Glow in the dark… Fish?

22nd June 2016

Blog by Aquarium Host Paul Botterill

Recently scientists in the USA made an astounding discovery. Not only are there fish in the ocean which can glow in the dark, it turns out that there are far more of them than we ever thought!

Now, I know what you’re thinking, why on earth would fish need to glow!?!

Well there are actually many different reasons, which may explain why we’ve discovered so many fish that can do it. When animals glow we call it Bioluminescence. Fish usually do this by keeping small glowing bacteria in their bodies. Last week’s paper shows that fish have made this deal with bacteria at least 27 times, meaning there are hundreds of glowing species!

So why are they doing it? Well the most famous bioluminescent fish is the deep sea Anglerfish, which has a special ‘lure’ which glows to entice smaller fish. The smaller fishes think the glowing light is a tasty treat and swim towards it before becoming dinner themselves!

Glowing can help marine creatures avoid being eaten too though. Some plankton will glow so that if any shrimp eat them, the shrimp will glow too, attracting fish-eating shrimp! This is a great way to give the shrimp second thoughts.

The tiny Dwarf Lantern Shark also glows to stop itself from being eaten. Its belly will glow softly to disguise its silhouette against the moonlight from any bigger fish lurking below.

Deep sea Dragonfishes use their bioluminescence to talk to each other, little flashes of light can alert their friends to danger. There’s even been some recent studies that show Dragonfish can warn each other of fishing nets, giving them a chance to escape.

Finally, Ponyfishes have grown elaborate skin flaps so they can flash their bioluminescence and attract a partner.

So why don’t you come and Sleep with the Sharks here at the National Marine Aquarium, and you never know, you could have your own fishy nightlight.

Note: The paper is open source and can be found here –

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