The Wonderous World Of Nudibranchs

This episode explores the fascinating world of nudibranchs, colorful sea slugs known for their unique biological adaptations.

1. Nudibranchs are highly diverse, with over 3000 species inhabiting marine environments globally.
2. They can absorb traits from their diet, including photosynthesis and venomous defenses.
3. Nudibranchs' ability to utilize stolen stinging cells for defense showcases an advanced survival strategy.
4. Their vibrant colors and patterns are not just for show but play roles in camouflage and mating.
5. The study of nudibranchs offers insights into evolutionary biology and ecological interactions.

1. Introduction to Nudibranchs

Maddie Sofia introduces nudibranchs, highlighting their diversity and appeal among marine biologists. Maddie Sofia: "Today we're focusing on nudibranchs, a particularly charismatic group of sea slugs."

2. Magical Traits of Nudibranchs

Discussion on how some nudibranchs utilize photosynthesis and others repurpose venom for defense. Ryan Hewlett: "They aren’t just beautiful; they are like superheroes of the sea."

3. The Science of Survival

Exploring the mechanisms nudibranchs use to incorporate and use foreign biological powers. Jessica Goodhart: "It's fascinating how they harness and repurpose the capabilities of their prey."

1. Explore Local Biodiversity: Take opportunities to learn about and observe local wildlife, which can be as fascinating as exotic creatures.
2. Support Marine Conservation: Engage with and support local marine conservation initiatives to protect diverse species like nudibranchs.
3. Educational Outreach: Share knowledge about unique organisms to inspire interest in biology and conservation among young learners.
4. Responsible Snorkeling: If observing marine life in their natural habitat, do so responsibly to avoid disturbing their environment.
5. Continuous Learning: Stay curious and keep learning about the natural world, as understanding complex ecosystems is key to their preservation.

Emily gets super nerdy with former host Maddie Sofia get as they dive into the incredible world of nudibranchs in this encore episode. Not only are these sea slugs eye-catching for their colors, some of them have evolved to "steal" abilities from other organisms — from the power of photosynthesis to the stinging cells of their venomous predators. These sea slugs are going to blow your mind!

People

Maddie Sofia, Ryan Hewlett, Jessica Goodhart

Content Warnings:

None

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Emily Kwong
You're listening to short wave from NPR.

Hey, everyone. Emily Kwong here with a favorite episode from our beloved founding host, Maddie Sofia.

Maddie Sofia
What's up, Duderino? Hey, today I've got a brand new d one for you. My last reported episode on some of the most magical invertebrates in the animal kingdom. Can you guess?

Emily Kwong
With you, it could be anything.

It just needs to be maximally slimy and gross. Am I close?

Maddie Sofia
Closer than I want you to be. Honestly, I don't like that. But, yes, we are talking about sea slugs, specifically, one big group of sea slugs called nudibranchs, or nudies, if you will. I didn't make it up. If you haven't seen one before, Emily, Google Nudibranch. These will actually blow your mind. Here's one of the scientists I talked to, Ryan Hewlett, straight up nerding out about them.

Ryan Hewlett
Like, when I think of these colorations and these patterns, like, you have polka dots, you have stripes, you have all shades of colors that I just don't see that often in other animals. Like, honestly, when I think of very beautiful animals, I think of nudibranchs.

Emily Kwong
Wow, what an endorsement. All right, I'm looking these up.

Maddie Sofia
Look them up.

Emily Kwong
Nudibranx.

Oh, wow.

Right? These are some gorgeous technicolor slugs. Is that what I'm looking at?

Maddie Sofia
Right. Yeah.

Emily Kwong
I mean, this purple one looks like it's going to a rave.

Maddie Sofia
They might be. They might be. And here's the thing. They aren't just out here looking pretty either.

Ryan Hewlett
I do think of them as having superpowers, and I think of some of the classical x Men characters who are able to steal other people's superpowers.

Maddie Sofia
So, Emily, some nudibranchs essentially have the ability to do that, eating up organisms from their environment and using their abilities for themselves.

Emily Kwong
You mean absorbing the power of your prey and using it for yourself? Yes. I am so here for this. Let's go.

Maddie Sofia
So today on the show, we dive into the incredible world of nudibranchs. Some that have evolved to harness the power of photosynthesis, others that can steal stinging cells from venomous predators and use them for their own defense. It's gonna be a solar powered sting. Stalin slug show.

Emily Kwong
This is classic Maddie Sofia reporting. You are listening to short Wave, the science podcast from NPR.

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Emily Kwong
Sofia, you're taking us on a sea slug odyssey today.

Where do we start?

Maddie Sofia
Okay, so like I said, today we're focusing on nudibranchs, a particularly charismatic group of sea slugs. They are remarkably diverse. They live in every ocean and most marine habitats. There are more than 3000 different species of them worldwide. And Emily, people are like really into them. Do you remember Ryan from earlier?

Emily Kwong
Yeah, he was pretty hyped on them.

Maddie Sofia
Yeah. So he's a PhD student at Harvard studying evolutionary biology. But before Harvard, he did his master's studying nudibranchs. And once you love nudibranchs, you don't just stop loving nudibranchs.

Ryan Hewlett
I live the passion every day, even though I've been working on other weird.

Maddie Sofia
Critters live in the passion, the nudibranch passion. He says that some scientists who study nudibranchs actually call themselves nerdebranks. And I love that when the fandom.

Emily Kwong
Has a name, you know, the passion is real.

Maddie Sofia
And I'll be honest, Emily, I was initially drawn to them because some of them are so cool looking. But for me, the amazing thing about nudibranchs is how they harness the powers of other organisms around them. And that's what I want to talk.

G
To you about today.

Emily Kwong
Yeah, this honestly fascinates me. Okay, so earlier you said some of these sea slugs have the ability to co opt photosynthesis, the process of using light to make food. I know that plants, algae and some bacteria do this, but, like, I've never heard of an animal doing that. How does that even work?

Maddie Sofia
Okay, so you're already on the right track. The key for nudibranchs is something you just mentioned, algae that use photosynthesis to make food, aka photosynthetic algae. Quite a few nudibranchs can do this, but let's walk through one particularly cool example. So there's a nudibranch called phyladesmium longicerum. These nudibranchs feed on corals, and hanging out inside those corals are photosynthetic algae.

Ryan Hewlett
Kind of this, like, mutualistic relationship where coral's giving them, like, a nice habitat to kind of hang out in, and the algae are providing them sort of with, like, nutrients and things like that.

Maddie Sofia
So when the nudibranchs eat up those corals, they end up eating that algae too. Now, instead of just, like, eating all the algae and excreting it, the nudibranch stores some of those algae in their digestive gland. And their digestive gland isn't, like, just in the belly of the slug, like our human intestines. They actually kind of extend up into these finger like projections called cerrata that grow and stretch out from the main body of the slug.

Ryan Hewlett
And what is interesting is that most of the time, this tissue, or this, like, projection is fairly transparent. And because of that transparency, like, light is able to enter and actually sort of, you know, hit those algal cells, and the algae are able to do what they do really well is to photosynthesize.

G
Whoa. Yeah.

Maddie Sofia
So the algae just kind of hang out inside the digestive gland of the nudibranch, making food, using light and producing nutrients the nudibranchs can use.

Emily Kwong
Let me get this right. Nudi eat the algae. Some of the algae survive and get stored inside the digestive gland.

G
Yeah.

Emily Kwong
And they just keep photosynthesizing.

G
Yeah.

Maddie Sofia
And in longisurum, the slug that we've been talking about, it is especially good at this. They've evolved these, like, really big paddle like cerrata, and so they can house these really well established, thriving communities of algae inside them. Hooking up these nudibranchs with nutrients.

Emily Kwong
They're essentially farming these algae inside of their bodies. That's incredible.

G
Yes.

Maddie Sofia
That is how scientists actually describe it. So they really rely on these algae. I mean, scientists have actually starved these nudibranchs for weeks or several months, and they can survive just on the nutrients from the algae. It's a beautiful piece of symbiosis, in my opinion.

Emily Kwong
It is beyond. I mean, could you imagine if we could do this? You know, like, you're running late, no time to eat. I'll just rely on my body's solar power.

Maddie Sofia
It's perfect.

Ryan Hewlett
It's perfect for us, you know, for the gal on the go. You really just like getting that, harnessing those algal powers.

Maddie Sofia
Just a solar powered gal on the go. Emily, I want this for the future.

Emily Kwong
Okay, so that's the solar powered nudibranchs.

G
Yes.

Emily Kwong
You've also mentioned that some nudibranchs can steal stinging cells from animals like jellyfish.

G
Yeah.

Maddie Sofia
So I talked to Jessica Goodhart about this. She's a postdoc at Scripps Institution of Oceanography at UC San Diego. And I think it's also fair to call her a nerdebranch.

Jessica Goodhart
It is the most exciting thing I could have imagined doing when I was an undergrad. I never even could have possibly imagined studying something like this. And they're just cool, ultimately.

Emily Kwong
What a nurtebrink.

G
Yeah.

Maddie Sofia
And Jessica's whole thing is studying how nudibranch steal parts of a venom filled stinging cell from other animals by eating them. And these nudibranchs eat some pretty gnarly animals.

Jessica Goodhart
So this includes things like jellyfish. It can also include things like portuguese man o war, which are a different kind of cnidarian. There's also anemones, things like hydroids, if you're familiar with those.

Maddie Sofia
They don't play. Right. And all of those animals have the capacity to fire these little harpoon like structures called nematocysts. And nematocysts are, scientifically speaking, pretty metal. Like, say you poke a little jellyfish, for example.

Jessica Goodhart
What happens is, if you touch the tentacles, these structures fire as if they are a harpoon into the tissues of the other organism.

What happens usually is that there's venom that's released, that's a mix of a variety of toxins and can cause really severe damage. This is what most people associate with jellyfish stings.

Maddie Sofia
These nematocysts are what the nudibranchs steal.

Emily Kwong
Oh, and you said they get them by eating the jellyfish or whatever, right?

Maddie Sofia
Right.

Emily Kwong
So how does the nudibranch not get stung to death as they try to eat them and, like, harvest their harpoons, right.

Maddie Sofia
So it seems like a few things are protecting the nudie throughout this process.

Jessica Goodhart
They use the mucus that they have or that they generate outside their bodies to basically prevent some of the medicis from firing.

Maddie Sofia
Now, I should say that some of those little stingy harpoons do fire, but the nudibranchs have this little cuticle in what is essentially their throat that protects them from those. And so essentially, they just poop out those little fire nematocysts.

Emily Kwong
Wow. A shield of mucus and a gut of steel. This is like real superhero behavior.

Maddie Sofia
I know it. I know it. So they poop out the ones that are fired, but there are some that don't fire either. Those prevented from firing, like we talked about?

G
Yeah.

Maddie Sofia
Hash mucus or potentially something even cooler. Jessica says it's possible that some nematocysts that make their way into the slug are kind of, like, underdeveloped. They're not, like, quite grown up harpoons yet.

Jessica Goodhart
And there is some evidence to suggest that what basically happens is that the nematocysts are maturing inside of the nudibranch. So the nudibranchs are able to create an environment that allow the nematocysts to essentially be prepared to fire. But we don't know for sure that that's 100% happening.

Emily Kwong
I can't with these creatures. Okay, so where do the slugs then put the little harpoons that they steal?

Maddie Sofia
Okay, remember the cerrata from the other nudibranchs we talked about?

Emily Kwong
Oh, yeah, those finger like projections that kind of come off the body of the slug.

G
Yeah.

Maddie Sofia
So these nudibranchs have cerata, too. And the unfired nematocysts make their way up there.

At the very tip of those appendages is something called the cnidosac.

Jessica Goodhart
And what essentially it is, is it's a sac. It's a muscular sac that has a bunch of cells that are the ones taking up the nematocyst.

Emily Kwong
Ah, okay, I get it.

Maddie Sofia
So let's say a little fishy comes along, maybe looking for a snack.

Jessica Goodhart
Basically, the cnidosecs squeeze their muscular structures so the muscles are squeezed and the nematocysts are released. And so the fish basically gets a mouthful of stinging, of stings. And, you know, if you were a fish, you might not be that excited about that.

Emily Kwong
Nudibranchs are incredible, maddy.

Maddie Sofia
I know. I think we should start saying dudibrank, you know, instead of duderinos.

G
Think about it.

Maddie Sofia
Think about it.

Emily Kwong
Okay, brilliant. Brilliant. Okay, if you could pick one of these superpowers, which would it be? The ability to harness photosynthesis from algae or the power of a jellyfish sting?

Jessica Goodhart
I mean, no.

Maddie Sofia
Like, not even a question. I would go the photosynthesis route. Like, I love a good symbiotic relationship. Kind of reminds me of us in a way, you know, of the whole shortwave team leaning on each other to make it through the tough stuff, protecting each other from the elements, providing each other food. When one of us forgot to eat, we've done that. You know that's real.

Emily Kwong
I will be your symbiotic slug algae any day. All right, dude Frank, that's the show for today.

This episode was produced by Brit Hansen, edited by Viet Le, and fact checked by Indycara. This is short Wave, the science Podcast from NPR.

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