We speak with George Matsumoto about the fascinating world of deep sea jellies.
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George Matsumoto
Marine biologist & Senior Education and Research
specialist based in MBARI
I’m joined by George Matsumoto - a marine biologist and Senior Education and Research specialist based in Mbari. his research focuses on deep sea communities with a particular focus on invertebrates and gelatinous things; their ecology, behaviour and evolution.
thanks for coming on to have a chat George!
Thank you very much for the invitation, it's a pleasure to be here.
we came onto this topic because on the last episode we were really enjoying some of the new footage from the dive streams. In particular, the recent observations from the EV Nautilus of the orange jellyfish at about 1400 meters. I think they they narrowed it down to the bathykorus genus, but this one was unusual being sort of a red-brown colour. Did you manage to catch that in the news?
I did and in fact, I was watching that live dive when it happened. Which is unusual because we've been blessed lately with a number of live dives that are happening simultaneously. So, it's been challenging to watch all of them.
we used to fight over a little bit of deep sea footage but now we can flip channels!
It is crazy to see the difference because you know, literally five years ago you would be hard-pressed to find some live feeds and now it seems like you could have live feeds coming from two or three different remotely operated vehicles.
And it's doing amazing work at demystifying the deep sea because it's well-illuminated and it's beautiful and it's not ‘secrets’ and it's not ‘monsters’. we're all just going on this amazing dive together and seeing some incredible things. I think it's doing so much for deep sea’s image, demystifying that and removing the horror, the ‘alien’ aspects because it's just beautiful.
Absolutely, that's right because the animals down there are not horrific and they're not scary and they're not monsters. I'm not sure if we're really demystifying things because with so many vehicles sending back so many images, we keep finding new things!
The new bathykorus jellyfish seen on a recent dive with EV Nautilus
that is true, like this orange jelly that we mentioned. can you tell us a little bit about this group of jellies?
Yes, so this is a really interesting jelly. It's a hydrazoan jelly, and hydrozoa is one of the classes in the cnidarians (or the jellies). The bathykorus was first described in 2010, so even the genus is not really an old genus. It's a deep sea species that was described originally from the Arctic Ocean, actually by a colleague of mine - Kevin Raskoff. He described this bathykorus as it comes from the Greek name ‘bathy’ meaning ‘deep’ and ‘korus’ meaning ‘helmet’. So, it's the Deep Helmet and it refers to the shape of the bell which reminded him of Darth Vader.
The ‘Darth Vader Jellyfish’, first described by Kevin Raskoff in 2010.
Yes, oh that's a great reference!
So this actually got a lot of press when it was described because of course he called it the Darth Vader jellyfish. When you look at the original description, it's an opaque white jelly with four tentacles. In between each tentacle are three what we call ‘stomach pouches’. So this is an interesting animal because the original species has 12 stomach pouches and this orange one that we just saw recently, 1) it's orange, 2) it only has three tentacles, instead of four. And of course, because it only has three tentacles: now it only has nine stomach pouches, instead of twelve. So the question of course is: is this just a completely new species in that genus or did something strange happen so that it has three tentacles instead of four?
Or it could just be an unusual individual…
Absolutely! The animal that we did see was not a full adult. Although, it was not a juvenile either and they couldn't really see well-developed gonads which sometimes you see. But even on some adult jellies sometimes you don't see the gonads anyway if they're not reproductive.
So learning about deep sea animals is difficult, and learning about deep sea jellies is even more difficult because you cannot collect them usually with nets.
Or what you get, you're not particularly happy with. I've seen it just as wallpaper paste being poured out of a cod-end.
That's right. One of the advantages of studying fish is that you can actually get specimens with nets. They're not in the best shape sometimes, but you get specimens.
And the fish come back so badly damaged, what hope does a transparent gelatinous animal have? Essentially, it's just been pushed through a sieve.
That's right. So they don't look very good when they get up to the surface in a net. But that's kind of the exciting part for me, because the deep sea is full of interesting animals that we really haven't seen the light of day yet because you can't collect them in a net. So every dive to the deep is kind of a really neat safari into the unknown, in terms of gelatinous animals.
Does it cause issues when it comes to to species descriptions? There's a debate that's been raging forever and it's only getting more heated now that our visuals are getting so much better in providing a holotype.
Well that's a really good question. I think that when you describe a specimen, you not only have to have the morphology right, what it looks like. But these days you also need some DNA. You need to be able to sequence part of the genome, if not the whole genome, so you could put it into its proper taxonomic place molecularly. And then, I think it's also important to have a holotype and some paratypes (some extra specimens) so that scientists of the future will have something to look at and compare it to. And that is a current issue right now, because when we described new species sometimes there's holotypes or paratypes in the museums, and more often there are not, they're just illustrations and sketches and descriptions. And you're sort of left wondering… has this been described before or is this something new?
Yeah and we've got no way of knowing. Just in the last five years, the amount that genetics has come on… we've got no way of knowing what will be possible with the material we're archiving now in museum collections. I recently started working in a museum and every time I put a tissue sample away I'm thinking: it might be hundreds of years and somebody might do something really cool with this. I almost feel like I'm passing it to them through time.
I think that's a great way to look at it and that's and that's absolutely right. We may not be able to do any of our own work with these specimens, but somebody down the line… well, I really do believe that. So I think it's important to have a holotype and some paratypes and and I think having both is important. For instance, I've gone to the Smithsonian to look at holotypes and I found out that somebody was there before for me and cut the animals up to look at their gut contents. And now the holotype isn't really a holotype anymore, because it doesn't look the same.
Yeah it's so tricky because quite often there's destructive techniques and they pull these needs in different directions.
Right, so there's a reason to have multiple samples in a museum so that people could look at them and hopefully leave at least one of them intact, so that somebody else can look at it in the future. But having the DNA and having a molecular sequence, I think, is is really important. I think it is good if we do the sequences ourselves, because storing a tissue specimen in a freezer can be difficult. Because that means that 1) you have to hope that the power never goes out wherever you've got it stored and 2) the specimen doesn't get lost somehow. And for some of these jellies, you may be talking about a tentacle, and that's easy to lose.
yeah the vial gets damaged or the the label rubs off, or just funding becomes inconsistent. you can only lose it once, if that makes sense. it's got to persist for hundreds of years, whereas if it's data, we can back it up.
Yeah, I think a great study would be to go back to some of the original jellies that were described, the type and location and look for some specimens. Because we don't have specimens or DNA from these original descriptions, but if we could find some jellies in the same areas, we could tell ourselves that this is probably the animal that was described in that type specimen. Then we could say: here's the paratype or here's the holotype or here's the DNA from this species that was described 100 years ago.
we're so overwhelmed, there's so much new material and we find so much new stuff on every single Expedition that there's just a lot to do. so It's tricky to go back and do the due diligence.
We need more students who are trained in this and are willing to do this type of work. I think you've hit upon a great issue with our field. Because even at MBARI for instance, we may have described over 200 species in the short time we've been around (because we've only been around for 35 years), but we probably have another 100 species that we know are un-described but we haven't had time to work on them yet. And a great example of that is that there's actually an un-described species on display as part of the ‘Into the Deep’ Exhibition at the Monterey Bay Aquarium.
I've told students a few times: the best place to find a new species is in a museum collection. because there's such a bottleneck, it takes maybe one expedition to capture something, but it could take two years to get it properly described.
Oh, two years I think, is really fast.
I'm glad you said that because I am slow. I like to think I'm thorough, but I'm not quick.
It's got harder too, you know. When I first started in this field, I did have some early species descriptions and they were just morphological, because it was before DNA. And these morphological descriptions took maybe a year or two years, but now you have to do the sequences. And it's not enough just to sequence the species you're describing, you really should be sequencing all the other related species, to make sure it's not one of those. And that's what takes the time because now you have to go get specimens.
Yeah that's true. But as we as we're building up these databases, there is this lovely collaboration. we do a bit of work and then we throw it out to everyone and say: ‘hey, this might be useful for you,’ and ‘this might give context to what you're looking at’.
That's right. I think that's a great part of the scientific field is that most people don't sit and hoard the data thinking: ‘one day somewhere down the line I'm going to use a sequence’. Scientists are really good about sharing that type of data because everybody realises that you could be holding up some work somewhere if you're not sharing that sequence.
Yeah and we've all got more than we we know what to do with, so withholding always backfires because there's always more coming in.
That's right. And there's not enough people working in the deep sea yet to the point where we're going to start running out of material.
so to come back to that new Jelly, is there a reason for these multiple stomach pouches? or is it about the radial symmetry? is the body just these repeating units and you can make a circle from as many as you want?
I think it's that latter statement, I think it's just a issue of symmetry. It's hard to know why they have multiple stomach pouches. Theoretically, it could give them an advantage if something came and and took a little nibble out of them. If they lost one or two stomach pouches, they're still okay because they got a few others. If you only have one stomach and you lose it, that could be problematic.
But there's also a lot of plasticity, a lot of variability, in some of these jellies that we still don't really understand and we're still learning about. It's interesting to me because some things are considered diagnostic features. A good example would be: the larger jellies which have things we call ‘oral arms’. The big arms in the middle of the jelly that work not only as pre-catching devices but are also essentially stomachs. They’re mouth arms we call them, because they not only catch food, they also digest food, and for a lot of animals a lot of these jellies, the number of arms is considered diagnostic. i.e do they have four arms or five arms? But there's a fairly significant jelly that I was a part of a team that described it that his nickname ‘Big Red’ or Tiburonia granrojo, a really big red jelly. No tentacles, mouth arms and it could have anywhere from three to seven mouth arms.
Tiburonia granrojo (Image courtesy of MBARI)
are they the really huge ones?
They're the really big ones, yeah. They get up to a metre in diameter and you could probably pick up in a net. But it's interesting to me that it has a varied number of oral arms. So every time I see one, I'm sitting there counting arms, just because I'm curious. I don't know what the advantages are, or what it is about their genome that says: I'm going to have three arms, or I'm going to have six arms. Because when you have seven or five, it's not necessarily symmetrical anymore. Whereas four, that makes sense, you have nice repeating units. Luckily, so far, it's the only meter wide huge red jelly that's really thick that we're found. There's every chance there'll be another and another after that. I mean, who knows maybe the three tentacles is one species, four is another, five is another. I don't think that's true, but we don't really know because they're too big to collect. We've never collected an adult, the biggest one we've collected is about the size of a softball.
oh really?
It gets so big, that's a problem in itself. So we did finally get a holotype and that's the one that's in the museum up at the California Academy of Sciences.
can I ask about preservation, because I've certainly seen samples of jellies be put into preservative and then just immediately disappear. what are they preserved in?
A ctenophore or ‘comb jelly’ Hormiphora californensis. Image courtesy of MBARI
Yes, so ctenophores or the comb jellies are prime examples of that. They do not preserve well except for the benthic ones. The ones that live in the water column just dissolve. The best luck I've had with preserving them is in cooled glutaraldehyde. Almost matching their viscosity and temperature. And the problem with that, of course, is you really need to keep it cold. So now now you have an archival problem. If you give it to a museum and the museum doesn't really want glutaraldehyde on their shelves, eventually they’ll want it placed into ethanol and when you do the transfer it doesn't really work well.
something else we were chatting about a few months back: we were all stumped by the bluey-purpley-spiky-blob that was filmed in the Atlantic Ocean
Yeah I forget exactly where it was filmed but they saw it earlier this year in June. It was first spotted in 2016 maybe, off the Channel Islands off of Santa Barbara and fortunately that was an animal that the Nautilus was able to collect. When they collected it, they found a foot, a muscular foot and rhinophores. They were able to identify it as a nudibranch - a sea slug.
Blue spiky blob that has since been found to be a nudibranch.
I would not have guessed nudibranch!
Which is just amazing right?
I mean, they have some amazing forms, but no way! that looks sessile.
Oh it gave us a good run yeah. And we see things like that here at MBARI. I remember the first time we found an animal that is now called ‘the mystery mollusk’ swimming in the water column. A beautiful animal that is featured now on some of the NOAA literature. But when we first saw it, I remember sitting in the control room and for about 45 minutes, we were all arguing trying to figure out what phylum it was in.
you're right at the base of the tree!
The ‘mystery mollusk’ from MBARI
Yeah! Is it a tunicate? Is it a jelly? Is it a sea cucumber - because we couldn't tell. It was swimming like a jelly but it looked like it had organs. So, maybe it had extensions like a sea cucumber, and so we just kept going on and on and on. Even upon collection we couldn't really tell. We could rule out cnidarian, we could rule out jelly because it clearly had organs. But after that, we were sort of stuck. It did take sequencing to identify it as a snail. So that was over 20 years ago and just to show you how difficult it is, that has not been published yet. We're hoping it's going to come out in the next year.
It's such a new frontier still. there's so many exciting things going on that we can have the footage, we can have the specimen and still not be sure. and then like you say, sometimes the work takes so long because it is so fundamentally different that it's gonna wobble the whole tree.
Yes. It's not enough to just give a species description, you now have to make room in for it in the trees that already exist. And that's often the hardest bit of work because now you're nudging a lot of other people's work.
they're almost two separate problems. do you get a species out there so that we can talk about it and look for them. almost leave where it sits in the tree for for a much bigger debate. because they feel like two quite separate but very linked parts of the process. but it’s difficult.
Oh you're right and you know even lately the tree of life has been shaken a little bit with the comb jellies. We're looking for our our earliest animal ancestor and…
it's been a fight between them and the sponges for a while.
That's right and so the latest paper seems to put the ctenophores down low and the sponges a little further up. And that of course raises a lot of controversy as well.
yes I think it's quite healthy in the scientific Community that we regularly find out that everything that we believe is wrong. we're continually open-minded.
Extraordinary claims require extraordinary evidence but we we stay open-minded as we get older which I think a lot of people galvanise. I mean, that to me is the essence of science. For me, part of the fun of science is there are no absolutes and you do have to be remain open to what other people are talking about.
yeah I think we just become more right. I think ‘right’ is a perfect state which we’ll never actually reach, but I think we just head in a direction of becoming more and more right.
I don't know if we'll ever find those absolutes. Yes I think they're there under the hood, but it's a process.
Which is often something that's thrown back at us. It's like: oh well you used to think this and now you think this. And it's like, isn't that a good thing? Wouldn't you worry more if we just dug our heels in and said ‘no I'm not changing my mind’?
That's right, absolutely.
are there any real incorrect facts that just propagate and you'd really like to go on the record and just say: that is not true, this is the case?
That's a good question. I guess the example that pops to mind first, is that for the animals that I like to study, the ctenophore or the comb jellies, most of the illustrations in textbooks have them upside down with the mouth on the bottom and the tentacles up in the air. I'm not quite sure where that started but of course, you know textbooks, every revision they tend to repeat it over and over again. So that would be fun to fix one of these days. But I think the biggest misconception is the one that you alluded to earlier in our conversation and that's the idea that the deep sea is full of dark scary monsters. Because I don't think it is. I think there are some beautiful amazing animals down there and even the ones that when people see photos of them think that they're really scary, they're not really scary because they're not really that big. It's like the fang tooth or the viper fish, with their big teeth. They need big teeth because food's hard to find and when you find food you want to make sure you hold on to it.
oh that was brilliant. thanks so much for having a chat with us George. was there any final thoughts you wanted to add?
Well I think the only final thought I'd like to say is that if there's any students out there interested in studying the ocean, to do it! We need more people interested in the ocean, it's the largest habitat on Earth, provides 98% of available living space, covers 70% of the Earth's surface and we still don't know very much about it! We don't understand it very well so it would be great to get more people helping us learn about the ocean.
that's brilliant. thank you so much for your time George it was a really enjoyable chat.
Oh, my pleasure!