SciCafe: Amazing Anemones

SciCafe: Amazing Anemones - Transcript

Estefania Rodriguez (Associate Curator, Division of Invertebrate Zoology, American Museum of Natural History):

I'm here today to talk about my research on sea anemones. First thing that I want to say actually is how did you pronounce sea anemones? Well, it's sea ane-mo-nes, not sea anenemes. No. Sea anemones. Easy. Okay, that one's settled.

So, yeah, I study the evolution and diversity of these creatures. And first thing that I'm going to do is introduce you, what are these animals. So, they belong to the phylum Cnidaria. Cnidaria is a group of marine invertebrates that are around 10,000 species. They include jellyfish, sea anemones, corals, sea fans, siphonophores. So, a great variety of animals of morphologically diverse animals. These are very simple animals. They have a tissue level organization, which means that they don't have organs or systems. So, no eyes and yeah, nothing basically. They are a couple layers of a few cells, and in between those they have an extracellular matrix. So, they have epidermis, mesoglea and gastrodermis.

And another thing that is very characteristic of these animals is that they have generation alternation, which means that during their lifetime they go through two different life forms. They can be a polyp or a medusa. The polyp lives in the sea floor. They are basically anchored there. And the jellyfish, or medusa, they go around the column water moving around.

They are all together because they have cnidae. And what is cnidae? Cnidae are cellular products, and they are basically a capsule, with a tubule inside that is full of spines. And when you disturb this animals, these capsules discharge, and they sting you. So, if a jellyfish ever sting you, this is actually what harm you.

So, Cnidaria is composed of two big groups. We have the Medusozoa and the Anthozoa. The Medusozoa are characterized because they have a medusa, or a jellyfish, in their life cycle. But that Anthozoans don't have. They are only a polyp. So, anemone are within Anthozoans. Anthozoans are marine animals. They are sessile. They live in the sea floor. And they are solitary or colonial. They live in every marine environment, and there are around 7,000 species. And, again, this group divides in another two groups: the Octocorallia and the Hexacorallia. And sea anemones belong to the Hexacorallia. Sorry for all this classification, but that's what we do; classify things.

So, hexacorals - what are hexacorals? Hexacorals show amazing diversity of forms. Within hexacorals you have the corals that form the coral reefs that everybody knows.But they can be colonial. They can be solitary. They can be pseudocolonial. They can have skeleton. They can lack skeleton. And they are characterized because they have one of these cnidae that is special for them. It's a sticky one, and they are also characterized, and for that, the name - because they have tentacles in number of six or multiple of six. And, again, they show an amazing variety of forms.

So, now finally I got to sea anemones. Sea anemones are those that belong to the order Actiniaria. That's the scientific name for them. And they are defined as solitary hexacorals that don't have skeleton. There are around 1,200 species. And they live in every marine environment. They live from the really shallow water to the deepest trenches in this world. And I'm talking about 10 kilometers down below the surface. They can also live in the ice. Everywhere that you can think about there is a marine environment, they are going to be there.

So, how is an anemone? Basically, anemones are a hollow sac that has tentacles. And in that has an opening that is the mouth. And then inside that sac, we have radial walls. And in those walls, we have some muscles. Here, you have a longitudinal section of how it would look. And so those lines are those walls I'm talking about. Why am I showing you this? Because actually anemones are very simple - relatively simple. And what we use to differentiate them is all this internal anatomy and those capsules that I was showing you before. So, we rely in all these - yeah, internal characters to identify them.

What do they eat? They eat everything that you can think about. They can be suspension feeders, which means they grab small particles or small animals that are in the water column. And they can also - they are actually opportunistic feeders. So, if whatever they can get to the tentacles and they can hold on to, they will eat. But they also can be primary producers, which means that they can also live just from the light because they can associate, as the corals, with photosynthetic algae. So, they can do anything.

How do they reproduce? Same thing; they can do everything that you can think about. They reproduce asexually. They reproduce sexually. When they reproduce asexually, they can divide this way or this way. They can eat a tentacle and another anemone will come of it. They can be females, males, hermaphrodites, everything. And then also when they do reproduce sexually, they can all throw their eggs to the water column, or they can actually take care of the offspring. In this image, you have an anemone with lots of little anemones around her neck.

So, why are they important? They are important ecologically because, as I said, they are suspension feeders. So, they form part of this community that incorporates the energy in the water column to the rest of the food chain. So, the cows of the sea, if you make that comparison. They are also important because they form part of these very charismatic symbiosis like the clown fish, that I'm sure that everybody knows. Nemo, we love him. But they also form part of this symbiosis with hermit crabs. Hermit crabs grab them and put them on their back to be protected.

They have also economical relevance because they are beautiful and are used in the aquarium trade. And they can be used also as food resources. In some countries, they eat them. They fry them, and they do eat them. And also they are a source for natural products. The toxins that are in these stinging capsules are a potential source for new compounds. And also they can be dangerous, as you can see. This is from an anemone, but same thing the jellyfish- I mean, they are the same group of animals.

So, what do I do with this animals that hopefully you know a little bit about them now? Well, what I do is I study the biodiversity of them, the evolution. And I'm talking today about three main projects that I work on. So, the first of all of all of these three is going to be diversity. So, we know very little about this animal. It's incredible because they are in every marine environment, but somehow everybody ignores them. This might be because there only around five specialists that are able to identify these animals properly in the whole world, and this includes students also. So, there is a great necessity for compiling inventories. We don't know what is in there, and also we need to describe new species and new families and higher up, too, and to do redescriptions because a lot of studies were done a long time ago. And they don't meet the standard requirements that we use nowadays.

So, there is also a lot of need for mentoring because since we are very few that know about them, if someone wants to know about them there are no people to teach them. I have been devoting a lot of my effort in this mentoring, in this describing the diversity of these animals really from polar environments to the very tropical environments. And all these collaborations and all these mentoring has bring a lot of new collections.

And why are new collections important? Well, I want to show you this. There are some problems with these animals. Here, you have some images of how the animals look alive. Beautiful, I would say. And here is how I actually get them when people send them to me. So, there is a little bit of disparity between how the animal looks when they are alive and how they look when they are preserved. So, it's difficult. We need to actually study them, and we need new collections in order to really know what is the correlation between that thing and that beautiful anemone.

So, my main diversity studies come from Antarctica. I study Antarctic sea anemones. And the fauna that from that area - from Antarctica- is very special, but is also very unknown. I mean, it's not that easy to get there, obviously. And it's not only anemones that are unknown there, but many other marine invertebrates. So, there has been a lot of effort in solving this issue and trying to research the biodiversity of this area. And I have luckily part of it.

So, the good thing that if you work on Antarctic sea anemones, you might have to go there. And I actually have been lucky enough to be there. And in the case of marine invertebrates, usually what you do is you get in this huge research vessel with a lot of scientists all there for quite a long time: one month to three months, depending on the cruise. And you go there, and basically you have to send some nets and trawls down below the sea because they do leave starting out - I don't know - 400 meters and down. So, you cannot really dive that much there.

And you send all these trawls down there. They swipe the sea floor, and then they bring the animals, and then all the experts look and pick out their animals. And then you sort them out and you take them home to study them. So, my studies in Antarctic sea anemones have produced that we actually now know that there are around 122 species. And I have been lucky to describe several new species, one new family and two genera.

And, here, I'm showing you some images of these animals. These are pretty big animals, so it's actually amazing that since the 1800s nobody has done anything with them. You see them. It's not that they are tiny. So, in these last years I have been able to produce monographs in which I describe or re-describe a lot of this species; around 30 percent of its fauna. I have several or many species up there waiting for me to still describe them because they are new. And around 3,000 specimens are new in the collection for the museum from this research.

And this is how you would illustrate an anemone. You have images of the animal alive, of the animal preserved, of the internal anatomy of these stinging capsules, and then how it distributes. That is more or less the standards for studying these animals. Here, I'm showing you very fast an example of- I mean, it looks ugly because it's preserved. If it would be alive, you would have a nice picture here. And this is interesting - this one - because it actually loses the tentacles. When you disturb it, it loses the tentacle.

And it's this species from around 3,000 meters, and it's interesting because it's the second species of a genus. And this is only in Antarctica, and in the North Pole. And one thing we have noticed is that the species that are distributing in both sides of the world, they are very similar morphologically. They look alike. It's very difficult to distinguish them. And we don't know what is that, is like are they the same species. Or really that they are very similar? So I'm working a lot in that.

So, when you are studying an area, it's also very important to study the areas around them. And because I study Antarctica I'm, of course, very interested in the fauna around Antarctica. And for that I have been also studying the fauna from southern Patagonia; the really tip of the Americas. And I was lucky enough to go down there to the southernmost village in this world. And it was summer. It was snowing. And we spent a wonderful month there where we had to bring everything - I mean, boats, diving gear, anything, food included - to look for these animals. And we were diving in freezing waters; 4 degrees Celsius. And, well, we made some new discoveries, which is good. Because we were able to collect the specimens ourselves, we have nice pictures of the animal alive. And we can also do some molecular work and start studying the phylogeny of these species. Everything that we found was at least a new record. Of course, because nobody goes there. And I mean, you can see the diversity. They are all very different.

Another thing that I do is study the reproduction of these animals. So, once you know the species and once you have enough specimens of a species, you can actually study their biology. And in this case, I was studying how these Antarctic sea anemone reproduces. This one is a little bit special because it takes care of the young. And all those little bumps that you see around the column, those are the offspring or the babies. This anemone is characterized because it does take care of their babies, but it does it outside. So, we were able to do the first reproductive study of Antarctic sea anemone. And we actually were able to cover three seasons of the year because in winter you don't get to go to Antarctica. But three is enough. And we discover a new combination of sexual states for this anemone because there are female specimens. There are also male specimens, but there are also hermaphrodite specimens. We also discovered they reproduce seasonally, so not all the time, but each year. And it has a very slow development.

And here you have a picture that up to three different generations coincide on top of the mother. And we don't know if the fertilization is internal. And also because we discovered that they are hermaphrodite, now we don't know if actually these offspring is actually asexually reproduced or is sexually reproduced. And if it's asexually reproduced, it doesn't really make sense. Why are they going into all this trouble just to do something asexually? They could just divide like the others, but who knows, more to study.

So, I'm going to change a little bit, and now I'm going to talk about more extreme environments, or different extreme environments because I also study the diversity of sea anemones from chemosynthetic environments. And these ecosystems don't depend on the sunlight. They depend on energy that is derived from hydrogen sulfite. And basically in the middle of the deep sea, you find these oases of invertebrate fauna mostly. These environments were discovered recently in 1975. So, they are pretty new, and everything there is new. And all the scientists - we are very excited about them. So, I have been studying the anemones from there.

And what does it mean to study things there? Well, as I said, these are deep-sea environments, so we are talking about 1,000 to almost 7,000 meters down below. So, if you want to go there, you basically have to go in a submarine or you have to send remote operate vehicles - just robots that have cameras and arms and they collect for you. And these environments are in total darkness. It's pretty cold, around 1 degree centigrade. And the pressure there is very high; 600 atmospheres. So, 600 times the pressure that we have here.

And I had made a lot of discoveries. Again, every anemone that comes from there is new. I have discovered four new genera, eight species, but one other thing that we have discovered is that before all the anemones from there we thought that they belonged to a family of polar anemones. But after my studies, what we know is that they actually belong to a different family and that the anemones are in these environments - they come from two different lineages, from two different sources. So, some derived from shallow water anemones. Others derive from deep-sea anemones. Well, and this is like the perfect fit for me. A few years ago, they discovered these chemosynthetic environments in Antarctica. So, now I actually get to study Antarctic sea anemones that live in chemosynthetic environments. So, it's kind of perfect for me.

And those environments there are actually anemones are very abundant. If you see those images, all those are anemones. So, there are lots of them. So, I have been studying these anemones, too, and so far we know that the anemone fauna from these areas is related to the anemones from other chemiosynthetic areas.

So, now I'm going to change a little bit, and I'm going to talk about phylogeny. What is phylogeny? Relationships; who is related to who. And that's another thing that we do here. We generate evolutionary hypothesis. We try to discern evolution and how all these animals evolve, and how we got to what we see. So, anemones were classified in four groups, and I'm not going to kill you too much with this. Just keep an eye on the colors. Four groups; one of them having most of them. Subdivided in other groups, of course, which are, again,subdivided in other groups. And until 2008, there was no phylogenic studies of sea anemones. No molecular work had been done in sea anemones. So, we decided that we were going to do that. The result of that study was that we love trees. We always represent of this relationships into trees, and if the taxonomy would be a good fit with the actual phylogenetic relationships, the colors would match. And as you can see, colors are a mess. They are all mixed up, so that means that our classification is not natural at all. So, good. A lot of work to do.

So, I decided that I was going to study this thing; how are they related and try to make a more natural classification. So, that's what we did. And why do we need that? Okay, because we know that our classification - the one that we used - it was not really good. And why is that? Because actually anemones don't have any characters that characterize them. Sorry for the reiteration. They are mainly grouped because they lack characters. They lack skeleton and they are solitary. So, it was only very, very recently in 2012 that they actually discovered something that was unique to them. And it was a flap, or three flaps, in the stinging capsules that they sting you with that when these capsules open there are three flaps. And those are called apical flaps; those little things that you see with the arrow. These apical flaps characterize anemones. And so we decided to take all of these anemones and use molecular and DNA data to try to see what are the relationships among these animals.

And what we discovered is that instead of those four groups that I was showing you before, we actually have two big groups. The anemones are the ones in reddish. So, those are anemones, and they are divided into big groups. And that's a big contribution, if you are a systematist. Might not be. Anyways. So, another thing that I want to show you is that as many other things in science, discoveries come by chance or by surprise. We don't really expect them, and they just come out.

And I want you to look at that arrow because that actually correspond to what we thought that it was an anemone. It's this giant anemone. And molecular data says that is not an anemone. And it didn't matter how much we try, it didn't fit with anemones. So, who is that creature? Well, it's Relicanthus daphneae and it's a very large animal. It gets up to one meter of diameter. The tentacles are actually two meters. It lives in the deep sea in hydrothermal vents, and it's characterized by the lack of stuff. So, that's why it was put we think, with anemones. But our studies and all of these new classification that we did actually show us that this is a case of morphological convergence. I mean, it's easy to understand why these non-anemone was placed with those anemones because both of them lack stuff. But it's different in the case of Relicanthus. The thing is that it never had those things. But in the case of these ones that are actually very little, they lost all those characters. So, that's what we call morphological convergence.

What does it mean to discover a new order? Well, it's like discovering a whale for the first time, or discovering a monkey for the first time, or a mouse. If nobody had ever seen a whale ever, that's the similarity of the discovery that we did. But, of course, this is not a whale. Anyways, so we were really, really looking for some kind of morphological feature that would tell us why this is different, why it's not an anemone. Because that's what molecular data is saying. And we look and we look and we look in the structure of the stinging capsules, and what did we find? Well, we found that it has apical flaps; those little flaps that I told you. So, morphology's saying that it's an anemone. Molecular data is saying that it's not an anemone. So, we are still very confused about it. And what we are trying to do, we are actually sequencing the whole genome of this animal. And, hopefully, I will report to you soon what this thing is.

And with this, I just want to thank a lot of people, a lot of collaborators that have helped, the people that actually let me choose the beautiful images here, the funding sources. And, of course, all of you, thank you for being here listening to me.

[applause]

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