Webinar: Living and Fossil Sea Urchins
Aired May 15, 2020
Maggy Benson:
Hey everybody, welcome to Fossil Friday. Hey everybody, happy Friday. My name is Maggy Benson and I'm a museum educator at the Smithsonian's National Museum of Natural History and I'm here today connecting youth to some of our amazing paleontologists from the Smithsonian's National Museum of Natural History. We have a really fun day planned for you. Now, while everybody is joining me we want to give everybody a moment. So take a moment to look at the bottom or the top of your screen to find our chat button, find our chat and tell us where you're tuning in from and we'll be able to read some of those locations in a moment here. I'm going to go over a couple logistics for how to participate in today's program while you're telling us. So today's program, our Fossil Friday event we are going to be meeting paleontologist Dr. Camilla Souto and we're going to learn about Camilla's career at the Smithsonian and we're going to be asking you a lot of questions during our program, and we're also going to be taking your questions.
So we want to invite you first to find that chat, because that chat is where you are going to respond to the questions that we ask you. So where are you from? You're all responding really quickly, and I'm going to read some of those right now. All right. We have New York, Los Angeles, Boston, Maryland, Massachusetts, India, Delaware, Virginia, more Maryland, New Jersey, Tennessee. All right. Louisiana, Scarsdale New York, California, Utah, Brazil, New Jersey. All right, lots of Maryland and Virginia so happy to have you. Hendrix, Utah, Colorado, West Virginia. All right, Canada, more Utah, Pittsburgh, Pennsylvania, Essex Falls. All right, we're so happy to have so many people from around the world. Australia, Washington, Los Angeles, Derby England, welcome everyone. We are so happy to have you here with us today to learn about paleontology in our ongoing series of Fossil Friday. So you can continue telling us where you're from in the chat, and we'll try to shout out a couple more of those.
But I'm going to go over a couple more logistics before we meet our special guests. So the chat again is where you're going to respond to the questions that we ask you during today's program. Now take another minute and look around your screen and find the Q and A. This is where you're going to post questions that you want our scientists to answer during the live program. Now we'll be taking some of them for our special guest Dr. Camilla Souto to answer live. But we also have a couple other paleontologists who are going to be responding directly to your questions in the chat. So I'm going to let them introduce themselves now. Hey, Rich. Hey, Scott.
Scott Evans:
Hey, Maggy.
Maggy Benson:
Hey, can you guys tell us a little bit about what you do?
Scott Evans:
Yeah. So I'm Scott and I'm a paleontologist at the Museum of Natural History and I study things that are a little bit older and a lot squishier than what Camilla is going to talk to you about today.
Rich Barclay:
I'm Rich Barclay, I'm also a paleontologist. I study fossil plants, so yes there are fossil plants. Plants preserve quite well and we use them to study paleoclimate because they adjust rapidly to their conditions around. So looking forward to your questions.
Maggy Benson:
Thank you guys so much for joining us. So Scott and Rich are going to be in that Q and A responding to some of the questions that we don't take during our live program. So when you submit questions to the Q and A, and the chat please know that we are receiving them but you won't see your other friend's comments or questions there. You'll only see the questions that Rich and Scott directly respond to and we'll be reading a lot of the questions during the program for Camilla. All right, now we also have paleontologist, Dr. Laura Soul here today with us and she's going to be facilitating our conversation with our featured marine paleontologist Camilla Souto. So welcome Laura, welcome Camilla. We have an audience today from around the world, across the United States. We have England, we have Australia, Canada. So why don't you take it away Laura.
Laura Soul:
Thanks Maggy. Yeah. So my name's Laura Soul, so I'm a paleontologist at the Smithsonian and I also work with Maggy in our education department. I'm going to be chatting with Camilla Souto today who is also a paleontologist at the Smithsonian and she studies marine invertebrates. So that's animals that don't have spine, they don't have bones and they live in the ocean. So marine animals that live in the ocean and she's especially interested in using different species of fossil and living echinoderms. So that's things like sea cucumbers and sea urchins. So hi Camilla, do you want to introduce yourself?
Camilla Souto:
Hi Laura, hi everybody, I'm very excited to be here. So as Laura and Maggy mentioned before, I'm a marine paleobiologist. Which means that I study marine animals, that are both fossil and also living and I use the fossils to understand the living and I use the living to understand the fossils and it's very exciting.
Laura Soul:
So I remember you telling me that you've always been really interested in the ocean, even from when you were a child and you had some pictures that you wanted to share with us?
Camilla Souto:
I do. In the picture that ... Oops, let me find it here. My mom just sent me on Mother's Day. So here I got a picture of me and my cousins here on the left, I was about four to five years old. I'm from Brazil and I did not grow up close to the ocean, but every summer my parents would take me there to this place and I would spend all the time in the water and looking for marine organisms, and then I grew up and I decided to be a marine paleobiologist. So part of my work happens in the oceans like looking for marine organisms, like here I am looking for a sea star. But most of my research happens at the museum collections, so here I am in a small section of the collections at the Smithsonian. As Laura mentioned before, I study echinoderms and many people ask me if I've discovered a new species. So here are some species that I've discovered. So they're all living and most of them are sea cucumbers.
They look like worms, but they are echinoderms and one sea urchin and I'd just like to highlight that these species here in the middle is a brand new species that just been described and you're all the first ones to see it.
Laura Soul:
Cool. Nice, I like that. Okay. So these are all different types of echinoderms and so sea stars are echinoderms as well, right?
Camilla Souto:
Sea stars, sea cucumbers, which are these squishy echinoderms. Sea urchins, there's a type of sea urchin that I'm going to talk more about later. There are also brittle stars that look like sea stars and there are feather stars.
Laura Soul:
Okay, great thanks. All right, so we have had a few questions come in from people who are watching.
Camilla Souto:
All right.
Laura Soul:
The first one that we've got, people would like to know what do you like about your job?
Camilla Souto:
What do I like about it? So I really love the discovery aspect of being a scientist. But something that I really like is the versatility of being a marine paleobiologist. So sometimes I am in the museum collections examining specimens, sometimes I am in the field looking for animals. Sometimes I'm by the computer writing scientific articles or preparing lectures. Sometimes I am in the classrooms teaching for my students, sometimes I'm in the museum exhibits talking to all of you. So I really like this versatility that we have.
Laura Soul:
Great, and then somebody has a follow up question about those new species that you showed us. Do you get to name those species when you find them?
Camilla Souto:
I do get to name them and it's the most fun part of all of it because you can be creative and come up with different names. So sometimes we honor other scientists, so one of the species I described I named for a tribe of native Brazilians from the Amazon that were extinct. So the [inaudible 00:09:23] so I named this species for them. So it's really cool.
Laura Soul:
That's cool. So you also study fossils as well, right? So do you both find fossils too?
Camilla Souto:
I do study fossils. I haven't done much field work looking for fossils because most of my fossils they're spread all over the world. So it'd be very expensive to go to all of the sites, so instead I go to museum collections and I look for them.
Laura Soul:
Okay, great. All right. So we found out a bit about you and I think you are going to talk to us a bit more about sea urchins and how you study them, if you want to start your slideshow again.
Camilla Souto:
Yeah. Before that though, I have a question for everybody. So what animals have you found at the beach?
Laura Soul:
Good question. All right, everyone tell us in the chat. When you go down to the beach, you go to the ocean, what animals do you find there? Okay, we're getting lots of good answers coming in. Lots of shells, crabs, starfish, jellyfish, dead sea urchins. That's definitely true. Someone said dolphins, seagulls, shells, lots of people saying shells. Okay, turtles, fish for sure. Great. So there's general consensus. We find lots of shells and crabs and fish and things like that. Was that the answer that you were looking for?
Camilla Souto:
Yeah, those are great answers. We find all of that and you find even more organisms in the ocean. So all of these here, and I'm very surprised that many of you mentioned many invertebrates which are the animals without backbone. So all of these here are marine invertebrates and the one that I'm going to talk to you about are the sea urchins. So when you think of a sea urchin, I'm sure you think of spines right? So the sea urchin have lots of spines that can hurt us sometimes, but they use those mainly to protect against predation. So here I have a video of a purple sea urchin here in the bottom and there is a crab on top and if Maggy can show that video for me. You're going to see that the crabs going to use the claws to break the sea urchin spines. So even though the sea urchins are using those spines to protect their bodies their predators, they're able to go through that cover of spines and break them off to be able to eat the sea urchin.
So this is a video I made in my aquarium last year, I thought it was really cool to show. You can see even there are some spines here, they're already broken.
Laura Soul:
So the sea urchin has spines to defend itself, but the crab is really good at overcoming that to still eat it.
Camilla Souto:
Very good. Crabs, some fishes are good too, yeah. Then after you go through that cover of spines, what make up the body of the sea urchin? So here is a sea urchin free of spines. So all of the spines have been removed and this is a three dimensional image that I made and there's another video that I'm going to ask Maggy to show you again and you're going to do a cross section of the skeleton. So this is the sea urchin skeleton that you're going to cut. So these are small plates, they're bound together by soft tissue which is made by a protein called collagen, mostly in other components. Collagen is very common in our skin, in our muscles and also in the body of the sea. So instead of a solid body that people think the sea urchins have, they actually have many plates bound together by the soft tissue and the soft tissue allows the sea urchin to expand and contract. So you're looking here at the mouth of the sea urchin from the inside. Thank you Maggy.
The sea urchins that I study are of these kind here and you can notice very quickly that this sea urchin does not have the big spines that you usually look for in a sea urchin. So how do you think the sea urchins avoid to get eaten if they don't have the big spines?
Laura Soul:
All right, what do you think everybody? Tell us in the chat. What's another way that you could avoid being eaten if you were a sea urchin and you don't have big spines? So we've got camouflage, be poisonous, runaway, hide, we've got hide. They might have poison, blend in, venom, someone said bury themselves. What else? Have smaller sharp spines, be yucky tasting, that seems like a good strategy to be disgusting. Okay, so we've got a lot of people saying camouflage or blend in or have tiny spines. What's the answer, Camilla?
Camilla Souto:
They actually blend in because usually these urchins are not very colorful, so I would take that answer as well. But something these urchins also do is that they live buried in the sediment. So if you want to look for the sea urchins, you have to go down to the bottom of the seafloor and sift through the sediment to find the sea urchins. Like the scuba diver is doing here in the picture on the left and on the right you can see a sea urchin that is burying in the sediment. So usually they're very hard to find. So that's why I usually see the sea urchins that have big spines instead of the sea urchins with the small spines. So I'm going to talk a little bit about how this group of burrowing sea urchins evolved and this happened right after a really big mass extinction. So you're all acquainted with the Cretaceous mass extinction, which is the extinction that wiped out many dinosaurs, if you consider the birds are dinosaurs.
But the extinction that led to the evolution of these sea urchins happened way before that about 250 million years ago, which we call the Permian mass extinction. That was the greatest extinction of all because it killed about 95 percent of all marine animals, which is a great percentage. We understand that intense volcanism at that time led to the change in composition of the atmosphere and of the oceans, which became toxic to the sea urchins and other marine organisms as well.
Laura Soul:
Now was this like volcanoes all over the planet?
Camilla Souto:
There was massive volcanoes, yeah pumping lots and lots of gases in the atmosphere and that led to ocean acidification, that led to depleted oxygen levels in the atmosphere. So that was really bad for the organisms and many of them were completely wiped out. The sea urchins that lived before that extinction, they all had these long spines that we usually see when you find sea urchins and then when you wipe out most of the organisms like it happened in this extinction. After the extinction, the survivors they actually diversify a lot because they have all the resources for themselves. So this period right after the extinction we called the Mesozoic marine revolution. Which was a time where many of the predators evolved great ways of predating on their prey and the prey evolved many interesting ways to defending themselves from the predators. So you can see here crabs and marine snails and marine reptiles, fishes, they were all great at predating and they greatly diversified at that time.
Laura Soul:
So there are lots of different new predators that are trying to eat the urchins?
Camilla Souto:
Exactly, not just the urchins but every survivor after the extinction.
Laura Soul:
Okay.
Camilla Souto:
Some of the sea urchins they're not burrowers, but they evolved really long spines to be better at protecting themselves. Also, they were living between the rocks to protect themselves against fishes and all of those predators that were coming in. You might have seen the species of Diadema which is very painful if you get hurt with it. But most of the sea urchins out there, they're actually burrowers and those burrowers evolved during that Mesozoic marine revolution.
Laura Soul:
Okay. So you have all of these new predators, loads of new species of all different kinds that are trying to eat the urchins and all the other animals. So we get lots of new species of urchin that are taking the strategy of burrowing down into the sediment instead of having spines?
Camilla Souto:
Exactly. They still have spines, they're just much smaller.
Laura Soul:
Right.
Camilla Souto:
So there are a lot of those urchins, but that transition to burrowing the sediment took millions and millions of years. So there was a very slow evolution towards those body shapes that allow you to burrow in the sediment. All right, so I have another question for you. So I have a type of sea urchin here on the left that I'm going to call it the regular, the type A and the sea urchins on the right. Which one of the two types do you think is better at burrowing and why would you think that?
Laura Soul:
All right, so everyone tell us in the chat. Type A or type B, which one is the better burrower and why do you think it would be better at burrowing? It's a bit mixed, the answers so far. We've got quite a few B's, some A's sprinkled in there. Right. "Type B because it's flatter." "Type B, it doesn't have the parts that stick out." Lots of people saying B still, I think we've got a general consensus for B. Is that right, Camilla?
Camilla Souto:
Awesome, you're all correct. Yes. So having a flattened body without those big spines sticking out is much better if you want to burrow in the sediment. But burrowing the sediment doesn't only require you to have a flattened body, it also require many modifications to help you do your body functions. So what would be hard to do if you were living burrowed in the sediment?
Laura Soul:
Okay, so this is the next question. All right. So you've done a great job thinking like scientists with figuring out that previous question Camilla asked you, let's see if you can do it again. If you live buried in the sand what would be harder for you to do than if you live on the surface of the sand? What's going to be more difficult? Getting food, eating. Someone said catching food, finding a mate, breathing, getting food and oxygen, moving. It would be hard to eat, breathing, moving quickly, getting food. Yeah, great. Staying alive. Yeah, definitely. Okay. So everybody's kind of saying things like eating and breathing, staying away from predators and having no food. Are those kind of along the right lines Camilla?
Camilla Souto:
Yeah, they're perfect. They're thinking exactly like scientists. So when you realize a sea urchin is living inside of the sediment you think of all of those questions and you need to figure it out how they do all of those functions. So the first one I'm going to talk about is breathing as you mentioned there. So the regular sea urchins, which are the ones on the left. So they live above the sediment. They have gills close to their mouth, so they use those gills to breathe. But also most of their breathing comes from tubes that come out of these spores here on the side of the body. So these spores goes from the top of the body, here you're looking at the sea urchin from the top to the bottom of the body and we call these tube feet. They have many different functions in these urchins and one of them is for breathing. But if you're living inside of the sediment it's much harder for you to breathe, right? So these urchins on the right, which are the burrowers, here is a sand dollar.
They evolved specialized tube feet, they're only used for breathing. So they restricted those tube feet to the top of the body. So the body that is closer to the surface, right? And these tubed feet are specialized for breathing. So they're very efficient to breathe and because this structure looks like a flower, they're called petals. So that's one way that these sea urchins found out to breathe inside of the sediment.
Laura Soul:
So they have their little tube feet on top of their body and they stick them up to breathe?
Camilla Souto:
They stick them up, they're very small these ones and they look like an empty bag.
Laura Soul:
Okay.
Camilla Souto:
Transparent empty bag and they use it to breathe. Another function that I haven't heard you talking about is pooping. So how would you poop if you are living inside of the sediment? So the regular sea urchins, they have their butthole on the top of their body and why is it good to be there? So if you poo on top of your body, the water current will come and take that poo and take it away from your body or if your body is circular those poo are going to fall on the side of your body and it's not going to live on top of you. But if you have a flattened body, if you poo on top of your body the poo is going to sit on there for a long time. Right? Especially if you're burrowed and there's no water current taking your poo away from you, especially that the poo will be on top of your breathing structure.
So imagine your poo, your nose and you're trying to breathe it will not be good.
Laura Soul:
Yeah, that doesn't seem good at all.
Camilla Souto:
It's not pleasant. So I have another question for you. If you have a body that is flattened with breezing structures on the top, where would you want to have your butthole?
Laura Soul:
All right, that's the next question. You don't want it where your mouth is, where would it be? Okay, some people are saying bottom, bottom, top. Well I think we don't want it on the top because we don't want it to go up our nose. All right, the side, quite a few people saying the side, under, away from me, on your back, on the side. So I think we've got answers from all around the-
Camilla Souto:
All around.
Laura Soul:
What's the actual answer?
Camilla Souto:
So in front of the body wouldn't be very nice because the urchin moves forward. So you would roll over on top of your poo and that wouldn't be interesting. On the sides I believe it could be okay, but in case of the sea urchins we can see that the butthole is on the back of their body. So away from the top, so away from their breathing structures and all the way to the top such that the urchin moves forward and the poo is left behind.
Laura Soul:
Is that one that we are looking at there a fossil sea urchin?
Camilla Souto:
This one is a fossil sea urchin and we can find many different fossils throughout millions of years and you can see that movement of the butthole from here to there. So some urchins have it here, here, and you can see that nice transition that happened throughout evolution to move the butthole to the back of the body of these urchins.
Laura Soul:
That's a really cool way that fossils tell us how evolution happened.
Camilla Souto:
Yeah, it's really cool. The butthole on the bottom of the body wouldn't be very interesting because the mouth of the sea urchin is located there. So here you're looking at the sea urchin, now flip to the other side so you're looking at the mouth. So the mouth is here in the middle and notice that they have these white structures here, they're actually teeth. Sea urchin teeth and they use those teeth to eat algae and they use it to eat on dead animals and they also use it to make holes in rocks. So you probably have seen sea urchins living inside of the rocks. So they use these teeth to make those holes. The burrowing sea urchins, they completely lost those teeth. They're not eating algae anymore, they're not burrowing in rocks, they are eating sediment. So they live inside of the sediment, it's much easier if they gulp the sediment and remove the tiny organisms that live inside of the sediment. So here you're seeing the mouth in the middle. So this hole here is the mouth, and notice there are many spines around the mouth.
So they use those spines to select the sediment they're putting into their bodies and I told you before that the sea urchin have different tube feet for different functions. For example, the tube feet that they use for breathing. Here, they have tube feet specialized for eating and they're placing these holes here and they use those tube feet to pick up the sediment. Bring it to the spines, and they use the spines to choose the grains that they want to eat. In addition to different kinds of tube feet, they have different kind of spines. So I have three spines here that I drew myself trying to learn with Karma and Laura last week and I'd like you to choose which type of spine do you think they would use to eat. Which one of these three?
Laura Soul:
Okay. So you have kind of come up with the idea that it would be difficult to eat if you live in the sediment and they use one of these three types of spine to kind of scoop the sediment into their mouth like tiny chopsticks. All right, answers are coming in. What does everyone think? Spatula-shaped one on the left, three long one. We've got some variable answers, but most people seem to be saying the curved one, the second one. We've got lots of number twos.
Camilla Souto:
Awesome, exactly. The one that kind of looks like a spoon. Yes. So they use those curved spines which are all over your mouth to bring the sediment to their bodies. Very good. So now I'm going to talk about the other two types of spines that I illustrated here. So what are they used for? So sometimes you find that urchin at the beach and you're probably going to see it that it has no spines left. Because when the urchin dies that soft tissue that holds the spine to this structure here, that is called a tubercle it decomposes and their spines fell off.
But when we find the body of the urchin here without the spines, we can use these tubercles to analyze if the spines were big or small, if they were abundant or not. So you can see here that this urchin has really big tubercles compared to this sea urchin here that have tiny tubercles. Also, this one here have many more tubercles compared to this one here. So we can say that the urchin on the left has large and fewer spines, and the urchin on the right has small and numerous spines.
Laura Soul:
Is that how we know about fossils as well?
Camilla Souto:
Exactly. I have a picture of a fossil coming up and I'll show you. So here regarding those two types of spines, this is still a living organism. So here you can see on the left still looking at those tubercles you can notice that the tubercles here are smaller than the two tubercles on the bottom of the body. Right? So here on the top of the body they have small tubercles, they are very thick on the top and those spines are protecting the urchin from being collapsed by the sediment. It's also avoiding that those sand grains fall on the breathing structures. On the other hand, in the bottom of the sea urchin you find these big tubercles which holds long spines that they use to burrow in the sediment and notice also there's a lot of space here. So there are fewer spines because they need space to move around to help the sea urchin to burrow. So notice that the sea urchins had to evolve a lot of different features to be able to live inside of the sediment.
Laura Soul:
So they really are using spines for lots of different things then?
Camilla Souto:
Lots of different things. They're very creative in building up their spines which is super cool, and here is a fossil. So fossil species as you mentioned before, we do not find fossils with spine, we've never found one. But we can tell how the sea urchin lived based on those tubercles that I mentioned before. So here you can see that on the top of their body there's two small tubercles and they have large tubercles on the bottom of their body. So we can infer that they had small spines in the top, large spines in the bottom, therefore they were most likely burrowing like the living sea urchins are doing. So that's pretty cool, and that happened during that time in the Mesozoic marine revolution. So these fossils are very old, they're millions of years old. One last thing is that they have a different function for these spines on the top of their body that a small group of sea urchins evolved and I'd like you to try to guess what they're used for.
So there's this yellow patch here on top of this urchin and try to think about what is this and what these spines are being used for.
Laura Soul:
Okay, this is our last question for you viewers. So take a look at this, this is a sea urchin. It's got those little spines that we've just been talking about and you need to try and figure out what do you think all that yellow stuff is on the sea urchin. Okay. Some people are saying to grip stuff, camouflage, protection, poison. Poison's coming up quite a lot. Camouflage, food, pee, we were talking about poo back there, sediment. See, this is interesting. People are coming up with lots of great suggestions, but I'm not sure anyone's got the right one yet. What are they?
Camilla Souto:
So I analyzed this specimen myself and when I looked at it I counted about actually more than 100 babies on top of the sea urchin. So this is a mama sea urchin that is using those spines to protect their babies. So there's more than 100 here of tiny sea urchins of sea urchin embryos. So the sea urchins settle there and they grow and when they're ready to go to the sediment mama lets them just go and live their life on their own.
Laura Soul:
That's so cool. All those tiny little babies, it's really cute.
Camilla Souto:
Tiny little babies.
Laura Soul:
But they really do use their spines for everything, right? We talked about how they eat and how they burrow and how they protect themselves and how they keep their babies safe.
Camilla Souto:
Yes.
Laura Soul:
All right, great. So we actually had a whole load of questions that came in from our viewers.
Camilla Souto:
Awesome.
Laura Soul:
If you want to answer some of them. So the first one that I've got, I think is a great question about fossils. So Kate would like to know, because it's so much harder for soft material to fossilize than for hard things like bone. Is it rare to find echinoderm fossils?
Camilla Souto:
Actually it's very easy to find echinoderm fossils. Because their body is made up of the skeleton and I didn't mention before, but these are made of calcium carbonate which is a very hard skeleton that they have around their bodies. They're very easily preserved and especially for these sea urchins that already live burrowing the sediment, when they die they die inside of the sediment and they're already burrowed they're very easy to be preserved.
Laura Soul:
Okay. So we were talking about fossil sea urchins and living sea urchins. Are there types of fossil sea urchins that we found that definitely aren't living anymore?
Camilla Souto:
Yes. Actually most of the fossils in this group, they are completely gone and there are very few species living of this group that I studied. There's only about 30 living species and most of them are 400 or more fossils that we find in the collections.
Laura Soul:
When were the very first sea urchins? We were talking about the Mesozoic marine revolution, that was the same time as the dinosaurs. But were there sea urchins even before that?
Camilla Souto:
Sea urchins they're not as old as the specimens, the species that's caught studies. So let me try to pull out here my slide to show you how old they are. So can you see my slide?
Laura Soul:
Yes.
Camilla Souto:
So sea urchins, they date from the Ordovician. So this period here more than 400 million years ago is the age of the oldest sea urchin.
Laura Soul:
Wow.
Camilla Souto:
Echinoderms, they're much older than that. Very old, yeah.
Laura Soul:
Okay. So that's like way before the dinosaurs? Very old-
Camilla Souto:
Way before the dinosaurs. But the burrowing ones they're all from the Mesozoic onwards.
Laura Soul:
Okay. We have had a few more questions about you and your job, if you don't mind answering those as well. So one of them is how long does it take to become a marine paleobiologist?
Camilla Souto:
So it takes a long time. I mean if you consider that at four years old when I was running around the beaches and looking for crabs and sand dollars, that is at the beginning of being a marine paleobiologist. But then you go to college. So I did my undergraduate studies in biology and then I did a master's in zoology. A master's is required in some places but not always and you move on to a Ph.D. that you study paleontology. So you can study biology or geology. Both are different ways that you can reach paleobiology and then you can choose to study marine organisms or terrestrial organisms. It's up to you what you want to go to.
Laura Soul:
Yeah. So I think you did biology, right? Whereas I did geology when I became a paleontologist.
Camilla Souto:
Yeah. The diversity is very nice.
Laura Soul:
Yeah. Okay. Then we already sort of talked about why you liked your job, but someone would like to know what is your favorite part out of all of the different parts of your job?
Camilla Souto:
My favorite part? I'm really bad at choosing favorites. I love interacting with all of you, it's very exciting and it's really cool to share the discoveries we make with all of you and you hearing all of your questions it actually drive a lot of our research. So that's going to be my favorite for now.
Laura Soul:
Yeah. Talking to you all is a great part of our jobs. All right, so we'll go back to the sea urchin questions. Somebody wants to know are urchins asexual and how are they fertilized? How do they reproduce?
Camilla Souto:
So urchins, they sexually reproduce by releasing ... So the males release gametes in the water and the females release gametes in the water and those gametes get together and make an embryo. So they're sexually reproducing. I'm not aware of an asexually reproducing sea urchin, although there are echinoderms that they can reproduce asexually. Like the sea cucumbers for example, some of them do.
Laura Soul:
Okay. We were talking all through the program about how you use both living species and fossil species to kind of understand the whole group and they both inform each other. I think all the species that you've discovered at the beginning were living, right? How many of them were there?
Camilla Souto:
Seven species.
Laura Soul:
It seems like quite a lot, that's a good record.
Camilla Souto:
It's exciting.
Laura Soul:
Okay. Well, so someone has asked where is the sea urchin's DNA?
Camilla Souto:
Where?
Laura Soul:
Yeah.
Camilla Souto:
So the DNA lies inside of the cells, so in the nucleus of the cell they have their strands of DNA. When we collect the DNA we get usually soft tissue and we make a lot of preparations to extract the DNA from the cell.
Laura Soul:
So finding DNA from sea urchins is a thing that you do?
Camilla Souto:
Yes. It's something that I do for the living ones because the fossil ones the DNA has been degraded for a long time, it's not present anymore.
Laura Soul:
Okay. Someone would like to know, how many different species are there of sea urchins living today?
Camilla Souto:
There are almost 1,000 species and a great proportion of them, way more than half are burrowing sea urchins.
Laura Soul:
Okay, so there are lots of them. Then I think something people might be familiar with are sand dollars, right? Are sand dollars sea urchins? Are they dead sea urchins? How do those relate to what we were looking at today?
Camilla Souto:
Sand dollars, they are sea urchins. So the scientific name that we call the group of the sea urchin is called echinoids. So echinoids are the sea urchins, they are the one within long spines. They are the sand dollars, they are the cassiduloids, which is the group that I study. They are heart urchins, which are also burrowing. So sand dollars is a type of echinoid that they're not burrowing completely anymore, but they're still living on top of the sediment. I've heard the people saying that sand dollars are mothers of the sea stars because the petals in the top, those breathing structures they look like a sea star. So they thought the sea stars would be born from that structure, but those are the breathing structures of the sand dollars.
Laura Soul:
Okay. So they're completely separate types of animals, sea stars and sea urchins?
Camilla Souto:
Closely related but different kind of animals.
Laura Soul:
Okay. I think we've got about time for one more question. So I think I've heard that some sea urchins are poisonous. Is that true? Are they all poisonous? How does that work?
Camilla Souto:
They're not all poisonous. Can I show one slide?
Laura Soul:
Yeah.
Camilla Souto:
All right, let's see here because I actually separate a slide for you. So there are few species that are poisonous. So these species here for example, the flower urchins they have a structure with a toxin that can be quite harmful to humans. But there are not a lot of species that are poisonous to us. But that species of the Diadema that I showed you before, they have a very slight toxin. Sometimes you can be pierced by these spines and you think there's a lot of poison because it hurts a lot. But these spines they have these type of barbs that stick to your skin, it hurts a lot. So these are two pieces of sea urchins that are more dangerous to you, but in general they're not very harmful. You'll hurt, you make a hole in your foot, but it's not going to be that bad.
Laura Soul:
Okay. So sea urchins are really our friends. Okay. All right. Well, so that was really exciting. Thanks so much for telling us all about all the different ways that sea urchins live in the sediment and have evolved. Also, thank you to everyone who was watching and sent in all those great questions for us.
Camilla Souto:
Thank you, it was very fun to be here.
Maggy Benson:
Yeah. Thank you so much Camilla, it's been so interesting learning about sea urchins. If some of our friends want to learn more about sea urchins, where can they go for more information?
Camilla Souto:
So there's a very cool blog written by one of the Smithsonian's researchers, Chris Mah, and is the kind of blog that Maggy will post for you. You can learn more about my research on Twitter. So it's C-O-U-T-0, because C. Souto was already taken.
Maggy Benson:
Thank you so much Camilla, and thank you so much Laura for teaching us all about echinoderms, sea urchins specifically, and how we can learn about sea urchins from the past by understanding the ones that are living today. We have a lot of comments in the chat about people who are now inspired to see urchins and go to the beach so well done. Viewers thank you so much for all of your great questions, you're all clearly thinking like scientists and that's really exciting. We love having you here on Fossil Friday. While you're exiting, if you can fill out our post program survey. It'll show up in the Zoom browser window once you exit. If you can fill out that survey, we'd be really appreciative and I also want to tell everyone that we do have another drawing workshop tomorrow at 11:00 AM. I shared one of my drafts, we have paleoartists who are coming and teaching us how to draw dinosaurs. This is a Ceratosaurus, though a little incomplete. Tomorrow we're learning how to draw a Triceratops.
So come join us tomorrow at 11:00 AM. If you're looking for the link, you can see it right here on my screen for more information about tomorrow's program. Also, next week we will be back. On Thursday we'll be exploring deep see octopods and squids, and we'll be back here on Fossil Friday with Dr. Brianna Pobiner who's going to teach us a little bit about paleoanthropology. So we hope you can join us then. Thank you all so much for joining us here on Fossil Friday. Thank you, Laura, thank you Camilla. Thank you Scott, thank you Rich, wonderful questions everyone. Have a great weekend.
Laura Soul:
Thanks. Bye everyone.
