You've Never Seen a Shark Like This

It looks like a giant goldfish. But what anglers pulled in during a fishing trip near Costa Rica's Tortuguero National Park last year was, as far as we know, one of a kind. The nurse shark, cut loose from a fishing line, is what Gizmodo calls a "rare genetic double whammy"—exhibiting xanthism, an unusual yellow pigmentation often resulting from a lack of red pigmentation, and albinism, a lack of the pigment melanin, resulting in "white eyes, with no visible iris," according to a report published this month in Marine Biodiversity.

While this is the first time xanthism has been observed in cartilaginous fish in the Caribbean, per the Independent, the combination of xanthism and albinism has been observed only once before in a marine creature—a spotted ray taken from the Irish Sea. Both albinism and xanthism are genetic conditions, but researchers say inbreeding, hormonal imbalances, and environmental stresses could've had a hand in creating this golden shark, measured at 6.5 feet long, per IFL Science.

Researchers say it's impressive such a standout shark has been able to survive in the wild as nurse sharks are usually brown, a color that helps them camouflage into the seabed. Otherwise, "xanthism does not directly affect the health of these sharks" and this one "appears to be quite healthy," lead study author Marioxis Macias, an oceanographer at Universidade Federal Do Rio Grande in Brazil, tells Gizmodo.