Many Minds: The sparkling deep
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Many Minds
The sparkling deep
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The sparkling deep
The sparkling deep
Jun 20, 2026<br>It’s tempting to see bioluminescence<br>as an oddity, one of those rare eccentricities of life on earth.<br>And, on land, maybe that’s true. But our planet is mostly water,<br>and out in the open ocean bioluminescence is utterly commonplace.<br>Creatures of all shapes and sorts sparkle and glow, glitter and<br>pulse. But what are these displays for? Why did they evolve? How<br>did light become the currency of the deep?
My guest today is Dr. Sönke Johnsen. Sönke is a Distinguished<br>Professor of Biology at Duke University, where he and his research<br>group study the visual ecology of the ocean. He’s the author of a<br>number of books: most recently<br>Into the Great Wide Ocean,<br>about life in the pelagic realm, and The Radiant Sea, a photographic tour of<br>bioluminescence and color, written in collaboration with Dr. Steven<br>Haddock.
Here, Sönke and I talk about the<br>open ocean: the most common habitat on our plant, yet one that many<br>people will never experience. We consider the curious distribution<br>of bioluminescence— rare on land, exceptionally prevalent in the<br>ocean, and all but absent in freshwater. We talk about how<br>bioluminescence seems to have evolved—many, many times over in<br>fact. We survey the functions of making light in the deep—from<br>counter-illumination to courtship to revenge. Finally, we consider<br>what Sönke takes to be the biggest remaining puzzle about<br>bioluminescence at sea.
Alright friends, if you’re enjoying<br>Many Minds, we ask (humbly) if you would think about<br>rating us, reviewing us, leaving us a comment, boosting us on<br>social media, or perhaps haranguing your friends—relentlessly—until<br>they give us a listen.
Without further ado, onto my<br>conversation with Dr. Sönke Johnsen. Enjoy!
Notes
3:30 – The scientific<br>report by Dr. Johnsen and colleagues describing the<br>bioluminescent octopus, Stauroteuthis<br>syrtensis.
12:00 – A<br>popular article on the bristlemouth.<br>The article reports a scientist's estimate of “as many as a dozen [bristlemouths] per square meter of<br>ocean.”
15:00 – A<br>recent discussion of the “burglar alarm<br>hypothesis.”
18:00 – The website for the Johnsen Lab at Duke<br>University.
24:00 – A chart and discussion of the depth zones of the<br>ocean.
29:30 – A study by Séverine<br>Martin and Steven Haddock quantifying the<br>prevalence of bioluminescence at different depths. A<br>popular write-up of the same<br>study.
33:00 – A<br>popular article on vertical migration in the ocean, also<br>called “diel vertical migration.” A recent scientific study of the<br>phenomenon.
39:00 – A<br>recent article on the evolution of<br>bioluminescence.
45:00 – For detailed scientific<br>discussion of the physical basis of bioluminescence, fluorescence,<br>and other phenomena we discuss, see Dr. Johnson’s book,<br>The Optics of<br>Life.
52:00 – For previous episodes on the<br>use of sound in the animal kingdom, see here and here. For our previous episode on<br>electroreception and electric ecology (including in marine<br>organisms), see here.
57:00 – For more on the<br>functions of bioluminescence, see<br>here. For a report of a recently<br>discovered function of bioluminescence, see here.
1:03:00 – An<br>article by Dr. Johnsen about the<br>different colors of bioluminescence present in the deep<br>sea.
1:05:00 – A video of ostracod mating displays.
1:08:00 – For our recent episode on<br>cave art, see here.
1:16:00 – For our earlier episode on<br>firefly synchronization, see here.
Recommendations
Website and<br>review article by Steven<br>Haddock
The<br>lab of Todd Oakley
Below the edge of darkness,<br>Edie Widder
Many Minds is a<br>project of the Diverse Intelligences Summer Institute, which is<br>made possible by a generous grant from the John Templeton<br>Foundation to Indiana University. The show is hosted and produced<br>by Kensy Cooperrider, with help from Assistant<br>Producer Urte<br>Laukaityte and with creative support from DISI<br>Directors Erica Cartmill and Jacob Foster. Our artwork is<br>by Ben Oldroyd.
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For updates about the show,<br>visit our website or follow us<br>on Bluesky (@manymindspod.bsky.social).
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Our world is brimming with beings—human, animal, and artificial. We explore how they think, sense, feel, and learn. Conversations and more, every two weeks.
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