A rare visitor in the ocean: the first-ever sighting of a white ghost shark was reported off the coast of Albania (photo).

The ocean covers a significant portion of the planet's surface and is home to an immense variety of species. Unfortunately, some of these are currently at risk of extinction, such as the ghost shark (Oxynotus centrina), reports Live Science.

During a recent expedition, scientists captured an exceptionally rare specimen of ghost shark at a depth of about 200 meters off the coast of Sazan Island — an uninhabited military island. The uniqueness of this shark lies in its completely white appearance, and researchers believe it represents the first documented case of leucism in this species.

Leucism is a genetic condition that disrupts melanin production, leading to pigmentation issues. Unlike albinism, where animals completely lack melanin and have red irises, leucistic sharks maintain normal iris pigmentation even if their bodies are entirely white.

According to the lead author of the study, Andrey Galich, director of Sharklab ADRIA in Albania, a leucistic shark can still produce melanin in certain areas, but overall there is a deficiency. Scientists note that the shark found near Sazan Island was leucistic rather than an albino: the animal was pale with almost whitish spots on its tail, but the retinal pigmentation in its eyes appeared normal. The study authors also point out that this case is the first documented instance of leucism in rough-skinned ghost sharks and the first report of a pigmentation disorder in the Oxynotidae family.

Typically, rough-skinned ghost sharks are dark gray-brown or black all over their bodies, with dark spots on their heads and sides that help them blend into their environment. However, photos reveal that this specimen was pale with white-gray spots. Nonetheless, the overall physical health of the shark seemed to be fine.

It is noteworthy that previous studies have indicated that a lack of pigmentation can make an animal more visible to predators and prey, significantly reducing its chances of survival. At the same time, the new research, along with other records of healthy sharks with pigmentation disorders, suggests that such anomalies may not significantly impact the health and life of these predators.

According to Gaich, pigmentation disorders are "exceptionally rare" among sharks — only about 15 cases have been documented among deep-sea species. The scientist explains that leucism is primarily a genetic condition that may arise from anomalies affecting melanin production or distribution.

It is known that disruptions during embryonic development can also lead to abnormal pigmentation patterns. However, researchers acknowledge that further studies are needed to identify other potential causes of color changes. These may include:

• pollution;
• increased temperatures;
• hormonal shifts;
• inbreeding.

Researchers also aim to investigate how human-induced threats, such as pollution and fishing, affect sharks' susceptibility to diseases and other disorders.