Short Wave - Life After Whale Death

Episode Date: November 7, 2019

What happens after a whale dies? Their carcasses, known as "whale falls," provide a sudden, concentrated food source for organisms in the deep sea. Biologist Diva Amon is our guide through whale-fall ecosystems and the unique species that exist on these fallen whales.See 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

You're listening to Shortwave from NPR. Maddie Safaya here with shortwave reporter Emily Kwong. Hi there. What kind of science gems have you unearthed for us today, Kwong? Have you ever wondered what happens after a whale dies? Yeah, of course. I wonder it all the time. And the internet tells me that they wash up on the shore. Some do.

Okay. But most actually fall. Sometimes all the way to the bottom of the ocean floor. whale falls, as they're called, are entire ecosystems onto themselves. Cool. Right? Scientists often stumble across them while exploring the deep sea, sometimes with a submersible, other times with a remotely operated vehicle they control from the surface. Yeah, and a few weeks ago, the EV Nautilus, a research vessel under the direction of Robert Ballard,

the guy that discovered the Titanic? That's the one. Using one of these remotely operated vehicles discovered a whale fall. believed to be some kind of baleen whale off the coast of California and live streamed what they saw. You're hearing the collective awe of everyone on the nautilus. I'm hearing a bunch of nerds is what I'm hearing, which I like. Honestly, these scientists can barely contain their whale puns. We did not find this whale fall on porpoise.

Okay. Honestly, in my experience, scientists aren't trying to contain their puns that hard. Nor their wonder, apparently, at all the creatures scavenging this whale. carcass, they're panning the camera up close and looking at everything that's covering the bones like a squirmy, shaggy carpet. Wow. Wow. The dinner bell ringing, right?

We are so excited up here to say. Today on the show, what happens after a whale dies and how biodiversity finds a way at the bottom of the sea? Okay, so whale falls. What are they exactly? Well, to find out, I talked to a deep sea biologist. So my name is Diva Amon, and I'm originally from Trinand, Tobago, but I'm currently based at the Natural History Museum in London. Diva grew up swimming and sailing and snorkeling in those waters of the Caribbean.

She studies the deep sea, human impacts too. And every so often, researchers like her will come across these whale falls, carcasses that have floated down to the bottom. Diva likens them to food packages from the sky. Yeah, for the creatures down below to consume. Okay, and what is it like down there? Like in the deep sea? Cold, dark, very, very dark. High pressure, all the water pushing down.

And it's also full of these very interesting organisms that you can see when they turn those lights on in the submersibles. And they will, some of them will feed on little bits of matter that are falling from the surface almost. like snow. So it's mostly dead plankton, dead shells of animals, their poop. That forms marine snow. But occasionally, you tend to get larger packages of food. So things like dead whales or trees or mantarays or turtles. When they die, they often drift down into the deep sea. And when they hit that deep sea floor, it's like Thanksgiving or Christmas. And like your family. And like your family come from all over the country for these events. You know, different species come from all over the deep sea.

So, like, they don't want to be there, but there's so much food that they have to. You know what I mean? You can't pass it up. I mean, this is like a Christmas miracle. It can nurture that part of the deep sea floor for centuries. The whale, average whale carcass, has two tons of carbon in it. Holy crap. Diva said that's the equivalent of 2,000 years' worth of the marine snow we were talking about earlier.

That just normally falls down. That normally falls down from the surface, exactly. Wow. Okay. And so what kind of creatures enjoy freshly fallen whale? This is the coolest part to me. Well, there are different stages to a whale fall. And each step brings different organisms to the table.

Putting the tablecloth out there, a whale has freshly fallen. First is the mobile scavenger stage. Big fish like sharks and rat tails and hagfish and big crustaceans like isopods, which are kind of like roly polis and amphibods and lobsters. They come from far and wide to feed on the flesh of the whale. Okay, they're first to the buffet. Exactly. They're those relatives who can't help themselves.

Exactly. And they just clean it up, clean it up, clean up, clean up that carcass. And they clean the carcass to the bones, creating this nutrient. rich area in the surrounding sediment that sets the table for stage two, the enrichment opportunist stage. Yeah, and a completely different group of animals pull up a chair to eat. So you'll get things that are much smaller in size. So little crustaceans or little worms, a lot of things that live in the sediment and sort of eat up all those little crumbs that have been left, essentially, from the feeding activity before. giving way to stage three, the self-fulfilling stage, when just the bones are left and bacteria break down fat trapped inside those bones.

And while they do that, they produce hydrogen sulfide as a byproduct of that reaction. Like the gas found in drilling for like oil. Yeah, it smells like rotten eggs to us. But that hydrogen sulfide is used by different bacteria and other microbes to power their life. It's a process called chemosynthesis. It's where chemical energy is used to. make food. And so again, you get a completely different set of animals. A lot of bacteria, these thick bacterial mats that grow all over the bones and a white and yellow and orange and

a sort of can glow. And scientists now suspect there's a fourth stage called the reef stage. Keeps getting better. Right? Where the whale bones have been picked so thoroughly apart. They create a structure somewhat like a coral reef. Huh. Yeah, it's this whole ecosystem on the deep sea. So cool. And there's entire species that were first discovered on whale bones. You know what, Kwong, evolution's the best. Yeah, the biodiversity there, especially in stage three, I got to say, is unlike any other community on the deep sea floor that you'll find. I'm talking chemosynthetic clams. Yes. Muscles. All right. Snails. And what Deva calls the most charismatic bone-eating worms. Yes. They eat the whale bones called oscidacs. And up close,

they look like bright red trees or pink trees with little roots. And they use that root structure to burrow down into the bones of that whale and suck out the nutrients, basically. And so they live only on the bones of dead animals. And so, I mean, what a crazy way of life, right? Like life in the deep sea finds a way no matter where it is and what it is, it will find a way. It always does. All this evolutionary novelty is housed in the ecosystem of a whale fall. And that is why Diva says it's worth studying and protecting.

While we know more than we ever have, we still have so many questions. And understanding the importance of many of these habitats in the deep sea, such as whale falls, is still new and emerging. And so there could be reasons that we need them around that we don't yet know. According to Noah, less than 10% of the ocean has been mapped by sonar. Wow. Less than 10%. And even in those mapped areas, we don't necessarily have a great idea what's happening on the seafloor. That's wild.

This is amazing. This is an amazing episode. It's got evolution. It's got microbes. It's got Christmas. I made it for you. All right. Emily Kwong, thank you so much.

Thank you, Maddie. We'd also like to take a moment to acknowledge the recent passing of Alaskan scientist artist, artist, and radio host, Richard Nelson, who we featured on our episode about the Tongass National Forest. Hi, I'm Richard Nelson for Encounters, a program of observations, experiences, and reflections on the world around us. So, to close out this program about whales, here are some humpbacks Richard Nelson recorded from his program encounters. while paddling in a little orange kayak, microphone pointing towards the ocean, listening as he always was to the natural world.

Do you hear that kind of siren sound in the background? Faintly audible. Oh, we heard the feeding call of the humpback whales and then the sound of this congregation of whales erupting through the surface of the water. Today's episode was produced by Britt Hansen and edited by Viet Le. This has been NPR's short. wave. We'll see you tomorrow.