Briefing Chat: Orcas smashed a sunfish to bits — researchers aren't sure why

0:00If you're looking for something predictable and low friction over the long term, public markets may be a suitable option. But the moment you want different investment characteristics, it may be time to consider the private markets. See how your wealth can work smarter at creativeplanning.com slash access.

0:21Hi, listeners. Benjamin here. Welcome to the Friday edition of the podcast, where we talk about some of the stories we've read about in the Nature Briefing, which is, of course, Nature's daily email roundup of the latest science news. And joining me this time is Nick Petrichow. Nick, how are you doing? I'm doing well, Ben. How's it going for you? It's going A-OK, thank you very much. A couple of stories today. Why don't I go first? And there's kind of a through line, Nick, into the story that I covered on the Wednesday show. We're heading back to the Amazon for some newly discovered things, things that are new to science.

0:54But in this case, it's not archaeological remains. It's insects. And this is a story I read about in Nature based on a presentation at the Brazilian Society for the Advancement of Sciences annual meeting. So this is still preliminary data, but some of the numbers involved are quite something. I imagine so. I mean, many people will be aware of the fact that many insects are not known to science and there's a lot of them and they're all quite small. So it's hard to get sort of an assessment of them. But I'm guessing that they've tried to do that in the Amazon. Is that what you're hinting at? that's absolutely right and yes you're right across the board they generally speaking very very small although we'll get to some that are pretty big in a bit and well the amazon the lush rainforest has a huge amount of biodiversity as we know most of it is unknown it has to be said but now hundreds of scientists in brazil are collaborating on this epic project to count every species of insect in one expanse from the ground to the canopy and i think this is where this maybe differs from other examples of projects because trees in the absence can be you know pretty big right and they're looking at different layers as i say from the ground to the top yeah and the ecosystem can vary quite a lot between the canopy to the ground as well especially for insects for whom the ecosystem can be like just a little bit of a tree yeah and what they've done in this instance they've deployed three arrays of traps okay now each array consists of five mesh traps in a vertical stack if you can imagine that so one's at the floor and one is about 30 meters so about a 10 story building height above it and there's three more of these in between and when an insect flies into one of these traps it's funneled into a collecting bottle and they then are collected in ethanol, preserving their DNA for analysis.

2:48And that's key here. Scientists can't go and sort of count these one by one. They're collecting a large amount of these insects and then doing what's called DNA barcoding, which allows them to look at short fragments of DNA to work out whether a species is new to science or whether it's already been established, this sort of thing. You said that the goal is to catalogue every insect species, but that sounds like it would only capture the flying ones what are they doing about other insects yeah that's a great point and one that i wondered about too and to catch species that would otherwise have been missed by this sort of trap the team organized a collecting blitz of sorts last november that used around 50 extra collecting methods and in one example they used rotting meat to attract insects that feed on carrion, that sort of thing.

3:39And they use light traps to sample nocturnal insects that may have been missed otherwise. So they've done their best to try and run across the gamut. And as I understand, they've been looking in a particular area of the central Amazon in northern Brazil, and they've been collecting insects for over a year, and the results are 5.5 million specimens, of which 600 ,000 will ultimately have their DNA sequence. Then a huge network of taxonomists will combine this genetic data with looking at the insect's physical traits to identify, like, what are these species? And of course, if it's a new species to science, they get to describe it and name it.

4:21I mean, it sounds like a heroic effort and, you know, an important one to know what insects are there. But do they think it could have other impacts? Could it tell us a little bit more about the overall ecosystem and how it works? Yeah, I think that's the central thrust of this. Now, I've covered the naming of species and why this is important in the past. And we know that insects around the world are under threat. Climate change, insecticide use, habitat loss, certainly in the Amazon, that's an issue. And it's really hard to conserve a species if you don't know it's there. I remember talking to someone who discovered a new lizard in Ecuador a few years back.

4:58and they said that by giving it a name by giving it a hook that you could hang a label on that can then direct things like funds for conservation or you know getting media attention that sort of thing so i think in that instance it's kind of important but it's going to be a heck of a job they found loads of stuff already preliminary data suggests that the number of species could surpass 40 000 many of which will likely be new and this number is apparently less than one percent of the widely accepted estimate of all the insects living worldwide and people put that number about six million but this 40 000 is for a single location in the amazon so if you much like our story about the archaeology expand that out the numbers i mean they boggle the mind a little bit it has to be said yeah yeah certainly and you know i imagine that the amazon is a vast area has a lot of different ecosystems and different places that insects could live so yeah it could be as you say a mind-boggling number and i'm sure it'll be a lot of work for them to carry forward to the future but i am curious about some of the examples that they might have found can you tell me about some of the cool things oh yes someone who's not the biggest fan of insects who respects them from a distance this one it gave me pause for thought i have to say but the article quotes one of the leaders of the project someone called dalton amarin who is an entomologist and he and his team are sequencing over 300 000 specimens which they're expecting to have done at the end of august and he says that most of the things they've seen so far are flies and mosquitoes which you might imagine some are little moths and butterflies and tiny wasps and bees cockroaches and this is where it kicks in some of these vary from a half a millimeter long to giant predatory crickets that measure more than 10 centimeters long that's a pretty big cricket that's a big cricket yeah and apparently the most abundant insects collected belong to a family of flies called cecedomyidae which are commonly known as gall midges now these are only maybe a couple of millimeters long and over the past 250 years scientists have described nearly 7 000 different species of this worldwide and in this work they've already found 10 000 species from a single trap wow yeah and there's this wonderful quote from amarin here in which he says people tend to picture the rainforest as a minecraft cube green and uniform but in reality it's far more complex than that as we begin to understand insect guilds how they live and the heights of the forest they inhabit the forest becomes an incredibly interesting and rich environment when a patch of forest is cut down thousands of species are affected i think this really does show like you know how much we don't know about the amazon but hopefully we'll learn a little bit more about it from this gargantuan effort and speaking of like new things or learning new things i wanted to talk to you about a never before seen behavior of orcas where they seem to um well to put it lightly explode some fish right i mean this is a sentence that we need to explore orcas sometimes folks still call them killer whales i guess but very intelligent creatures and this is as you say what a new behavior unknown to science yes this is something that was quite shocking to the researcher who observed it as well but we'll get into that in a second so yeah as you say orcas are the largest member of the delphinidae family so dolphins and the like and they are predators and they hunt together quite often so there's been a lot of different behaviors that have been noted by orcas where they'll sort of like ram whale sharks and that sort of thing to try and get valuable meat but in this case what this was was this was a single orca holding a sunfish so this is a great big funny looking fish that looks a little bit like a sun that's the name and they're holding it in their mouth while another orca not takes a step back takes a swim back i guess and then rams at it at high speed exploding the sunfish everywhere and so this is something that I was watching in a nature video made by Maren Hunsberger, one of our colleagues who's appeared on the podcast, and I was reading about in the Guardian.

9:12And I also read the paper in Frontiers of Ethology, where they sort of detailed their observations and what it might mean. Huh. And I'm not sure the right word to describe what happens to this sunfish then. You can't say it was vaporized because, of course, it's underwater. So I guess chum, what's that that's that kind of mashed up fish that's used as bait do they turn it into chum nick i mean it's funny that you should say that because one of the things that the researchers believe may be happening here and there's a few ideas because they're not entirely sure what they're doing is that they could be processing the meat so rather than having a great big sunfish that might be difficult for say the juveniles to eat have smaller jaws what they might be doing is exploding it or you know chumming it in order to make the parts smaller for the other juveniles to eat but i will say that one of the most fun parts of this story is that one of the researchers behind this work was actually in the water with the orcas when this happened and was recording with a gopro and there is a video and i'll link to it in the video you can hear them going oh my god oh my god and something else that i wouldn't repeat on the podcast as this happened so it was quite a shocking event for them goodness me right and was the sunfish kind of flapping about was it still aware of what was going on before it was ended that's a very good point the sunfish was already dead which is one of the ideas of why the orcs are doing this as we said maybe to process the food and they did observe that the juveniles did then eat the little bits of the sunfish so it's already dead so this isn't a hunting behavior this is not how they're actually killing the sun fish in the first place but they have some other ideas of why they might be doing this as well so for example the sunfish have this layer underneath their skin it's like a fatty layer called the capsule which is very rich in a very unique microbiome and all the rest of it and so one of the other ideas could be that the yorkers are trying to get access to that they're trying to access this unique microbiome and that microbiome could be useful for the orcas it could help them be healthy or it could intermingle with their own microbiome and you know change things in a way that's advantageous to them the other idea though is that maybe the orcas are just doing it for fun yeah that was my question is could they just be dirtbags who just like exploding fish well yes orcas are known to play with their food so for example in the 1980s it was observed that orcas would wear dead salmon as hats essentially okay like a group of orcas would just do this for fun and they are like playful creatures so it could be that they're just doing it for fun but ultimately the researchers think this shows a great deal of cooperation and coordination as well like it's not easy to hold the sunfish in such a way and then ram it with a another orca in order to do this and this combined with other behaviors that have been observed as i mentioned they are known to work together to like ram whale sharks and things to get access to food and they do a bunch of other like cooperative behaviors as well so this is just showing the degree to which they have this sort of intelligent and collaborative and cooperative behavior right and you say this is the first time this has been seen and fortuitously captured on film so i guess a question is was this just a one off one orca had hold of it and another one rammed it or is this a pattern of behavior i guess you need more than one example for it to be a pattern well it's a fair point and this may be a two off because the researchers did video it again so after seeing this first behavior so they have seen it at least twice in the same sort of area whether other orcas in different parts of the world do it they don't know but at least in this area which was just off the coast of california orcas have been seen to do it at least twice in order to get other footage to maybe see if they do it or just to understand what orcas are doing a little bit more one of the things they discuss in their paper is the growth of tourism and how many more people have access to underwater drones that could potentially capture footage so that is something that they could potentially look to and maybe do some sort of citizen science sort of thing however they do caution that that would have to be approached carefully because tourism can also be very disruptive for marine ecosystems and for the orcas and that sort of thing.

13:41So maybe there's some way that scientists and regular citizens who happen to have fancy cameras could work together in order to see this a bit more. But yeah, whether this is a behaviour, I'm not sure, but they've seen it at least twice. Well, I'm not sure we can top that. So let's call it time for the podcast this week. Listeners, we'll put links to both of those stories so you can read more about them and watch the orcas in their horrific games over in the show notes. And we'll also put a link where you can sign up to the Nature Briefing to get even more stories like them delivered directly to your inbox.

14:17And as always, if you want to get in touch with us, if you want to tell us how you feel about the orcas smashing a sunfish, then you can. You can reach out to us on social media. We're at Nature Podcast. Or you can send us a good old-fashioned email. We're on podcast at nature.com. I'm Nick Petra-Ciao. and I'm Benjamin Thompson. See you next time.