IRA FLATOW: This is Science Friday. I’m Ira Flatow. Later in the hour, we’ll talk about plastic batteries, why mosquitoes are so annoying, and the weird and wonderful history of sex, yes. But first, some exciting news in science this week. Scientists recently crowned an underwater meadow of seagrass as the world’s largest plant, beating out a colony of Aspen trees that once held the title.

Joining me now to talk about this discovery and other science stories of the week is Sophie Bushwick, technology editor at Scientific American based in New York. Welcome back, Sophie.

SOPHIE BUSHWICK: Thank you.

IRA FLATOW: Nice to have you. OK, so science is just discovered the largest known plant on Earth. Tell us about that.

SOPHIE BUSHWICK: So this is a plant that covers an area about 77 square miles. That’s a plant the size of Cincinnati. It’s a particular kind of seagrass called Poseidon’s ribbon weed, and there’s lots of meadows of this off the coast of australia. So researchers were studying the genetics of it and they took samples from all these different Meadows, and what they found was many of these samples were genetically identical, which suggests they are all clones of the same seagrass, and that it has been growing in this area for about 4,500 years.

IRA FLATOW: Wow, wow. It’s lasted millennia. How has it lasted this long with changing climate, other woes?

SOPHIE BUSHWICK: Well, they think that one of the keys to its survival might be the fact that it has two sets of chromosomes, which is something called polyploidy. Now, this is not good in animals, but in plants, it apparently has lent this particular plant some resilience to changes in climate. But it has also made it impossible for it to reproduce sexually, so that’s the reason it’s cloning itself and making all these genetically identical versions is because that’s the only way it can reproduce.

IRA FLATOW: I’m reminded of the humongous fungus that used to hold the record for the largest living organism, I think.

SOPHIE BUSHWICK: Yes, I mean, and that’s also kind of contentious. What counts as the largest organism? So you could argue that the Aspen Grove you mentioned, is still the largest individual plant because its root system is all connected. But this would be the largest plant overall.

And then there’s the question of are we talking about the area of surface it covers, because this covers a much greater footprint and area than the aspens do, but does it weigh as much? So there’s all these different criteria when it comes to it to the official largest plant, but this one definitely covers a super, super impressive area of the ocean.

IRA FLATOW: All right, let’s pivot to the animal kingdom right now. There’s been some new research on what countries are most responsible for the rise in animal extinctions. What did this study look at?

SOPHIE BUSHWICK: So this study was looking at how consumption and global trade creates this demand for resources and how often, the place where these resources are consumed is inadvertently affecting areas thousands of miles away. So for an example, you can look at the Western lowland gorilla, which is this very endangered species. Its population is expected to plummet by about 80% over the next 65 years and it lives in Cameroon and neighboring countries.

But the reason it’s endangered is because raw materials being extracted from its habitat, and those raw materials aren’t being consumed in Cameroon. They’re being shipped away to other countries, they’re being shipped to China, where they’re made into products that are then sold in the US. So in that way, the US is driving this extinction, even though consumers in the US might not be aware of it at all.

So what these researchers wanted to do is say, which countries are driving extinction in other areas? Which countries are suffering from biodiversity losses due to consumption patterns in other countries, and then which countries are in a situation where it’s their own domestic consumption that’s driving domestic loss of biodiversity? And what they found is there’s a group of 76 countries they call importers, which are importing products and thus driving the decline of endangered species abroad, and the US is a big one in this category.

Other members include Japan and France and the UK, and then there’s a smaller group of countries of only about 16 that researchers classify as exporters. So they’re exporting products, which is causing biodiversity loss and endangering species there, and that’s only about 16 countries. And then there’s 96 countries where it’s domestic consumption. That’s the problem that’s driving extinction risk inside those countries.

IRA FLATOW: Let’s turn to another ancient organism. The animal called a trilobite. Some interesting news about trilobite fossils here?

SOPHIE BUSHWICK: Yes, some trilobite naughty bits have been exposed by this 508 million year old fossil. So this is the first known male appendage sex organ from trilobites, and it’s not a penis. It’s something called a clasper, which is a part that certain marine species use during mating. The male will have this and it’ll use it to hold the female nearby so it can release sperm and be more confident that they will fertilize the female’s eggs.

But it’s really hard to find these parts, because any soft parts, it’s hard for them to survive. And trilobite fossils, they’re some of the earliest hard bodied animals, and there’s a ton of them in the fossil record because of those hard bodies, but their soft bits aren’t preserved. Researchers have to extrapolate that they exist based on maybe spots in the shell where they think a leg attached.

But this particular fossil was fossilized on its side, and so a lot of its appendages were preserved, including these claspers.

IRA FLATOW: Wow. That is an interesting sex act that they do there.

SOPHIE BUSHWICK: Yeah, a lot of modern animals also do it. Sharks, shrimp, horseshoe crabs, many of these species have claspers. But the other thing is that this is a particular trilobite species. There’s about 20,000 trilobite species that we know of, so it’s possible that some of them didn’t have this organ.

IRA FLATOW: Interesting. Interesting. And we’ll be talking more about the secrets of animal sex lives a little bit later in the program. Not trilobites, but there’s even more weird animal news this week such as why mice are afraid of bananas. I had no idea, Sophie.

SOPHIE BUSHWICK: Neither did I.

[LAUGHTER]

Yeah, so researchers were looking at some male mice and how they behaved around pregnant and lactating female mice. And they found out that these mice were getting incredibly stressed out, and they traced it to one particular chemical compound called N-pentyl acetate that was in the urine of these females, and it just so happens that compound makes bananas smell like bananas. So the researchers had already tested how the males behaved when they were exposed to this urine.

So now what they did was they bought some banana oil and put the males in a cage with it. And sure enough, the male stress response spiked. They started releasing this chemical that indicates that they were upset and scared, and it was all because of that banana smell.

IRA FLATOW: And so what does this discovery tell us about animal communication?

SOPHIE BUSHWICK: Well, one thing that male mice tend to do is eat mouse babies, so this is something that they might do if there’s a female with babies, she might be less likely to mate with them and get pregnant, so they will eat or otherwise kill these babies and then mate with the female. So the females have evolved this defense mechanism, which is that when they’re pregnant or they’re lactating, they will release this chemical and that freaks out the males in an effort to drive them away.

IRA FLATOW: Oh, can we use this new knowledge? I mean, I’m thinking of the pesky mice that live in my basement. Maybe some sort of mouse repellent with this idea?

SOPHIE BUSHWICK: Yeah, my first instinct was like, I got to go buy bananas and put them all around my apartment. But the problem is it’s not clear whether female mice are quite as scared of it. So you might end up providing some fruit salad for female mice and actually attracting them when you’re trying to drive away the male mice. So I don’t think that this is ready for prime time yet, but it is an intriguing direction that maybe researchers could keep exploring.

IRA FLATOW: Cool. Cool. Next up is a tech story. Scientists built a tiny robotic crab, but this is a really tiny crab, right?

SOPHIE BUSHWICK: It’s about the size of a flea. And it’s really cool because the way it moves, it’s made of this material called a shape memory alloy. Basically, it’ll change its configuration from its original shape to a different one based on how hot it is, and the researchers used a laser to heat different parts of the body from a distance. And as it gets hotter and then colder, its conformation changes and that makes it move. It can skitter sideways in a motion that’s very similar to the way a crab sidles back and forth, and in fact, that’s the reason this team chose to develop it in the crab shape because its motion reminded them of it.

But I mean, it can also twist up its legs, it can crawl, it can even jump based on how they hit it with this laser.

IRA FLATOW: Wow. So what would be good use for something this tiny?

SOPHIE BUSHWICK: So you can imagine a tiny robot like this maneuvering in a very confined, small space. Possibly, it could be used someday in the future for some sort of surgical procedures. Maybe it could be used to assemble very tiny delicate machinery as well.

IRA FLATOW: I’m wondering, OK, let’s say you use this in the body I’m thinking of the old movie Fantastic Voyage. You have to Google that.

[LAUGHTER]

So what happens if it’s in your body? How do you get rid of it? They would have to think about that, I would imagine.

SOPHIE BUSHWICK: Yeah, I think they would definitely have to consider that this is more of like a prototype proof of concept device. I definitely would not want one of these in my body at this stage in its development, but I think the idea is eventually it would be manipulated into the body and then manipulated back out.

IRA FLATOW: Are researchers looking for other critters to base robots off of?

SOPHIE BUSHWICK: Oh, all the time. Even just this particular research team, they’ve also developed little robots that look like other insects like beetles and inch worms.

IRA FLATOW: This does seem like a fruitful technology to move forward with.

SOPHIE BUSHWICK: Yeah, another really cool thing about it it’s manufactured in two dimensions, so it’s cut out as a flat shape, but it’s made of this sort of springy material that pulls on the 2D shape and Springs it into a 3D one after it’s been cut out.

IRA FLATOW: OK, we’ve got time for one more story and this one takes us to space where scientists have a new way to study outer space from home, right? Tell us about that.

SOPHIE BUSHWICK: Yes, this is really cool, because it repurposes existing data and information, so it is basically an algorithm that lets researchers hunt for asteroids without having to look through a telescope or even launch a specific new asteroid telescope. All they have to do is apply this algorithm to existing images and data that have already been gathered. And it picks out spots of light that might be asteroids and then, if those are confirmed, it can start calculating the orbit of those asteroids and maybe say, hey, is this thing going to be coming close to Earth? Is this a potential threat?

IRA FLATOW: Have they discovered any asteroids out there yet?

SOPHIE BUSHWICK: Yes, they looked at a setup data from one lab for a limited time period of just several years, and they found more than 100 asteroids in that data.

IRA FLATOW: Any of them a threat to our planet?

SOPHIE BUSHWICK: As far as I know, you don’t need to keep an eye on the sky just yet. They don’t seem to be imminent threats to us, but this is just a really intriguing option for looking for asteroids. So NASA says that they’ve already discovered about 30,000 near-earth asteroids. So 100 isn’t a super large amount compared to that, but that’s just what they got from one set of data.

So it’s really exciting to think of what they’ll find when they start applying this more widely.

IRA FLATOW: I’m sure asteroid nerds are jumping up and down.

[LAUGHTER]

Because it’s low maintenance, right? You don’t have to spend a lot of money and build telescopes and do things like that.

SOPHIE BUSHWICK: Exactly. It’s high reward for low cost.

IRA FLATOW: Well, thank you very much, Sophie. Always good to have you back.

SOPHIE BUSHWICK: Thank you.

IRA FLATOW: Sophie Bushwick, technology editor at Scientific American based in New York.

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