The World's First Orange Shark Is The Result Of Two Rare Conditions

Sharks are some of the most visually distinct species of all animals, from the unforgettably imposing great white with its impressive jaws and unsettling dead eyes, to the hammerhead shark and its unmistakable silhouette. There's also the rare shark species that will outlive us all, which looks like some sort of alien species. But fishermen recently caught what might be the most visually striking shark yet discovered.

In 2024, sports fishers caught a nurse shark (Ginglymostoma cirratum) off the east coast of Costa Rica. But this wasn't your typical example of the species. The 6.6-foot-long fish had bright orange skin and white eyes, making it a one-of-a-kind and a world first discovery.

Much like the incredible rare orange alligators of central Africa, this unusual nurse shark was a complete surprise to not only the fishers who caught and released it but to experts who were yet to encounter such a thing in the wild. Unlike the African alligators, however, the animal's orange skin was not the result of decades of exposure to bat guano. Instead, the fish's unique hue is actually the result of rare skin conditions that have combined to create one of the most strikingly distinctive examples of a nurse shark ever discovered.

The rare orange nurse shark was captured during a sport fishing trip near Tortuguero National Park in 2024. Fishers caught the fish swimming at a depth of roughly 120 feet and were stunned when they hauled it to the surface only to be confronted with what experts described as an "intense yellow-orange pigmentation and white eyes." Researchers published their analysis of the nurse shark photos in a study published in the journal Marine Biodiversity, where they explained that the highly unusual skin color was due to a condition known as xanthochromism, or xanthism. That means this specific nurse shark is not only the first scientifically documented case of total xanthism in the species, but the first ever example of a cartilaginous fish found with the condition in the Caribbean.

Xanthochromism is very rare in marine species in general. In 2021, fish were discovered with the condition in the Arabian Sea, and in 2024, scientists documented the first ever common snook (also known as the sergeant fish) with xanthochromism. There have also been several birds discovered with the skin condition. But this being the first ever nurse shark (which thankfully isn't yet on the list of endangered shark species) to exhibit the condition makes it a truly unique discovery. With xanthochromism, animals experience a loss of darker pigments in their skin, which causes the yellow or orange hue to become much more pronounced. But this particular nurse shark is also thought to have had another condition: albinism.

Due to the fact the creature had white eyes instead of the typical black associated with the species, researchers believe it is likely to have been an albino nurse shark. This condition results in little to no production of another skin pigment called melanin, which can give creatures white hair, skin, and eyes. In this case, the combination of the two conditions resulted in one of the most unique looking animals yet recorded.

Nurse sharks are already unique in that they don't share the grey coloration of most shark species. Instead, they have a yellowish-brown hue and can even be dark brown. But as the researchers who conducted the Marine Biodiversity study noted, since the orange nurse shark appeared to be fully grown, its combination of xanthism and albinism seemed unlikely to hinder the survival of the species. That's significant not only because animals typically evolve with specific colors which help them survive in their environments, but because it increases the likelihood that, if there are more nurse sharks with this unique appearance in the Caribbean Sea, they might well have survived and could be studied in the future.

Though xanthochromism is thought to be genetic, the study notes that there could be other factors at play with this particular nurse shark. Environmental stress and elevated temperatures could have played a role, while the researchers also note that inbreeding and hormonal imbalances might also explain the unique look of this particular specimen. The study authors point out that further research is needed to identify the exact reasons why this nurse shark exhibits such a rare pigmentation.