Solving A Centuries Old Maritime Mystery

For hundreds of years sailors have told stories about miles of glowing ocean during moonless nights. This phenomenon is known as "milky seas," but the only scientific sample was collected in 1985. So atmospheric scientist Justin Hudson https://graduateschool.colostate.edu/success-stories/justin-hudson/, a PhD candidate at University of Colorado, used accounts spanning 400 years to create a database of milky seas. By also using satellite images to visually confirm the tales, Justin hopes his research brings us one step closer to unraveling this maritime mystery. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave http://plus.npr.org/shortwave. Got a question about a scientific mystery? Let us know at [email protected] mailto:[email protected]. See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

  This message comes from Doppel. Social engineering attacks come in disguise, but Doppel sees through them. The Agentic platform shuts down threats, turns employees into first-line defenders, and more. Learn more at D-O-P-P-E-L dot com.

• 0:16Regina Barber?

  You're listening to Short Wave from NPR.

• 0:23Regina Barber?

  It's 1849. You're on a ship coasting through the middle of the ocean at night. It's calm, glassy waters, and a clear sky full of stars. Then you see off the side of the boat, a glow. Not from another ship or the night sky, but from the surface of the sea. It's coming from the water.

• 0:52Speaker 02

  I cannot permit this opportunity to pass by without describing to you, in the best way I am able, a most extraordinary phenomenon.

• 1:05Regina Barber?

  There's a miles-long swath of glimmering milky water.

• 1:10Speaker 02

  The vessel shortly after entered a vast body of water of the most dazzling brightness and of highly phosphorescent nature. In fact, it looked as if we were sailing over a boundless plain of snow or a sea of quicksilver.

• 1:28Regina Barber?

  This is just one of many written accounts of milky seas that goes back 400 years, according to Justin Hudson, an atmospheric science researcher at Colorado State University. He compiled a database of recent satellite images and all the reports of milky seas he could find from over the years as part of his PhD thesis.

• 1:50Speaker 03

  And a lot of them were ridden off as just, you know, drunks, drunk sailors at the bar trying to impress each other with more, you know, better tall tales than someone else had.

• 2:00Regina Barber?

  Justin's research advisor, Stephen Miller, says it wasn't until about 100 years ago that tales of glowing seas began to be taken more seriously.

• 2:09Speaker 04

  I think in the 1900s, we started receiving more reports from sources such as navies, commerce vessels. These are trustworthy accounts. These aren't, you know, pirates and sailors of yore talking their, you know, spinning their tall tales like Justin was just mentioning.

• 2:30Regina Barber?

  One group definitely not spinning a tall tale, the lone research vessel that accidentally wandered into a milky sea and took the only scientific sample in 1985.

• 2:39Speaker 04

  And the reason for the lack of sampling is simply because milky seas tend to be very remote. And about 70% of the world is covered in ocean and there's just very few people out in any one given spot.

• 2:54Regina Barber?

  So today on the show, maritime lore, deconstructed. How a database of sailor stories and satellite images could help scientists better understand an enduring mystery of the sea. I'm Regina Barber. You're listening to Short Wave, the science podcast from NPR.

• 3:27Speaker 05

  Stay tuned for the following announcements and messages from our sponsors.

• 3:31Speaker 06

  This message comes from Doppel, a lead sponsor of Machine Gods. Social engineering attacks look trustworthy. A routine request, an internal email, a familiar face on a call. But Doppel sees through the disguise. The Agentic platform detects and disrupts attacks, trains employees to recognize deep fakes and deceptions, and investigates every fish to take down the campaign behind it. Doppel, dedicated to outpacing what's next in social engineering. Learn more at doppel.com, D-O-P-P-E-L dot com.

• 4:02Speaker 00

  This message comes from Capella University. That spark you feel? That's your drive for more. Capella University's FlexPath learning format lets you earn your degree at your pace without putting life on pause. Learn more at capella.edu. This message comes from LexisNexis. Legal work demands more from AI. Meet LexisNexis Protege, AI built for how legal teams and professionals actually work. Grounded in authoritative legal content and your work product, Protege brings advanced AI, intelligent agents, and trusted legal capabilities together to help you research, analyze, draft, and verify. Work seamlessly, scale your expertise, produce work you can defend. LexisNexis Protege is AI held to the standard of law.

• 4:48Regina Barber?

  Justin, a lot of the stories like the one we heard at the top of the episode here are from this database that you compiled as part of your PhD. But this is not the first time MLTC database has been made. Many have been made over the last couple centuries, right?

• 5:03Speaker 03

  So about every 40 years, someone seems to learn about milky seas, gets fascinated by the idea, and then builds the best database they could of all the sightings they were able to gather on milky seas. And what has happened to all of those previous databases is that they've all been lost in some way.

• 5:21Regina Barber?

  At sea?

• 5:22Speaker 03

  Not at sea, I hope. The last person to make a database before us, his name was Dr. Peter Herring. And as far as he knows, his database, if it still exists, is just in some unknown archive room in the UK Navy storage somewhere.

• 5:41Regina Barber?

  We say that there's the first scientific sample in 1985, but people did take samples in these historic references. So somebody might have drank it?

• 5:50Speaker 03

  Yeah, there are a few accounts in the database where the best scientific tool someone had to study this was just taking a swig of this strange glowing water out of the ocean and seeing what they could figure out from there. And there is this one account from the early 1800s where the ship's surgeon had heard about this before from sailors in the Middle East. And they had claimed that the water tasted fresh. And so when he encountered one, he immediately took up a bucket and tasted it himself. And he actually complains in the account that it just tastes like normal seawater.

• 6:29Speaker 04

  Yeah, I think that just adding to this, a little bit of irony is that the leading idea for what causes milky seas is bacteria.

• 6:38Regina Barber?

  Right.

• 6:38Speaker 04

  A form of bacteria that will glow upon reaching a critical population. But anyway, the Vibrio bacteria that are thought to be causing milky seas are also of the sort that would cause things like cholera and other, you know, pretty nasty things that can happen inside of our bodies. So the idea of drinking the water may not always be the best advice thing to do.

• 7:02Regina Barber?

  So like, this bacteria, Vibrio harvey, right? And it's, and like you said, like, we think it causes these other things. It's been pretty well studied. Stephen, can you tell me more about this bacteria? And why we think it's the cause of the milky seas?

• 7:16Speaker 04

  Sure. So there are a number of different strains of Luminus bacteria in nature, free living in the water. But at one point in their, their history, they got pooped out from some creature, like a fish. And they like to live in the guts of creatures in some happily ever after scenario for them. But when they're free living in the water, they're also serving the function of breaking down organic material. That's one of the things bacteria do. And when certain bacteria will colonize, say, a speck of organic material, like a piece of algae, their population will increase.

• 8:00Speaker 04

  And at the same time, they are emitting into the water around them a chemical, which they can also detect as being unique. It's kind of like a key into a lock. This chemical is known as an auto-inducer and will actually trigger these bacterial colonies to begin glowing at populations of about 100,000 per cubic centimeter of water. If they get to that critical population, they'll start to glow.

• 8:29Regina Barber?

  Hmm.

• 8:30Speaker 04

  And why would they do that? Well, it gets back to the idea that coming from whence you came. So they make that piece of food glow like a lure in the water, such that it would attract a higher order predator like a fish to come and consume that particle. And guess what? Now they're eaten, but they're exactly where they want to be, back into a gut of a creature.

• 8:50Regina Barber?

  Oh, interesting.

• 8:51Speaker 04

  You know, this is a hypothesis, I want to clarify that. We don't know for sure that this is what's happening, but it's the leading hypothesis.

• 8:58Regina Barber?

  Justin, what's so special about this bacteria? Like, what does this bacteria? How does it glow? And how is that different from the bioluminescence we like have seen in like fireflies or other marine bioluminescence?

• 9:12Speaker 03

  Yeah, so the main way it differs is kind of what Steve touched on, is that it's the function behind why they're bioluminescing. So a firefly, its bioluminescence is sort of like communication of other fireflies. And the more typical bioluminescence you see out in the ocean is caused by this organism called a dinoflagellate. And it glows in response to some kind of shock. Something nudges it, or it gets inside a crashing wave that's on the shore, and it glows as is called a burglar alarm response. As sort of a way to tell whatever is trying to eat it, that like you've been spotted, so you're in danger and you should get away from me.

• 9:56Speaker 03

  Whereas with this Vibrio harvey that we think is behind it, it's glowing actually not to scare away predators, but to attract predators intentionally.

• 10:04Regina Barber?

  So, Justin, like scientists at this point, we're like, we know it's this like luminous bacteria. And you mentioned that there's a story from like the 1700s of Captain Newland, and he said he thought it had to do with some like microscopic organism. How does that make you feel? Like, we're only just like a little bit further than what he thought, right? Like, how much further are we?

• 10:27Speaker 03

  Yeah, I have a couple of different emotions about that, actually. Ben Franklin actually has a letter he wrote to a friend of his in the 1750s where he was complaining how he had carried all these experiments to prove that it was actually electricity and lightning in the ocean causing bioluminescence, but actually he has come to the conclusion that it's just some unknown living being we can't see. Captain Newland, 20 years later, sort of in that same, I guess, scientific discourse, comes the same conclusion about milky seas. And I'm just kind of impressed that they were able to sort of really narrow it down that well back then. And then the fact that we still haven't been able to come that much further since then

• 11:08Speaker 03

  is kind of, it's a little depressing and shows us kind of how hard it is to actually study this.

• 11:14Regina Barber?

  Is that the whole point of this database, Stephen? So that we can finally know a little bit more? Can you tell me like, why this database is so needed?

• 11:22Speaker 04

  We need to find a way to position ourselves to sample very thoroughly, spatially and temporally, what a milky sea is made out of and how it's different from the surrounding waters. So what we're doing is forming a database, then looking for relationships between when milky seas happened and other parameters that we measure all the time, like the nuances of sea surface temperature changes and which directions the winds are blowing and the circulations that happen seasonally and sub-seasonally.

• 11:56Regina Barber?

  And the plan is to pair the database with like, other tools, like satellite images, right? To get a real-time look at things.

• 12:03Speaker 04

  Yeah, that's, that's the goal. We're watching our satellite imagery to see if something forms. And in the in-between part, we've maybe deployed some resources to that area where we're thinking one might form. Finally, the satellite hopefully sees something and we're able to strike at it, realizing that a milky sea may not last more than a few days.

• 12:25Regina Barber?

  Yeah. This is both of your attempt to kind of help with one myth and one mystery, helping with that. Are there any other things that are in the ocean that like, you're interested in learning more about?

• 12:38Speaker 03

  Yeah, I guess, something that has kind of, it's come up in our research on milky seas. There's others like rare forms of bioluminescence that happen out in the middle of the ocean that are both equally as not understood and as well as just, there really isn't any documentation on them.

• 12:59Speaker 03

  And trying to understand, diving into more of those.

• 13:02Regina Barber?

  Wow. What about you, Stephen?

• 13:05Speaker 04

  We think of milky seas as perhaps being this culmination of this communication that's going across these different regimes of our Earth system and leading to this really remarkable kind of seventh natural wonder of the world type display, which visually is really cool to see. But scientifically, it's very, very cool and intriguing as well because we, A, don't understand exactly what conspires to form these things. B, we didn't think it was possible for this many bacteria to blow up overnight in any one place. So just realizing the connection between the various parts of the Earth system is

• 13:46Speaker 04

  just really intriguing and just shows us that there's a lot more to learn about our own planet.

• 13:53Regina Barber?

  Stephen, Justin, thank you so much.

• 13:56Speaker 04

  You're welcome. Thank you for having us.

• 13:58Speaker 03

  Yeah, thank you for having us on.

• 14:01Regina Barber?

  Thank you so much for listening. Make sure you never miss a new episode by following us on whatever podcasting platform you're listening to.

• 14:13Regina Barber?

  This episode was produced by Rachel Carlson. It was edited by Rebecca Ramirez and fact-checked by Tyler Jones. Jimmy Keely was the audio engineer. Special thanks to Martin Patience for the amazing sailor voiceover in the top. Beth Donovan is our senior director and Colin Campbell is our senior vice president of podcasting strategy. I'm Regina Barber. Thank you for listening to Short Wave from NPR.

• 14:53Speaker 05

  Stay tuned for the following announcements and messages from our sponsors.