Squid glow in the dark to help communicate

Anyone who knows me, knows I’m pretty obsessed with bioluminescence – the light produced by creatures that glow in the dark. On a trip to the US last year, I visited New York just to spend a few days hanging out with the fireflies in Brooklyn’s Prospect Park.

Every evening I sat on the grass mesmerised by their flashing green lights. All around me people hurried about their business without giving the little beetles a second thought.

I’ve been immensely privileged to turn my obsession into a career: making bacteria glow to study how nasty bacteria make us sick and to find new medicines.

While I find scientific research an immensely rewarding career, it is also incredibly frustrating when experiments don’t work.

As a PhD student, when none of my experiments were going as planned, I’d sit in the dark room with a flask of my glowing bacteria. I’d swirl the liquid around gently, watching the beautiful blue light come and go.

The chemical reaction the bacteria use to make that light needs oxygen. With every gentle shake of the flask, the bacteria would take in a gulp of air and, for a few moments, glow a little brighter. Even 20 years later, just thinking about that calms me down.

So it seemed fitting then, that as I sat in my Covid-19 lockdown bubble this morning, I got an email alert about glowing squid.

Researchers from Stanford University and the Monterey Bay Aquarium Research Institute (MBARI) have been studying how Humboldt squid, Dosidicus gigas, use their bodies as a sort of glowing billboard to communicate with each other.

These 1.5-metre-long predators live in the deep cold waters of the Pacific Ocean.

Using high-definition video cameras on unmanned, robotic submarines Benjamin Burford and Bruce Robison were able to watch how individual squid behaved when they were feeding and when they were just swimming around.

They saw the squid put on incredible flashing and flickering displays as they fed alongside other squid of the same species.

Perhaps it was their way of telling each other ‘‘hey, that fish is mine’’. Or maybe, ‘‘stay in your bubble’’.

The squid put on incredible flashing and flickering displays as they fed alongside other squid of the same species.