A vast whale graveyard + Zombie sea cucumbers

[MUSIC PLAYING] FLORA LICHTMAN: Hey, it’s Flora, and you’re listening to Science Friday. Researchers discovered a vast whale necropolis deep in the Indian Ocean, a.k.a. a massive undersea graveyard for deceased whales. Stretching around 745 miles, it contains whale remains dating back over 5 million years. And it’s not a dead-end, quiet place. There are at least five active whale fall sites in the zone, teeming with life. Joining me now to talk about it is Nick Pyenson. He studies fossil whales and excavated an ancient whale graveyard in Chile’s Atacama Desert. Hey, Nick, thanks for being here.

NICK PYENSON: Thank you so much. Really happy to be here.

FLORA LICHTMAN: OK, you were not involved with this new find, but was it big news in your world?

NICK PYENSON: Oh, yeah. I was so happy to see this paper. And it kind of blew my mind for a bit. And there’s several reasons for that. One is the incredible logistics it takes to get the scientific infrastructure out into the ocean to find this kind of site. They conducted at least 32 dives to go document this site, and I half-expected to hear about these kinds of discoveries because we about these whale superhighways that are cross-cut the world’s oceans. Your chances of seeing a whale in the ocean is not equal everywhere. Whales seem to prefer certain corridors.

FLORA LICHTMAN: I didn’t know that. There are whale superhighways.

NICK PYENSON: Yeah, and that’s a result of decades and decades of work, of tracking whales– where they go to feed, where they go to eat, to mate– all through the course of maybe a migration cycle. And you kind of expect to find the remains of those superhighways on the sea floor, underneath. So there should be places around the world that you expect to find the remains of whales. And I think this is probably one of them.

The other thing that’s really spectacular about this finding is just the extent. I mean, we’re talking about an area that, in one linear distance, might measure the same distance from New York to Chicago. So imagine driving from New York to Chicago, and there were just whale bones littered all across the highway. That’s a bit mind-bending, I think.

FLORA LICHTMAN: Can you help me picture it?

NICK PYENSON: Yeah, so they found two different categories of whale sites. They found the remains of fossil whales, and then they also found a whale fall that is kind of a whole ecosystem that colonizes on the carcass of the remains from a living whale. And from that group, they found baleen whales and a lot of other beaked whales. Most of the fossil sites seem to just be beaked whales. I think that the experience the researchers must have had was just coming across whale skeleton after whale skeleton as they cruised in their submersible along the seafloor. And that’s why the researchers said, this is a mega site. This is a density that we have not seen anywhere else in the world.

FLORA LICHTMAN: This sounds like this is one of these whale superhighways, but is it also like the Bermuda Triangle? Why are they dying here?

NICK PYENSON: Right. It seems like that there is a preponderance of deathly remains of whales. And that’s why I think the researchers use the word “necropolis” to describe the mega site. And, and I kind of went back and forth about in my head whether necropolis was the right word because necropolis implies human intent of concentrating remains. It’s also– whale necropolis is also a fantastic band name. So that’s out there for somebody to grab. But what we’re really seeing is that it’s an exposure on the seafloor that has skeletal remains that accumulate over hundreds of thousands of years.

I mean, think of it this way is that some of those bones on the seafloor have been exposed, sitting there for the entirety of our own evolutionary history. So the geologic time span of our own species is encompassed by those lonely set of bones on the seafloor. So if you have enough time, then you can accumulate a lot of skeletal material. You can think of it like a cave site or like a tar pit. These are places that end up recording a lot of remains from the outside environment, including the bones of animals that happen to live nearby or even in the cave itself, or fall into a tar pit. And these will accumulate over a long period of time.

And clearly, this is still happening today. That’s what those active whale fall sites tell us, is that whales are still falling to the seafloor and being colonized and forming entire ecosystems that are supported by the nutrients from their bones.

FLORA LICHTMAN: Where does this find rank on a paleontologist’s bucket list?

NICK PYENSON: I have such a long bucket list of places I want to go and fossils I would love to collect. I think this created a new category on my bucket list because I didn’t realize that we would have a chance of documenting the remains of these super highways on the sea floor.

FLORA LICHTMAN: And it seems like because whale fall sites bring a lot of other animals to the yard, is it possible that there’s lots of other cool fossils–

NICK PYENSON: Oh, sure.

FLORA LICHTMAN: –to find, too?

NICK PYENSON: I mean, I bet there are shark teeth down there. I bet there are parts of smaller whales that are just not easily seen. So you’re collecting what you can see from a submersible, and that tends to be the bigger stuff. The researchers report a preponderance of beaked whales, and beaked whales are among the most species-rich group of whales on the planet, and we hardly anything about them. And I think that’s one of the big messages I take away, is that if you’re talking about being on the edge of scientific discovery, oh my gosh, the seafloor is where it’s at. You will find more surprises just like this one. But it takes a bit of effort and knowing where to look.

FLORA LICHTMAN: Ah, that’s the perfect place to land. Dr. Nick Pyenson is curator of fossil marine mammals at the Smithsonian National Museum of Natural History. Nick, thanks so much for talking with me today.

NICK PYENSON: So happy to be here, Flora.

FLORA LICHTMAN: After the break, you don’t need a graveyard if you never die. Stay with us.

[MUSIC PLAYING]

IRA FLATOW: Imagine if you were to lose a body part– let’s say a toe. You’d hurry to get medical care. But that lost toe would eventually shrivel up and decompose. But researchers have found that in some species of sea cucumbers, that lost body part may be a tentacle or a tube foot– that part can keep on living without the rest of the organism. So far, they’ve observed what they are calling zombie sea cucumber parts, living for at least three years. Pretty wild stuff.

Joining me now to talk about it are Rachel Sipler, a senior research scientist at the Bigelow Laboratory that’s in East Boothbay, Maine, and Sara Jobson, a PhD student at the Memorial University of Newfoundland in St. John’s, Canada, two authors on a recently-published report on this phenomenon. Welcome to Science Friday.

RACHEL SIPLER: Thank you for having us.

SARA JOBSON: Thanks for having us.

IRA FLATOW: Yeah, you’re quite welcome. Let me get right into this because it sounds really weird. It looks like this discovery was sort of serendipity made by keen observation, not expected. Take me through the discovery, please.

RACHEL SIPLER: Yeah, so I have to first give credit to one of the collaborators on the paper, [? Emmy ?]Montgomery, who was a graduate student just before Sara. And [? Emmy ?] was the one to first say, why are there still feet in this space? The feet became detached from the organism, and they stayed in their general state for extended periods of times– days, weeks, months. And really, they shouldn’t. So in marine systems, they should degrade, bacteria should attack them, and they should pretty much disappear. That didn’t happen. So when [? Emmy ?] Montgomery discovered that these feet were still here, we wanted to understand why.

IRA FLATOW: And why did they not disappear?

RACHEL SIPLER: Yeah, that’s part of the question that we’re still trying to discover is what factors within the tube feet and the organism themselves allow them to persist under pretty significant bacterial pressure.

IRA FLATOW: Sara, do these body parts do anything? Or are they just sitting there on the glass or the side of the tank?

SARA JOBSON: So the tube feet are pretty stationary. They don’t move around, but they do restructure and reform a little bit. The tentacles, on the other hand, when they were healing and surviving in natural seawater, they were actually continuing to move around and respond to their natural environment. It almost looked kind of like they were trying to continue feeding. And when we would poke them or move the water around them, then they would retract into themselves as though they were responding to maybe predator pressure or something like that.

So it seemed as though there was still a bit of neural function going on in these tentacles, almost a little bit like Thing from The Addams Family.

IRA FLATOW: [LAUGHS]. That’s why you’re calling them zombie parts.

SARA JOBSON: Yes, they kind of straddle that line between what is alive and what is dead.

IRA FLATOW: Well, let’s get into that a little bit more. Why would they not be alive? Why would they not be dead?

SARA JOBSON: Oh, man. I think this opens up a lot of questions that still need to be explored. And it honestly took us in a lot of maybe philosophical directions because they kind of defy some of those boundaries that we’ve put on why organisms want to be alive or the evolutionary advantage. The fact that these organisms are persisting, they’re demonstrating some of the key fundamental processes that keep tissues alive, but they don’t reproduce, which is something we expect to see in living organisms. And so they exist in the gray zone a little bit.

RACHEL SIPLER: Yeah, I think that the understanding that we can gain from this is pretty impressive. I mean, think about when you have an organ transplant or something like that, you’re rushing so that the tissue doesn’t die and nothing happens. If we can learn more about how a tissue is able to survive outside of the organism, maybe we can understand how to preserve it for longer for our benefit.

IRA FLATOW: How are these body parts, so to speak, able to fight off being eaten, fight off bacteria, microorganisms in the ocean? I mean, do they have an immune system to fight off infection?

IRA FLATOW: Yes, so one of the things that we looked at in this study was the presence of their immune cells, which in sea cucumbers are called coelomocytes. And so we used histology to look at the internal organization of their tissues. And we saw that their immune cells were still there, and they were actually migrating through the tissues to specific sites. So early on during the wound healing and regeneration, the immune cells migrated to the wound site and seem to be helping with cleaning, degrading tissues, and possibly preventing invasion by bacteria and things like that.

IRA FLATOW: Now I know that sea cucumbers have mouths and stomachs. How does a zombie foot or a tentacle part stay alive while not eating?

SARA JOBSON: Well, that was one of our questions. So we actually added some nutrients in the form of amino acids. So we added supplemental amounts of that to the water. And we found that the podia, or the tube feet, were actually able to take up those nutrients without needing a digestive tract or mouth.

IRA FLATOW: So would you say that it’s still growing? Can you see it expanding and growing, Sara?

SARA JOBSON: So they did grow in size a little bit, but I would say the most striking change was in their appearance. So they went from looking, as you would expect a tube foot to look, if you what those look like, to reforming into a spherical shape. It looked almost like something from outer space after a couple of years because they became perfectly circular and almost transparent around the outer edge. And all of the red pigmentation that the sea cucumber is known for migrated into the center to create this scarlet nucleus. And so we were able to see how these tissues were changing and restructuring their internal tissues to better suit the life that they were currently living.

IRA FLATOW: Were they trying to become the whole animal again or not?

RACHEL SIPLER: It’s hard to tell from an early stage, but there’s no indication from what we can see that they were regenerating into a new sea cucumber, which is, I think, one of the more confounding or bizarre parts of this research, is that it’s not a form of cloning or fragmentation that we would see in other marine species. It’s actually these tissues just finding a way to best survive and best function in their current state as kind of a new biological unit.

IRA FLATOW: And Sara, this sounds like it was a surprising result. So what did it take to convince you that what you thought you saw happening was actually happening?

IRA FLATOW: Absolutely, I think we were all a little– we were just like, how can this be true? This is so bizarre. And it took a long time, I think, to convince ourselves that this is actually what we were seeing. And so we, as Rachel mentioned, started with just I mean, seeing how long these tissues will survive in natural seawater conditions. And then once they were surviving, we’re like, OK, well, there must be mechanisms supporting this. So is cellular proliferation happening? Is their immune system functional? How are they fueling theirselves? Where are they getting their nutrients from? And I think every new discovery just propelled us into a new question. And even though I think we’ve learned a lot, it really has just opened up, I would say, multiple careers worth of questions going forward.

IRA FLATOW: As a science reporter, we’re always taught back in science reporting school to ask this question. So I’m going to ask it because it seems relevant here. What practical value does this research give us?

RACHEL SIPLER: There’s a number of different areas of research that will benefit. I’m thinking of healing and regeneration for damaged tissues; tissue aging and longevity studies; tissue engineering to help keep these tissues alive, stable, and functional outside of the body; what we can learn for our own tissues or other tissues; providing this ethical and more accessible research model. Again, we think of HeLa cells and all of these different forms of mammalian cells that are harder for researchers to access. So this would give them a different model to use that without those biosecurity or access restrictions. Again, like Sara mentioned before, the study of immune systems– there’s just this huge wealth of opportunity for these organisms.

IRA FLATOW: I’m struck, Rachel, by, in the literature, calling it zombie sea cucumber parts. It’s, like, having fun with it. Does that help communicate what’s going on?

RACHEL SIPLER: I think it really does. And that we’ve been using that since the origin of this study. And it really brings life and a little bit of reality to what we’re looking at here. And with science, you need a little bit of connection. And this helps us connect to what these really are. It’s that dismembered part, the thing from The Addams Family, all of these different connections, this living tissue that is very on brand for a zombie discovery in 2026. Sara,

IRA FLATOW: Are you going to be known as the zombie researcher here? I mean, are you going to study this now?

SARA JOBSON: I’m hoping to be done grad school in the next month or so. And as in everything with academia, we’re going to pursue funding opportunities to keep working on this and just see where we can take it. I think for me, I would be really interested in looking at what the evolutionary purpose of this type of weird adaptation would be because, as I mentioned, they’re not reproducing entities. And so what types of environmental drivers are maintaining this regeneration?

IRA FLATOW: So is somebody going to be assigned to watching how long these organisms live? I mean, their not, what, three years or so.

SARA JOBSON: Yeah, I mean, we always have people in the lab keeping an eye on what’s going on, and we try and keep things going for as long as possible because, as Rachel had mentioned, without people that are making these observations and continuing to study them, we never really what’s going to come out of it.

IRA FLATOW: Well, I want to thank you both for taking time to be with us today. Rachel Sipler is senior research scientist at the Bigelow Laboratory, Sara Jobson, PhD student at the Memorial University of Newfoundland. Thank you both. Fascinating work. Good luck to you.

RACHEL SIPLER: Thanks.

SARA JOBSON: Thanks for having us.

IRA FLATOW: This episode was produced by Charles Bergquist. And if you have an unusual observation about the world, or maybe a question, we’d like to about it. Give us a call. The number is 877-4-SCIFRI. That’s 877- the number 4– SCIFRI. Thanks for listening. We’ll see you again. I’m Ira Flatow.

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