Last November, Canadian lobsterman Robin Russell was pulling up his catch when he found a unicorn of sorts: Peeking out among the mottled burnt orange and brown was a pastel lobster, sporting a shell of baby blue, pink, and periwinkle.
Initially unsure what to do with the rainbow-clad critter, Russell eventually decided to donate the lobster—dubbed “Lucky”—to the Huntsman Marine Science Centre in Saint Andrews, New Brunswick. But recently, Russell’s Instagram post featuring Lucky’s unusual coloration resurfaced and is making waves online.
Though there aren’t firm stats on the true abundance, the lobster is certainly a rare find. Similarly colored creatures only turn up once every four to five years, says Michael Tlusty, associate professor of sustainability and food solutions at the University of Massachusetts Boston.
Lobster coloring is all thanks to a pigment called astaxanthin. It’s an antioxidant that’s thought to be biologically important. “Humans would call it a ‘superfood,’” notes Tlusty, adding “but I don’t believe in ‘superfoods.’”
The pigment changes color depending on how it’s contorted. In the skin, the pigment is hanging loose and fee, retaining a bright red color. But inside the shell, proteins bind the astaxanthin. “These proteins grab it and twist it, and it actually turns blue,” Tlusty explains. In the outermost layer of shell, the proteins there bend it again, turning it yellow.
Stacking up the reds, blues, and yellows produces the muddy brown coloration of lobsters in the wild. (They don’t actually turn red till you cook them, which denatures the proteins binding the pigment, turning it back to red.)
For the unicorn-colored lobster, it is likely just low in pigment. Though it dons a rainbow of pastel hues, they’re all pretty faint, says Tlusty. The reason behind this lack of color, however, is unclear. The oddball could be the result of either a genetic mutation or its reliance on a low-pigment food source.
Tlusty has actually unintentionally created white lobsters in the past. He spent 20 years working at the New England Aquarium doing lobster research, raising baby lobsters for the work. In an attempt to save money, Tlusty turned to an inexpensive, astaxanthin-free lobster chow.
The lobsters grew perfectly healthy, but they were ghost white.
“A lot of animals eat this and incorporate this color into their pigmentation,” says Tlusty. “Flamingos do it, salmon do it, and it turns out lobsters do it.” But if any of these creatures turn to a pigment-free diet, their coloration fades to white.
It’s possible that Lucky was feasting on the bait that fishermen dumped into the sea, says Tlusty, rather than a more common lobster diet that includes astaxanthin-rich creatures like crabs and shrimp.
A genetic mutation could also be causing the cotton candy coloration, affecting the proteins that bind to the pigments. These mutations can produce some crazy colorings—brilliant blue or yellow lobsters, speckled calicos, or even two-toned split lobsters.
One way to figure out this colorful mystery is to watch what happens to Lucky as it grows. If the reason behind its unusual color is diet, eating pigment-rich foods could make it turn orangey brown the next time it molts.
But if a genetic mutation lies behind the rainbow, then food won’t change its tone—and this crazy-colored critter will remain a unicorn.