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The Glow Below

October 31, 2025

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5 min read

The Glow Below

In the 1980s, oceanographer Edie Witter was a grad student on a research ship, plunging her numb hand into icy water to pull out deep-sea creatures that had been brought up alive for the first time. One of the first animals she grabbed was a bright red shrimp about the size of a hamster, squirting neon blue light from tubes on either side of its mouth. "It dripped between my fingers back into the tub," she recalls. "It was cold light and it was brilliantly blue." That moment changed her life. At the time, she says, you could pick up a marine biology textbook and find no mention of bioluminescence. "It's not that they didn't know about it," she says. "It just didn't think it was very important." Edie Witter has spent the last 40 years proving otherwise.

A World of Living Light

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What you'll learn

  • 1 (01:27) **Opening: The Call of the Deep** - Molly Webster introduces deep-sea explorer Edie Witter, who recounts her first encounter with bioluminescence as a grad student in the 1980s, pulling a glowing shrimp from the ocean.
  • 2 (05:16) **First Dive: A Fireworks Display** - Edie describes her first open-ocean dive in the "Wasp" suit, a one-person submersible, descending to 800 feet.
  • 3 (09:17) **The Many Uses of Living Light** - Edie catalogs the diverse survival strategies bioluminescence enables in the deep sea.
  • 4 (11:41) **Gothic Light Organs: The Bearded Sea Devil** - A deep dive into the bizarre anatomy of a specific anglerfish that uses two completely different light systems on its head.
  • 5 (17:58) **The Origin of Glow: A UV Solution** - Edie explains the evolutionary puzzle of how bioluminescence could have started when a single bacterium's light is invisible.
  • 6 (20:26) **The Flashback Phenomenon** - Edie describes a major discovery while piloting the submersible Deep Rover: the ocean flashes back at her.
  • 7 (23:58) **Becoming Part of the Dance** - Edie theorizes that the bacteria glow to be eaten, and that her sub's thruster or light makes her a participant in the deep sea's light-based communication.

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Show Notes

A call to oceanographer Edie Widder about a fish with a very odd immune system quickly becomes something else: a dive into the deep sea, into a world of brilliant light. But down there, the light doesn’t behave like light -- it sparkles and glows, but also drips, squirts, and dribbles. Today, find out how creatures make the light and how they use it, from hunting and hiding to maybe even … talking. And hear about a series of mysterious moments where Edie goes from studying the creatures to becoming one of them. 

EPISODE CREDITS: 
Hosted by - Molly Webster
Reported by - Molly Webster
Produced by - Maria Paz Gutierrez
with help from - Molly Webster
Fact-checking by - Diane A. Kelly

LATERAL CUTS (Other Radiolab episodes you may like):
Octomom - https://radiolab.org/podcast/octomom
The Darkest Dark - https://radiolab.org/podcast/the-darkest-dark

EPISODE CITATIONS:
Documentary - 
Coming soon, there’ll be a new doc about Edie’s life and work studying bioluminescence in deep sea creatures. According to Edie, “A Life Illuminated”, contains some of the best deep sea bioluminescence footage ever recorded. It’s from our friends at Sandbox Films, and director Tasha Van Zandt.
https://www.sandboxfilms.org/films/a-life-illuminated/

Books - 
Edie Widder wrote a memoir! Go read, “Below the Edge of Darkness: A Memoir of Exploring Light and Life in the Deep Sea”.https://www.penguinrandomhouse.com/books/564185/below-the-edge-of-darkness-by-edith-widder-phd/

Videos - 
It’s not in the episode, but a few years back, Edie’s fame reached new heights when she captured footage of a never-before-seen Giant Squid … here’s the story, and video.
https://www.youtube.com/watch?v=krDdv9KLmuM
 

Articles - 
A look at some glowing shrimps.
https://zpr.io/3jyHWi7VFBw5

A photo gallery of different types of deep sea glow, from different types of deep sea creatures, including one of counterillumination, which Edie talks about in the episode.
https://zpr.io/hdFFsArGjhau
 

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