Glowing Vomit, Cricket Serenades, and the Evolution of Animal Communication

Dr. Biology:

This is Ask-a-Biologist --- a program about the living world and I’m Dr. Biology. 

This episode is one in a series recorded at The Society of Integrative and Comparative Biology Conference – or SICB. I am going to add that the conference was held with great care and special protocols for COVID.

Ask A Biologist had the opportunity to setup a remote studio, close to the action and where we could catch up with several of the scientists at the conference. We also found out that some of the guests are making amazing robots. We even have plans to add instructions for building one of the robots to our companion website. So be on the lookout for that.

Right now, let’s head over to SICB and listen in.

[Background crowd noise.]

Dr. Biology:

Today we’re going to explore the communication methods of two very different animals. And I have to say they’re actually rather artistic in their own way.  One of the animals is a cricket that uses song to attract mates and the other – a tiny shrimp that’s using glowing signals to find their partner. Now the shrimp signals have been described as glowing vomit. Although after looking at some of the images taken of the signals, I’d say they’re some pretty artful vomit. These two animals are the study subjects of biologist and postdoctoral fellow, Niko Hensley. Let’s see if we can get the story behind these two animals and what lengths Niko has had to go in order to collect his data. I think you’ll see that being a biologist can have its perks and challenges. 

Welcome to Ask A Biologist, Niko. 

Niko:

Thank you for having me.

Dr. Biology:

What a perfect topic for a podcast. The evolution of communication. And well, this is one of those, I suppose, if you think about it. Podcasts have become incredibly popular these days, but we're not really talking about the same kind of communication in this case.

So, tell me a little bit more about how you're going about your study.

Niko:

That's a good question. I guess when I think about communication, I'm always trying to think about how two parties are trying to send information to each other, right? So right, like you said, that's definitely what we're trying to do in a podcast.

Niko:

But I'm more interested in how the natural world is really trying to achieve that same goal. We have lots of different organisms in the environment trying to send information to each other to try to accomplish certain goals, like finding a mate or finding food. And so organisms have evolved these complex systems in order to send that really important information to each other.

Dr. Biology:

So, you talk about organisms and we're animals, so we have a tendency to only think about animals. Do we also think about plants communicating?

Niko:

Yeah, I think one of my favorite examples is like fruit, right? We eat fruit all the time. How do we know if fruit is right for us to eat at that time? We look at its color, we look at its smell.

Niko:

But that's a communication signal that plants have evolved to tell other animals like bats or birds or rodents. I'm ready to eat. Please eat me. That way those animals can spread their seeds. So, like when an apple is red and ripe or when you smell that banana smell like those are signals that we pick up as animals, that the plants are sending to other animals in their natural world.

Dr. Biology:

Oh, OK. Do you work on plants?

Niko:

I don’t. That was just one of my favorite examples.

Dr. Biology:

So, what animal do you work on?

Niko:

Yeah. I work on it sounds a little cheesy, but I work on the bioluminescent mating signals of Caribbean shrimp, and I also work on the songs of Hawaiian crickets. So, they're very different animals, but they have very common goals.

Dr. Biology:

All right, let's start with first your bioluminescence. So, let's talk about that in particular. So, we are talking about animals that make a particular kind of chemical that allows them to glow.

Niko:

Right?

Dr. Biology:

Fireflies, right? Yeah. The most famous examples, right?

Dr. Biology:

Fireflies, right? And jellyfish.

Niko:

Yeah. Jellyfish. Some jellyfish.

Dr. Biology:

Okay. So, let's talk about your shrimp.

Niko:

OK, so we actually like to call them sea fireflies. They're not like fireflies that you find on land. They're not insects at all. They're shrimp. But we call them that because of how similar their bioluminescent signals are. So, in the Caribbean, the species only live in the Caribbean. They're about 100 of them. And at night on moonless nights, when the water is calm on coral reefs and seagrass beds, you'll have males swim up into the water and they'll start to actually vomit up little packets of glowing spit into different patterns.

And those patterns kind of look like you can think of it as like an airplane runway, all the lights that allow the plane to land so they vomit it up into these little different patterns. And then the females are swimming around in the water and actually following these trails of light in order to find the males and every species in the Caribbean, they have their own different pattern. And so, one of the big questions that we're trying to ask is why are these patterns so different across all these species? So, there's about 70 to 100 species. Most of them are very undescribed. They're not very well known because you have to go out at night, you have to go scuba diving at night with no lights and you have to catch them when the moon is really low. So, you're kind of like out in the dark, in the water alone. [laughs] And so in order to see this event and actually record these behaviors, you kind of have to like, get out there. And we're really interested in understanding why these species have all these different patterns that they produce.

Dr. Biology:

Wow. Out scuba diving at night in the dark.

Niko:

Yes.

Dr. Biology:

OK, I hear the little sound in the background, and I think of jaws, you know?

[Cello sound, two alternating beats of E and F]

Niko:

Yeah, exactly. So, we did for my Ph.D., which I just finished in 2020, that was maybe about five years’ worth of just like getting in the water and turning off all the lights and seeing what's in the ocean. 

[Faint sound of part of Jaws theme in background.] 

Dr. Biology:

Well, and you know, I'm teasing about sharks, and we actually just had a podcast with a really well-known shark expert, Jim Sulikowski. And one of the things we're talking about is sharks get a bad reputation. They're so important, and the likelihood of having a problem with a shark is far less than getting, as we know, struck by lightning.

Niko:

Yeah.

Dr. Biology:

All right. So, you are working on shrimp? They have bioluminescence, but it's, as you described it, vomit, bio... bioluminescence.

Niko:

Yeah.

Dr. Biology:

OK. And to make that even a little more unusual is we're talking about vomit in particular patterns.

Niko:

Yeah.

Dr. Biology:

How do they repeat that pattern? I mean, that's what gets me, I mean, not that I've had to vomit very often.

Niko:

Right?

Dr. Biology:

I don't think I've ever had the same pattern twice.

Niko:

Yeah, that's a really good question, actually, because these patterns that each species produces are really repeatable. We find that each species is like very tightly controlled on the pattern they make, and they don't overlap well with other species. So it's pretty specific for each one. And so, the control of that is really part of the question and the answer. I think right now this research is still very much in its infancy is we don't have an exact answer.

We don't really know, but it's definitely a current line of investigation. But I think one thing that might be helpful to understand is that when we say vomit these animals, they actually have a very special organ that controls how they produce and release this bioluminescence, right? We call it vomit just because it's like the most analogous thing that humans can think of. You might also think of it as like sneezing.

They have a big organ above their mouth, and it's in that organ that they store all these chemicals. So, they store this protein called luciferase. And then this really high reactive kind of vitamin called luciferin and they store it in these separate compartments. And so they have two compartments that keep those things separate. And then when they sneeze it out into the water, those two things mix. And when they mix, that's when the enzyme can degrade the vitamin and that will produce light. And so that's actually when you get this reaction to make all this like brilliant blue light in the water.

Dr. Biology:

So that's the triggering mechanism. Hmm.

Niko:

Yeah.

Dr. Biology:

And so, this is necessary for them to mate.

Niko:

Right. Well, so we don't know that it's necessarily per se for them to mate. We do know that the males use it to attract females. So, these animals let me give you a little more context on these animals themselves. These animals, unlike fireflies. Fireflies, they're not huge insects. But you know, they are a few inches long at the most. Our shrimp that we study they're about the size of a sesame seed. So, they're very, very, very small and they're really small animal living in a really big world because they're so small. They have really tiny eyes. And so, they have tiny eyes. That means they can't see very well, especially if you're trying to find a visual signal. So, it needs to be really bright and needs to be really obvious.

Niko:

So, these females are swimming around in the water, and these males produce this really, really bright light with these stereotyped patterns for the females to be able to, like, consistently follow. They also only do it at night when it's dark. So even if there's about a little over, I think about 5% of the available light in the environment. They won't make their signals at all. So, it really has to be quite dark. They're trying to maximize their ability to find a mate.

Dr. Biology:

Got it. Got it. So, you know, a full moon? No way.

Niko:

Right, exactly.

Dr. Biology:

Yeah. Got it. Hmm. Yeah. I just hadn't even thought about it. And then when we talk about communication again, we get really biased. We think about, you can talk, you can sing, you can write, you could draw, you could paint. You know, we think about those things, but we're not really thinking about bioluminescence. We're not really thinking about having to be really particular about when you do the communication. Hmm. OK. So that's one of the animals that you work on.

Dr. Biology:

You mentioned crickets.

Niko:

Yes.

Dr. Biology:

Hawaiian crickets.

Niko:

Yes.

Dr. Biology:

There's a biologist I had by the name of Marlene Zuk.

Niko:

OK.

Dr. Biology:

And there's an episode called Strange Cricket Silence.

Niko:

OK?

Dr. Biology:

And again, there it had to deal with parasites. And it's that kind of world there. You want to, you know, the idea of parasites and zombies and the other things that get us all interested in what is going on in the animal world. What's the story with your crickets?

Niko:

Yeah. So, I'm very well aware of the famous Hawaiian crickets that have lost their singing. I work on a completely different group of crickets. A lot of people think that all crickets are the same, but they're not. In fact, you know, crickets can be just as different as we are to like horses or something like that.

They can be very, very distantly related. And so, I work on these Hawaiian swordtail crickets, and these are small, flightless crickets. They're endemic to Hawaii. They don't live anywhere else in the world. And the really cool thing about these crickets is that they are the fastest radiation that is there many, many, many species in a very, very short amount of time for any invertebrate known in the world. So, they only live in the Hawaiian Islands. There are about 40 species, and all 40 of those species have evolved on those islands since the islands came into being, which is just a few million years.

And so, it's a little hard for people outside of biology to imagine. But usually, we think of species as kind of like accruing slowly over time and in these Hawaiian Islands with these crickets, there's many of them very, very quickly that have happened.

And we think that's primarily because of how they can talk to each other. And so, the females are listening for the males to sing. We all know crickets sing these lovely little songs and our crickets in Hawaii, they sing a very, very simple song. And the only difference between the species is that they sing their songs at different rates. 

[Cricket sound/song in background] 

So, some sing fast and some sing slow. But we think that the females are choosing different songs based on how fast they sing them. And that's really what's caused this different species to branch out.

Dr. Biology:

So, you talk about rapid change in evolution.

Niko:

Mm-Hmm.

Dr. Biology:

And that's true. We often think of evolution taking a really, really long time. But that's not always the case. And so, this is one of the things you're talking about. 

Dr. Biology:

And did you say 40? Was that the right number 40 species?

Niko:

Yeah, 40 species.

Dr. Biology:

All right. So now we've got two kinds of communication are going on here. One is with your shrimp, and I love the fact that they're the size of a sesame seed.

Niko:

Mm hmm.

Dr. Biology:

So, when you're out at night, does it ever look like starry night or something in the ocean?

Niko:

Yeah. What we usually say is that looks kind of like a fourth of July fireworks show. But Starry Night is equally equivalent. It's lots of little pinpoints of blue light that kind of crescendo as the night goes on, you have these waves of different signals kind of come on and you have many species going in one place. You can have up to ten different species. So, you have ten different patterns going in the water and you have hundreds and hundreds of males going at the same time. So, it's just like different kinds of fireworks or fireworks show.

As you know, you go out and sit out the fourth of July, you see the different patterns. And you know, there's always like a big finale, the end of a fireworks show, you know, that'll be one species or another, depending on where you are in the Caribbean. These only occur in the Caribbean Ocean.

Dr. Biology:

So, for those listeners that have a podcast application that allows you to see the artwork, we are adding artwork now to the show, so we'll make sure that we put in some images.

Niko:

Yeah.

Dr. Biology:

That you can look at to see what these look like, because it sounds just amazing.

Niko:

Yeah.

Dr. Biology:

And so, it gets me into this realm of the world of biology and science.

Niko:

Mm-Hmm. 

Dr. Biology:

So, if you ask someone. Typically. Someone that does the stereotypical scientist, they're going to be a person in a white lab coat at a bench with beakers.

Niko:

Mm-Hmm.

Dr. Biology:

But they don't understand, is that being a biologist one of the perks is travel. And travel, not just to normal places, to exotic places and doing things that aren't the norm. So. You're able to do some things that I would say are not the stereotypical biologist or scientist. Is that what you thought you were going to be doing? 

Niko:

Yeah. I think one of the reasons I got into this kind of biology, evolutionary biology specifically, is because I was able to do things outside the norm. I loved being able to go into the natural world and see organisms existing in the place where they're supposed to be.

Niko:

I mean, I grew up going to zoos as a child, and I loved seeing the animals there. But being able to go into the world where they live and kind of experiencing their own habitat, their own realm and trying to get your brain and your mind in their position to ask questions about like, well, how do they see their world? And how are they solving the challenges that we think about as challenging for us all the time, like in communication? And really trying to figure out those questions. You have to go there. You have to understand really deeply their natural history, and this kind of job really gets you to be able to do that. I found that so intoxicating. 

So, yeah, when we go to the Caribbean, we get to go and stay at these marine stations, and you go out on the boat every night to collect these animals over two weeks and you have to time it right with the full moon so that you know you're going out not at 3:00 a.m. but at 8:00 p.m. And you're missing the moon and you have to make sure you're catching it within the windows that the animals are there. So, it's very challenging in that regard logistically, but also like intellectually challenging. And I find that really, I don't know. It's just it drives you to do it all of the time. It's so motivating.

I think one of my favorite things or my favorite anecdotes of doing this kind of work is I had to do fieldwork in Belize for a month and I was staying with a collaborator who was on sabbatical there, and we decided that it was just more economic if we stayed on a small island. But this island had no infrastructure and I actually mean no infrastructure. There are no buildings on the island.

Dr. Biology:

No, no power.

Niko:

No, certainly no power. But like there was one wooden house. And so, when I arrived on the island, I didn't actually have a place to sleep and we had to build the structure that I was going to sleep in and perform all my work in while I was there before I could start anything like we had to import the materials, we had to nail it together with corrugated roof. Our lab space ended up being like four posts, a piece of metal, and a bunch of black tarps. And that was where I did all my experiments for that month, you know, and I had to bring in camera equipment and build tanks to capture my animals in. And it's kind of like the woodsmen version of doing science compared to like a very sterile, clean lab environment. But it presents its own challenges. And of course, being there, you got to see the animals in their habitat and like, you're able to refine the questions you're asking because you're trying to understand where they are and what they're doing when they're there.

Dr. Biology:

Wow. So, did you have carpenter skills?

Niko:

Oh, no, and I certainly don't now. I mean, it wasn't. It was not like, well, put together, but it sufficed, right? And just like in evolution like it doesn't need to be perfect. It just needs to get the job done. [laughter]

Dr. Biology:

Right. And you can refine it later if you need.

Niko:

Exactly. And of course, we had carpenters, assistants and I was not doing this alone. I certainly couldn't. But it's so amazing being a biologist, all the skills that you have to pick up on that you don't think are associated with science, you know, like carpentry or video editing or all these things that you never knew you needed to know in order to get your science done. There's a wealth of skills, just a lot of hats to wear.

Dr. Biology:

Absolutely. So between your two animals, between your shrimp and your crickets, do you have a favorite?

Niko:

I love them both equally, especially if this is going to be for a public audience. I definitely can't say that I have a favorite.

Dr. Biology:

Well, you think it's going to get back to them and they're going to ... [laughter]

Niko:

[laughter] I don't want to. I don't want to make any enemies. I'm still a trainee. I love my shrimp. I miss the water a lot. I love diving. And the marine environment is so different from what we experience on the day to day. It really gets you out of your zone. And so just being able to get in the water and kind of like that weightlessness and seeing an alien world, even though it's not alien at all, it's 70% of the planet. That is really amazing. But my crickets are wonderful because their songs are beautiful. And also, you get to work in the middle of the day, which is very novel. Most of my Ph.D., I had to be very nocturnal. My animals are nocturnal, so it's nice to be able to go to bed when the sun is down, and not have, like, a completely reversed schedule.

Dr. Biology:

Yeah, no, I can imagine. So, Nico, did you learn to scuba dive before you became a biologist or was it for it?

Niko:

Yeah, it was part of the skills I had to pick up as a biologist. Actually, I joined a lab, and I didn't know what organism I would be working on and my Ph.D. advisor said. You know, we're starting this project on these sea fireflies. They're in the ocean, they're in the Caribbean. Do you want to work on this? And I took the opportunity in order to really sink into that research, I had to learn to scuba dive and get scientific certified, which is another certification above your normal certification. Safety diving, which is another certification above that.

So, there are lots of layers of training that had to go in just to be able to accomplish the work. And I was really fortunate to be at a place where that was easy because scuba diving isn't necessarily the most affordable or amenable kind of skill that you have to pick up. And I was in California on the coast, so we're at a school that was well equipped to be able to do that. The work would have been much more challenging to accomplish otherwise. But yeah, I had to. I had to learn to scuba dive. I had to learn how to build nets and catch these shrimp. I had to learn how to do so many things that I can't even list them all right now. But I'm sure any scientist, especially a field scientist, could say the same.

Dr. Biology:

Nico, you used the word "we" a lot and quite frankly, I do the same thing, but maybe not for the same reason. So, what's the "we" for you?

Niko:

The “we” for me is that I feel like all my efforts as a scientist are really in a collaboration with others. I think it takes a lot of people to make a little bit of knowledge to really understand the truth in the world, and no person does it alone. And so, I really like to give credit attribution where it's due, and I have so many people to thank. So, I use we as an honorific to really understand that it's a process that we are embarking on collectively.

Dr. Biology:

Right? And it's no longer the lone scientist in the lab.

Niko:

Right.

Dr. Biology:

It is highly collaborative and mainly because the problems we're facing these days are very complex and growing even more complex each day.

Niko:

Right.

Dr. Biology:

And it takes more scientists more minds thinking about it to find out what there is that we have not yet discovered.

Niko:

Right. And I think one of the really important parts about that collective effort is that like, you get really diverse opinions, right? Not everyone thinks the same way. And so you can get really different perspectives on the same problem and you never know when that's going to provide a really transformative solution.

And so having a collective knowledge in a group and really trying to gather information from different, diverse perspectives is really important in order to problem solve. We can see that it helps problem solve and troubleshoot much faster and much more creatively. And so, yeah, I say we because I'm really interested in making sure we have those diverse perspectives.

Dr. Biology:

Well, this is leading me into. There are three questions I always ask my scientists.

Niko:

Ok.

Dr. Biology:

So, this is a perfect time to ask them. Was there a point in your life? Or I often say an aha moment when you said, I want to be a biologist, or I want to be a scientist?

Niko:

Um, I knew I wanted to be a scientist when I was about five or six, and that has always been the goal. I think that was largely inspired by the Magic School Bus and Bill Nye being on TV all the time. I mean, it made science seem very fantastical, which it is. It's just not exactly in that shape, And I played a lot of Pokémon as well as a younger child. And I think collecting animals was very inspiring. So, I think those things melded in my brain to make me want to go out and study animals.

Niko:

So, I knew maybe at five or six that, yeah, I want to be a scientist. I just didn't know how to be a scientist. And so that was more the process was to discover how to get into science. But it's always been there, that intrinsic love of the natural world, I think.

Dr. Biology:

The next question is where I get to be a bit on the well, sometimes I say it's mean and sometimes I say I'm just being mischievous.

Niko:

OK.

 Dr. Biology:

Because I'm going to take it all away from you. 

Niko:

OK. 

Dr. Biology:

You can't be a biologist. Scientists, I'm taking away your science. A lot of times my scientists have gotten hooked on teaching. A lot of us love teaching.

Niko:

Yeah.

Dr. Biology:

So, I'm going to take that away because I know that's sometimes where my scientists will go. Here you get to have a magical power to be anything or anyone or do anything. What would that be if you're not doing your science?

Niko:

A magical power to do or be.

Dr. Biology:

I mean, I'm giving you the power. You're not going to have a magical power.

Niko:

Oh, OK.

Niko:

So, to be clear, I was like, Do I have to come up with an ability?

Dr. Biology:

No, no.

Niko:

Just like rewrite history, but ...

Dr. Biology:

Iv'e taken away the thing that you love and I'm going to make you go for that second love.

Niko:

OK. Yeah, great question. I think I would want to be a fiction writer. I loved reading as a child. I still love reading now. And I consumed a lot of fiction as a child, and I think the power to bring stories to people also part and parcel to scientific career. But being able to do that with your imagination is a wonderful gift to give to others, and it's also a type of communication in many ways. So, I think being a fiction writer would be probably high on the list.

Dr. Biology:

You read my mind. I was going to say, Let's talk about communication. Absolutely. Is there a particular writer you like?

Niko:

Mm hmm. You know, I have a lot of fondness for stories from like fiction from the Eighties. I was really fond of a book series by David and Leigh Eddings from the eighties. It was a guy finds out that he has magical powers, and he has to save the world kind of story. And that was really popular, and I also love Dune. Dune was one of my favorites as a kid. Yeah. And then, of course, the classics like Harry Potter. I guess that's more my generation. But yeah, I'd say those are the big ones off the top of my head.

Dr. Biology:

Well, the last question I have is what advice would you have for the next generation of scientists that are coming up? What advice would you give them?

Niko:

Yeah, this one is one I like to think about a lot because as you said, teaching kind of becomes a large part of our experience as scientists. And I think one of our primary goals isn't just the development of knowledge, but it's development of the next generation of people who seek knowledge, right? Like the endeavor is, they'll always be able to produce knowledge, but that's not a one-person goal. So, I think it's really important that we think about how to foster the next generation of scientists.

And I think something that has become very important to me, but also something I see in students that I've taught is to not be afraid to make mistakes. I grew up as a child, but also in science. I was really afraid of doing the wrong thing all the time, making mistakes, you know, kind of getting the disapproval of my mentors or superiors or making the wrong choice that would lead you down the wrong path. And I think in science, it's really important to make mistakes because that's how you figure out what does and doesn't work, whether that's on a personal level or professional level, you have to be able to explore all the options.

And in science, you know, we don't want to just support the one theory we have. We want to make sure that our theory is right. And so, in order to do that, you have to develop many ideas and check out the ones that are wrong to know they're wrong and then find support for the ones that are right. So that kind of fearlessness and discovery and exploration is super, super important. And I tell my students like, don't be afraid of making a mistake, like, never be afraid of asking a question that has an answer or that's wrong or that you think is wrong. Always ask the question, always make that mistake, because that's where you learn. Science is about learning and making knowledge, and so be fearless.

And sometimes that's just that like communicating and reaching out to other scientists, right? Send that email. Call that professor or something like talk to those people. Make those connections. Even if that seems scary, the worst they can say is is no, and you'll be right back where you started. And so, the best that they could say is yes, and then you've developed a whole new connection. So don't be afraid to talk to those people. Reach out and seek new knowledge. I think that's that's the one thing that I found. It's really important for students.

Dr. Biology:

I love it. The idea that we're going to always get it right the first time. That's wrong.

Niko:

It's wrong. [laughter]

Dr. Biology:

So, the idea here is if you never want to make a mistake, you'll never do anything.

Niko:

Yes.

Dr. Biology:

I love that advice. Now, Nico, I want to thank you for being on ask a biologist.

Niko:

Thank you very much for having me.

Dr. Biology:

You have been listening to Ask a Biologist and my guest has been biologist and NSF postdoctoral fellow Niko Hensley. 

As a reminder we’ve started adding images to our chapter sections on our podcasts. If you have a player that supports chapters and pictures, we have added some images that we talked about in this show. So, check them out.

The Ask A Biologist podcast is usually produced on the campus of Arizona State University and is recorded in the Grass Roots Studio, housed in the School of Life Sciences, which is an academic unit of The College of Liberal Arts and Sciences. But for this show we are at the annual research conference for The Society of Integrative and Comparative Biology – also called SICB.

And remember even though our program is not broadcast live, you can still send us your questions about biology using our companion website. The address is askabiolgist.asu.edu. or you can just Google the words Ask a Biologist. 

As always - I’m Dr. Biology – and I hope you are all staying safe and healthy.