Jellyfish Live!
Aired May 18, 2020
Christian:
Hello everyone. My name is Christian. I work at the Smithsonian National Museum of Natural History. I'm coming to you live from my home in D.C. In just a moment, we'll be joining Dr. Allen Collins from inside the Natural History Museum. The museum is closed, but he's got special permission to go in, to feed the animals in the Invertebrate Zoology Department's Aqua Room. While people are still joining, I want to let you know that this program is going to be about 30 minutes. Allen's got three stops planned, where he's going to show off some of the live animals, and talk about jellyfish, and biodiversity of jellyfish, and their life cycle. After each stop, we will pause and take a couple of questions. To submit a question, you should have a Q&A button somewhere on your screen. It's the button with the two speech bubbles. If you put a question in there, we will try to get to it. We won't be able to get to all of your questions today, but we'll do our best to get as many as we can.
Allen Collins:
... Good morning. I'm Allen, and as Christian told you, I'm a curator here in the Smithsonian National Museum of Natural History in the Department of Invertebrate Zoology. And a curator is basically someone who cares for the collections and studies them. I actually work for NOAA Fisheries, and I'm part of a small lab that's embedded within the Smithsonian. And there are several scientists like that here working in the Smithsonian and that's because our federal agencies understand the extreme value that biodiversity has.
The federal agency scientists who work here in the museum, do collections-based research on questions related to biodiversity. And in my case, I'm an expert in sponges to a lesser degree, and then the jellyfish group. We have in Invertebrate Zoology, about 50 million collections, and these are actually laid out on about 15 miles or 25 kilometers of shelving, such as this coral here, this is Acropora cervicornis, or this glass sponge here from the deep sea off the coast of North Carolina where it part of deep sea reef communities. But I'm here because we also have a few animals that we keep alive and so I'm going to show you some of those.
The name of the facility that we have here in Invertebrate Zoology is called the Aqua Room. Here we have a ... You can see it's a smallish room, and so I'll just take you over here in this direction. Before going to the live ones, here are few more examples of the different jellyfish groups. As I said, I'm an expert in diversity, and what you see here is one of the group that we typically think of as jellyfish, this is Scyphozoa, and this is a cannonball jelly that's actually edible by humans. Here's a jar full of stalk jellies.
They're very unusual. They live on the bottom. They live mostly in cold waters, distributed anti-tropically, mostly. And then of course, the box jellies. These are some of my favorites. They're well known relatively because some species of box jellies can hurt a human quite badly, some are lethal. The most venomous known animal in the world is probably a box jellyfish, Chironex. The big group of jellies that we don't spend as much time thinking about includes is called Hydrozoa. And the Hydromedusae, there are very very many kinds. There are way more kinds of Hydromedusae than all the others. Stepping back from there, let's look at some of the live animals. I'm hoping you can see in here, this is a sea nettle, and this is common to people. A lot of people have experiences with this. This is common locally here in the D.C. area in the Chesapeake Bay.
It's called Chrysaora chesapeakei, and it stings some people. It's not a particularly bad stinger, but it's not pleasant if you're in the water and you get stung by it. I'm just going to go past our little quick life-cycle diagram here. The medusa stage of the jellyfish stage, that is the part that swims around in the water most of the time and is the adult stage. So, they produce eggs and sperm, and when they shed those eggs and sperm, or when the eggs and sperm meet, they make a small larva called a planula that settles on the bottom, makes a small polyp. And these polyps then asexually reproduce quite a bit ... each other so they make more and more polyps and each polyp can generate one or more medusae. That's your basic life cycle. I wanted to stop here, and look at what's perhaps the most familiar jellyfish to most people.
This is called Aurelia or the moon jelly. It's interesting to think about how these animals are swimming around. I see a lot of the public come into the museum and I ask them how jellyfish swim. And they often say, using jet propulsion. And it's true that some jellies do squeeze out water like a jet but a lot of the larger ones, in fact, nearly all of the larger ones move in a different way. They're actually paddling. You can see their bodies all the way around the outside and this actually pushes the water and food into where they're filtering that food out and catching it. I've fed these guys some brine shrimp earlier in the morning, and you can see that brine shrimp in those little pockets on the top of the body that's inside its stomach. It's caught all those brine shrimp and then moved them into the body.
That's one way of jelly's going. Now I want to show you a little bit of a different shape. You can see up here, on this diagram right here, this is a jellyfish, has a small constriction here, it's much more elongated. And this is the kind of jellyfish that moves by more like jet propulsion. One other thing you might be interested to notice about this animal is that it has these weird branching tentacles. And that's the subject of the day, that is when jellyfish don't swim. Because a lot of jellyfish spend a lot of their time not swimming in the water and it's not something we think about too often. So, Christian.
Christian:
[inaudible 00:07:54] do all jellyfish have tentacles? Is a question we've got from Isla.
Allen Collins:
That's a good question. No, they don't. The Stomolophus, that whole group is called Rhizostomeae, and they do not have tentacles. Anymore [inaudible 00:08:13] come in?
Christian:
I've got a couple more. How big do box jellies get?
Allen Collins:
The largest box jellyfish is about the size of my head.
Christian:
Nice.
Allen Collins:
That's Chironex, and that's the one that's capable of killing an adult human in about five minutes if you get a sufficient amount of sting.
Christian:
Oh, dang. But not all jellyfish are poisonous, right? That's a question that we've got in here, as well.
Allen Collins:
Well, poisonous is if you eat them and they would poison you. They're venomous. They all have stinging capsules, and they're all capable of delivering that venom to their prey. But what happens is if we encounter them, they would also sting us. But the vast majority of jellyfish don't bother us because their stinging capsules are so small that they don't penetrate very far into our skin. The ones that really bother us tend to have very large stinging capsules.
Christian:
So, they all can sting, but they don't all hurt us?
Allen Collins:
Yes, indeed. I like to tell visitors to the museum that if they've been in the ocean, they've been stung, but most of them don't hurt.
Christian:
Oh, okay. Here's a really good question that I like a lot. Shannon would like to know, do you name the jellyfish?
Allen Collins:
Rarely. We've had this room going for three or four years. Four, yeah, a good four years now. And when we keep most of the animals at the polyp stage, because they demand less food, they don't have a high metabolism, much easier to keep. When those polyps would make medusae at the very beginning, we had very few medusae around, and indeed we would give them names at that point, but I don't do that so often. This room usually has a lot of interns, and students, and postdocs working in it, and so we have a lot of fun with them, and sometimes we do name them.
Christian:
That's great. All right, I'm going to let you move on to your next stop.
Allen Collins:
Sure. So, now what I'm going to show you is ... I showed you in those jars a lot of jellyfish that are relatively large, and that's because they're easy to see. But most jellyfish are kind of small. And in fact, many of the ones that we rear are small. What I have here is a microscope. It's connected to a camera, and this got a live view over here on this monitor. And so what I'm going to do is ... Oh, there goes a little jelly. Let's focus in on a couple of the jellies in this jar. And I know we've got some feedback. I'm going to try to see if I can ... You going to bear with me while I find them. Whoop, there goes one.
Okay, settle down. Oh no, there's a larger one. You see this jellyfish, this is one called Scolionema, which we raised here. And this one is resting right now on the bottom. I'm zoomed all the way out, it's about a centimeter across from here to here. And you can see this is its mouth region. It has canals. These are its gonads developing. And then all the way around the outside, you see the beginnings of their tentacles. And it has its tentacles all spread out. Now, if we move and try to look at the ends of some of these tentacles. Let's see here. I'm going to zoom in a little bit and give it some more light.
Yep, there we go. You see how it has these little knobs at the end of the tentacle? Those knobs are actually sticky pads. This jellyfish is adapted for sitting on the bottom. It is capable of swimming, but it spends a lot of its time on the bottom. It will swim up into the water column, catch its prey, and then fall back down to the bottom. And then there's some other ones. Let's see. I'm going to switch over to another species. That was Scolionema. And this is another one. All those little dots going by are jellies.
And this is the jellyfish Cladonema, which we've been rearing here in the lab. I'm going to focus in on one. This one is lying on its side. Well, now it's on its top. Now it's on its bottom. It moves around. Hopefully, the ... Oh, it ran away. That's not too uncommon for these guys, so they can swim but these also spend a lot of time sitting on the bottom. I wonder if anyone has any ideas why some of these jellies would sit on the bottom, because I don't know.
But it also has special adaptations to being on the bottom. This is the one that was in that diagram, and it has branching tentacles. Trying to get it on the side a little bit where we can see and zoom in. Not sure how easy this is to see. And it has tentacles that go down, and they have a sticky pad on them so they branch, and they stick to the bottom. And then they have tentacles that they hold up into the water, those are the ones that are longer. You can see them up in the water there. They use those to catch prey so they're sort of feeding tentacles, specialized tentacles for feeding, and then tentacles they use to stick on to the bottom.
We'll leave the microscope for a tiny bit.
Christian:
All right, I've got some more questions for you.
Allen Collins:
It's a good time for questions.
Christian:
Great. While we were looking at some things under the microscope, can you tell us a bit about the smallest jellyfish? We've got a couple questions about what the smallest jellyfish is.
Allen Collins:
Yeah. There are several species that have very tiny, tiny jellyfish as part of their life cycle. And the one I think of usually first is an animal that you don't usually think of as a jellyfish. Any of you have been swimming in tropical waters have probably been told to keep your eye out for the fire coral, because fire coral can create a bad sting. That's actually in the jellyfish group. It's Hydrozoa, and the name of the genus is Millepora. And the Millepora animal has a big colony. It's calcium carbonate. It looks like a coral, and that's why it's called a fire coral. And it produces though a little tiny jellyfish that's less than about a half a millimeter. It's tiny. Basically, it just carries the gonads. So, it's just a reproductive structure. It's a very short-lived. There are several species that create medusae that are that tiny, less than one millimeter size range.
Christian:
Great. Andre and Deloque from Bali both have some questions about the ecological roles of jellyfish. Why are they [inaudible 00:16:43]? And if you found jellyfish abundant in the water, would that be a sign that other things might be abundant too?
Allen Collins:
The jellies themselves are often encountered episodically. They're tend to show up in large numbers, large groups, when the water column is ripe and rich for them, the conditions are rich for them. They show up in a lot of numbers. And then at other times you don't see them. For instance, this is a question from Bali, the waters in Bali around Indonesia are extremely rich in biodiversity, but only sometimes will there be lots of jellyfish visible in the water. There will always be lots of tiny guys, and the diversity is quite high there, yes. The general diversity of jellies follows the diversity of most life where it'll be richest in the tropics. That means the most different kinds. And there was a question about their role in the ecosystem?
Christian:
Their ecological roles, what they might be?
Allen Collins:
Yeah. Well, they're predators, and when they're large, which some species are, they can be pretty dominant top predators, but they're also a prey. There are some really well-known organisms that primarily feed on jellies. For instance, the Mola mola, the sunfish is a well-known jellyfish eater, as are some of the sea turtles, eat a lot of jellies. But it turns out that by using more sophisticated techniques, by looking at DNA in the guts of different kinds of fish, or looking at isotopes and stuff, it turns out that jellies are in a lot of different fishes' diets, even ones that we didn't think were eating jellies. They're very important as both food and as predators. Some jellies will eat other jellies. That nettle over there that I showed you, it eats a different kind of gelatinous animal called Ctenophore quite voraciously in the Chesapeake system. They're playing really important roles basically.
Christian:
That's great. I do want to say, we've seen some people mentioning that they're having some issue with the sound coming in and out, so we apologize and thank you for staying with us with our technical difficulties. All right. Did you want to [inaudible 00:19:27]
Allen Collins:
Sure, I can go, or we can take more questions. Whatever you'd like.
Christian:
If you want to head to the next stop, then I'm going to [inaudible 00:19:37]
Allen Collins:
[inaudible 00:19:37] a little bit of [inaudible 00:19:39]. It's just a quick shout out to my interns and folks, I miss you all. I wish you were here in the museum. I also wanted to focus on this particular intern, Kelly Walls, who was with me this past summer. She's terrific. She's there holding the jelly wand. She conducted an analysis of when jellyfish don't swim. And we figured out through her hard work that the evolution of not swimming and being on the bottom has happened at least six times within a jellyfish independently of each other.
Christian:
Actually on that subject, can you tell us a little bit while you walk into the next place about your career path, how someone becomes a jellyfish researcher?
Allen Collins:
Yeah. My career path is very convoluted, but basically it had to do with ... The way I wound up here is I started as an economist, mathematician, was working my way towards an MBA when I decided that I was more interested in biology. I got interested in historical biology, evolutionary biology, started working on paleontology type questions for a Ph.D. And by the time I had finished my Ph.D., I had collected so many jellyfish that I had become just fascinated with everything about them. And I basically didn't know where I was going, but I was working on papers. I was putting most of my effort into writing papers about jellyfish diversity at that time of my career. And then just lucked into the most amazing job ever.
So, follow your passion basically, if you've got it. Now we're into the other room in the Aqua Room. And here we have some incubators because of course, different jelly polyps are going to like different temperatures to be kept alive at. All these dishes that you can see have different kinds of jellyfish polyps in them. What I wanted to focus on in this room is this particular species here, which is another bottom dwelling animal. Although you can see one swimming there, you see it? You don't see that too often, that's the Cassiopea, a small one, swimming around. And several of these, what we call Upside-down jellyfish on the bottom.
This was one of the first species that we kept. It doesn't require, like the first tanks that we were looking at, the constant moving water around in a circle because it spends its time living on the bottom. In nature, species of Cassiopea, there's about maybe a dozen of them, or 10 or so different species. They live all the way around the world in warm waters, shallow waters. And this is the way they live, on the bottom with their tentacles, or they're not their tentacles, they're their arms technically, up facing away from the bottom. The bell of the jellyfish, the typical part that's used for swimming is on the bottom and it pulses, and it's still doing what other jellyfish are doing, it's pushing the water through this frilly part. And those frilly part are catching organisms. It gets a lot of its nutrition by catching organisms, but it gets its nutrition in another way.
And that's by sitting on the bottom exposing its body to bright light. And it has a tight symbiosis with an algae, a Symbiodinium alga, that lives inside its tissues and it's photosynthesizing, the alga is, and then providing sugars for the metabolism of the jellyfish. Or just a really great example of how tightly life can be linked. This is very similar to what you see in corals, in many other different cnidarian groups, including in the several different kinds of jellies. Often people will ask me, why are they upside-down? And the simple answer is that they sit there exposing their tissues to the light so that the algae are able to photosynthesize. But the truth is, that there are several other jellyfish species that have this same type of symbiosis, and they provide access to the algae, access to the light a different way. They'll maybe swim near the surface back and forth, and stuff like that. Any questions popped up here, Christian, that I could answer?
Christian:
Yeah, we have a lot ... Many, many great questions. Which again, thank you all for asking all of these questions. We're not going to get to all of them. Let's see, do you want to talk a little bit about this one and then we can do a rapid fire of some yes and nos?
Allen Collins:
Sure, sure. However, you'd like to do it. This is a 55-gallon ... what's that about 200-liter tank that has some larger animals in it. You can see this nice Plexaurella octocoral, that's quite large and easy to see. It also has all these algae in there. I think you can see this anemone growing here. The anemone, and this octocoral, and these little round dots, which are small axial worms, all of these species also have algae in their tissues. And they have this symbiotic relationship with the algae, where the algae is photosynthesizing, providing nutrients to the organism, and the organism is ... When it catches food, it actually provides some nutrients to the algae that the algae needs.
And this tank is like a bit of field work. The Scolionema, the first jellyfish I showed you under the microscope, that was actually discovered on a polyp in here by a woman whose name is Rebecca Helm. And she was a postdoc here for a year, really great year. And she found that on the wall. And then we raised that polyp, until now we have many, many medusae growing, and we've sequenced its genome, and we're trying to make it available as a potential animal for study for different labs.
Christian:
I've got a question, are the jellies born with the symbiotic algae, or do they acquire them after birth?
Allen Collins:
Oh gosh, that's a good question. I should know this, but my mind is blanking a tiny bit. They can definitely take the algae in from the outside, but I believe that the algae come through. The algae are in there, little larvae. They must come through the maternal line with the eggs. The algae ... No, I'm not thinking straight. These animals actually brood their larvae, so they have access to the algae right from the very beginning.
Christian:
Alrighty. Are you ready for some rapid fires?
Allen Collins:
Yeah. [inaudible 00:27:26]
Christian:
Are there [inaudible 00:27:30]?
Allen Collins:
One more time, that broke up.
Christian:
Are there jellyfish pools?
Allen Collins:
I'm sorry, jellyfish what?
Christian:
Pools, P-O-O-L-S.
Allen Collins:
Pools. Well, there are jellyfish lakes, there are freshwater lakes that have jellyfish and there are saline, saltwater lakes that have jellyfish. But I don't know of any ... You could have them in a pool, in a big trough if you have the right water in them, you could raise them that way.
Christian:
Can jellyfish live in deep water?
Allen Collins:
They definitely do live in the ... They're in all parts of the ocean. They live in very deep waters, thousands of meters down.
Christian:
Great, are there lots of jellyfish and is there great genetic diversity?
Allen Collins:
The genetic diversity's quite high in jellyfish. And that's because they've been diversifying for a long period of time, perhaps 500, 600 million years. And yes, there are quite a number of different kinds. The group to which all these animals belong is called Medusozoa, and we know about 3,600 different Medusozoan species. And there are probably at least that many still to be discovered.
Christian:
Have you found a new species of jellyfish?
Allen Collins:
Yeah, quite a few. Quite a few. I've named over the years, so yes. And most of the time that we go to the field, you could probably expect to find a new species.
Christian:
And do jellyfish sleep?
Allen Collins:
Well, it's a good question. There was a study done on this species here, this Cassiopea. The study was looking at whether the animal displayed sleep-like characteristics. They do have a cycle, as you might expect, since they live in bright light, and have the day and night. And they have algae that are going to be active during only one part of that cycle. They used a criterion by which they define sleep, and they showed that a lot of the things that you would expect to be indicative of sleep are shown by these jellyfish. If you don't let them sleep, they get tired, things like that so they actually, if you don't let them go through the day-night cycle like that. I would say some people think they sleep. There are some people that would disagree a little bit with that. And that's the only species that's been looked at. There are many other species that we need to investigate to find out if jellyfish generally sleep.
Christian:
All right, last one and then we should probably wrap it up. [inaudible 00:30:30] jellyfish?
Allen Collins:
One more time?
Christian:
Have you eaten jellyfish?
Allen Collins:
I have indeed eaten jellyfish. Jellyfish in a salad, couple times and it's actually quite delicious. Well, it's as delicious as the sauces anyway that you put on it. What's really interesting about it though, is its texture because it's, believe it or not, a little bit crunchy. It has that rubbery texture, it just starts to give, but then it cracks. It has a crunchiness that's unexpected, and that actually makes it fun to eat jellies. I want to just say before we run out of here, that Rebecca Helm is going to be a guest with us next week, and she's an expert in how jellyfish make their bodies.
Christian:
That's wonderful.
Allen Collins:
Two weeks from now.
Christian:
[inaudible 00:31:22] ask you to give us a hint at what's coming next. Because we're doing more of these in the future.
Allen Collins:
Yeah, right now we're going to do them every two weeks at 11:00 AM and we're going to try to concentrate on little different bits of jellyfish biology each time. And what we are going to do next time is have a guest, someone who was working here in this lab, and helped us build up some of the animals, and the capabilities that we have in this lab. Her name is Rebecca Helm, and she's a fantastic educator, and scientist, and she knows a lot about how jellyfish make their bodies, how they develop, and the evolution of that development. And so I think that's what we'll be focusing on in two weeks from now. And after that we got to figure it out.
Christian:
If anyone would like to stick around for a couple more minutes, we can try to squeeze in a few more questions. But before we do that, I just wanted to thank you all for joining us and to let you know that you will be getting a survey at the conclusion of this program that we'd love to get your feedback on. And if you enjoyed this program, like we've said, there's more about jellyfish coming, and there's a lot more on the Natural History Museum website about all sorts of different topics. And if you want to learn more about jellyfish in the ocean, you can visit the ocean portal at ocean.si.edu. All right, so Allen, a couple more questions.
Allen Collins:
Sure.
Christian:
Do jellyfish lose their algal symbionts like corals in coral bleaching?
Allen Collins:
Generally, we don't know for everyone, but it is true that some can lose their algae. You can do it in the lab, for instance. You can deprive them of light and they lose the algae. And then they more or less, if they're in the polyp form, they can live just fine. They can multiply, but they cannot make a medusa stage. The upside-down jellyfishes actually require that algae in order to complete their life cycle to adults. For lot of other species, we just don't know.
Christian:
What are some animals that eat jellyfish?
Allen Collins:
Well, humans, fish and quite a number of crustacean, like organisms called amphipods. They will land on jellyfish and eat the jellyfish slowly. And so then we got turtles, even mallards eat some jellyfish that are up at the surface. Sharks, some kinds of sharks actually eat jellyfish. It's really most of what's out there. And lots of jellies eat other jellies.
Christian:
Here's a local question. Chelsea lives in Maryland where the Patuxent River meets the Chesapeake Bay. Last year they didn't have any sea nettles until September, but this year they're already seeing comb jellies. Does this mean that the Bay is healthier this year?
Allen Collins:
No, that does not mean the Bay is healthier or less healthy this year. That is normal variation. Jellies, when conditions are right, will show up in large numbers. And actually last year there was so much extra runoff in the Chesapeake Bay watershed that the salinity was lower than it is normally for quite a long time. And that prevented the jellyfish from appearing when they normally do. But there's a predictive model that some folks put together, they did what they were supposed to, they showed up when they were supposed to.
Christian:
How did jellyfish perceive their world? We've got a lot of questions about jellyfish eyes and things like that.
Allen Collins:
Yeah, they have a lot of different kinds of senses. The ones that we focus on a lot have to do ... They have organs called statocysts, and those are essentially a ciliated sack with a rock inside. And so when that turns, the rock will fall one way or another. It's a lot like our ears work and they can then tell which way is up. The upside-down jellies, as you imagine, they have to have themselves in the orientation so that their tissues are exposed to the sunlight. They can sense that, and will turn over, and it's their statocysts that they used to sense their orientation.
Other jellies ... Well, lots of jellies also have light sensitivity of various sorts. And that can just be the ability to sense shadows, and light and darkness intensity. And there's even some evidence that if a shadow comes over, some of the animals that have these nematocysts, the stinging cells, that they get them ready to shoot in case they're touched by whatever's going to, maybe a predator is about to bite them. They get them ready, put them on the edge of their bodies because of the shadow coming over top of them. There are also several species, including the Cladonema that we showed, that have eyes with lenses, and that suggests that they're capable of something more like vision. All the box jellies have very complex eyes that include lenses and retinas, and it's quite clear that they have a vision of some sort.
Christian:
All right. And final question, and then I think we should probably wrap it up. What is your favorite jellyfish?
Allen Collins:
One more.
Christian:
What is your favorite jellyfish?
Allen Collins:
My favorite jellyfish. Oh, I love the whole group so much. I really don't have a favorite. They are my favorite.
Christian:
All right. Well, thank you so much Allen, and thank you everyone for joining us. Again, we're going to be having some more of these, so you can head to the museum website to find out more about that. With Rebecca Helm next time.
Allen Collins:
Yeah, two weeks.
Christian:
Two weeks. All right. Bye.
