed on their observations to marine scientists.
According to the online media Gizmodo, the animal does indeed belong to the species Ginglymostoma cirratumbetter known as the nurse shark. Very widespread in the Caribbean Sea, this species generally presents nothing exceptional. But this specimen has two extremely rare genetic mutations: xanthism and albinism, a combination called “albino-xanthism”. A phenomenon so unusual that it had only been documented once before in a sea creature.
A genetic and ecological enigma
Fortunately, this double mutation does not compromise the health of the orange shark. “Xanthism does not directly affect the vitality of these animals”confirms Marioxis Macias, oceanographer at the Federal University of Rio Grande (Brazil) and lead author of the study. Based on observations, the animal appears to be in perfect health. Its survival until adulthood, despite its garish color and lack of camouflage, even constitutes an encouraging sign for its chances of longevity.
🇨🇷 Fishermen in Costa Rica caught a rare six-and-a-half-foot orange nurse shark with white eyes, the first known case in the Caribbean showing both xanthism (golden pigmentation) and albinism pic.twitter.com/kEBygyON15
— HOT SPOT (@HotSpotHotSpot) August 19, 2025
In their natural environment, nurse sharks usually display a brownish tint which provides them with effective camouflage on the seabed. Whether this specimen could have grown without this protection questions researchers. They see this as a sign of an unsuspected capacity for adaptation, likely to provide new clues about the evolution of the species in the face of rare mutations.
Scientists are still wondering about the origin of this double mutation. Albinism and xanthism are based on distinct genetic alterations, but their coexistence could result from inbreeding phenomena or environmental factors, such as rising sea temperatures or certain hormonal imbalances.
This discovery reignites debates on the genetic variability and adaptability of nurse sharks in specific habitats. “This orange shark is a fascinating example of the curiosities that nature can offer”enthuses Marioxis Macias.
