Invisible Nature: The Glowing Squid

Instead of hiding in the dark, the Hawaiian bobtail squid cruises through moonlit waters—and hides its own shadow.

The Hawaiian bobtail squid (Euprymna scolopes) spends its days buried in sand and its nights stalking prey in the shallow waters off the coast of Hawaii. Just because the squid hunts at night, however, doesn’t mean that it relies on the cover of darkness. Its strategy is quite the opposite, in fact. This tiny speckled squid (an adult is about the size of your thumb) can cruise above its prey without casting a shadow—even on a moonlight night—thanks to its relationship with a bacterial partner, Vibrio fischeri. Juvenile bobtail squid are born without the bacteria; they recruit V. fischeri from the surrounding ocean water and then house the hitchhikers in a specialized light organ. In exchange for room and board, the bacteria help the squid hide at night—by glowing. The light they emit blots out the squid’s shadow, letting it sneak up on prey, and hide from predators.

Annette Heist, Ruth Lichtman, and Flora Lichtman

Annette Heist is a science writer, radio producer, and a registered nurse working in behavioral health. Ruth Lichtman is a multi-disciplinary visual artist and filmmaker whose work has been featured on The New York Times, The Atlantic, Aeon, and The Huffington Post. Flora Lichtman is a science journalist who has worked for “Bill Nye Saves the World” on Netflix, The New York Times, and Science Friday. She hosts a podcast called Every Little Thing.

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