Researcher Andrey Gaich submerges a shark underwater. (Photo courtesy: Photos by Andrey Gaich, Sharklab ADRIA, research funded by Explorers Club Expedition grant “What Lies in the Depths?!”)
A ghostly great white shark has been spotted off the coast of Albania.
The endangered Pacific silverside shark (Oxynotus centrina) was caught by a commercial trawler near Sazan Island, an uninhabited military island, at a depth of approximately 200 metres (656 feet).
The shark is the first known specimen of its species to have leucism, a genetic disorder that disrupts melanin production and results in reduced pigmentation, scientists report in a new study. Unlike albinism, in which animals lack melanin entirely and have reddish irises, leucistic sharks retain normal iris pigmentation even though they appear completely white.
With leucism, “the individual is still able to produce melanin, but it is deficient in certain areas or throughout the body,” lead study author Andrej Gajic, director of Sharklab ADRIA in Albania, told Live Science in an email. This shark was leucistic, not albino, because “it had a noticeable pallor with almost whitish spots on the tail, but the eyes showed normal retinal pigmentation,” Gajic added. The study, published Oct. 16 in the Journal of Fish Biology, is the first description of leucism in rough sharks and the first record of a pigment disorder in the Oxynotidae family.
Roughneck sharks are typically dark gray-brown or black in color with dark spots on their head and sides, allowing them to blend into their surroundings. In the photos, this specimen was pale in color with whitish-gray spots. Otherwise, its physical condition did not appear to be affected by its unusual coloration.
Close-up of a shark.
“Some studies suggest that the lack of pigmentation may increase the visibility of individuals to both predators and prey, potentially reducing their chances of survival,” Gajic said. This finding, along with other observations of healthy sharks with pigment disorders, suggests that these abnormalities do not significantly negatively impact the ability of deep-sea sharks to feed, avoid predators, or reproduce, he added.
Pigment disorders are “extremely rare” among sharks, with only 15 cases reported among deep-sea species, Gaich said. He clarified that leucism is primarily a genetic disorder that can
Sourse: www.livescience.com
