A team at an aquarium in Aberdeenshire were recently shocked to discover that some of their resident crabs glow under UV light.
Macduff Marine Aquarium was redressing one of its visitor exhibits, which requires moving some of the animals when they discovered that the edible crabs turned a bright green at spots under the dark lights.
Posting about the fun discovery on their official Facebook page: "#DYK that the edible crab glows under UV light?
"We didn’t and got a surprise when we were moving the crab and happen to take it through our Southern Trench display that had UV lighting!
"How cool is that?!"
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Aquarium Team Supervisor, Theodore Bennison, 28, explained how they come across the fascinating discovery, stating that during the exhibit redress, they need to move animals out to a “temporary accommodation”.
This means they have to clear the tank of rocks and seaweed, cleaning, before repopulating it.
He said: "We have a Southern Trench exhibit in the final stretch of the aquarium, where visitors can learn all about deeper habitats and creatures that never see sunlight, yet thrive in a dark environment, many of which produce their own light source which is known as bioluminescence.
"The crab we were moving through the corridor where the UV lights give off a glow as seen in the photographs. This is called biofluorescence.
"The crabs hard exoskeleton contains molecules that absorb the higher-energy UV light and re-emit it at a lower wavelength, seen as a glowing fluorescent green in this case."
Theodore joked that some of the aquarium's fans have been likening it to the crab in Disney’s Moana (shiny).
He added: "There are also plenty of folk that don’t realise that there is a whole other way to see things outside of the white light spectrum we typically see in, which is why a few years ago we held our Glow event (Nov 2018) to showcase this magical phenomenon.
"Some incredible examples can be seen on the Attenborough’s Life in Colour (available on iPlayer), I highly recommend that anyone who is interested in this secret world of vision in the animal kingdom to give that a watch!"
The crabs themselves are known as the brown or edible crab, but Theodore added that in Doric, they are known wonderfully as " fiery tangs".
He said: "It's really easily identified, it kind of looks like a pasty with claws. Adults can grow to be 25 centimetres wide over the body and weigh up to 3 kg and is the largest crab fishery in Europe.
"It’s a nocturnal predator, feeding on molluscs, like dog whelks, and other crustaceans, and spends the day time partially buried in sand or in rock crevices."
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