My very first blog post was September 2008. A lot has changed since then—I started and completed a PhD program at the University of Hawaii (where I met my partner and now baby-daddy), did a post-doc, wrote one book (that you should really read—just ask Amazon or Smithsonian) and edited another (on science blogging!), and started a new full-time editing job with the YouTube science channel SciShow. And over those ten years, I have written more than 800 blog posts, my blog has gone from being called Observations of a Nerd to Science Sushi, and it’s moved from Blogspot to Science Blogs to Scientific American to Discover—and now, it’s making one last move.

I started blogging because I wanted to share my passion for science with the world. And my posts have done that—they’ve also opened up new avenues for sharing my passions. I owe a lot to this online platform I started on a decade ago. If I hadn’t started blogging, I wouldn’t have the writing career I have now. Even my partner and I bonded over our mutual love of writing online (and I still think his blog is so much cooler than mine), so it’s impossible for me to imagine what my life would have been like had my friend Allie never suggested I try my hand at it. But now, I get to nerd out over awesome science every day in the scripts I work on for SciShow and through my freelance writing for places like National Geographic. So the time has come to close the book… or, the laptop, I guess.

It’s been a decade, and it’s time to move on. Since I’ll no longer be blogging regularly, Science Sushi is moving again—this time, to a permanent home, ScienceSushi.com. The archives will still be hosted here at Discover, as well as at my blog’s new home, but I won’t be updating the blog with any regularity. If I feel particularly moved to comment on the world of science, I reserve the right to post a new post every now and then at the new site, but this is my last post here at Discover.

Thank you to all of my regular readers—you have made the past decade truly wonderful. And to those of you who might just now be stumbling across this blog, don’t worry: I’m not going away. If you subscribe to SciShow and SciShow Psych, you’ll hear my words and the words I edit frequently, and you can keep up to date with any other freelance writing I do by following my Facebook page, Twitter, or periodically checking out my website. I’ll be somewhere on the interwebs, just not here—and I hope to see you around.

— Christie

The year was 1983. Star Wars: Return of the Jedi had just hit theaters, The Police’s “Every Breath You Take” topped the charts, and Amos Barkai was a new graduate student at the University of Cape Town in South Africa. He’d recently gotten his bachelor’s from Tel Aviv University, and was excited to start his graduate work under George Branch. Little did he know he was about to discover an ecological phenomenon that would earn him a prestigious paper in Science.

Branch had been investigating the effects of bird guano runoff from islands on life in the intertidal—the zone between high tide and low tide—and he was interested in seeing whether the effects extended into deeper waters. Since Barkai was an experienced diver (he’d worked as a professional diver for the Israeli Navy and as a commercial diver after that), Branch sent him 100 kilometers or so away to Saldanha Bay, a protected coastal kelp ecosystem. “I packed him off to one of the islands we’d been working on, callled Marcus Island,” Branch explained. “I told him, You’re fully qualified as a diver, so I want you to go and do some exploratory dives. Take a look around there, and see if you can see anything interesting.”

It just so happened the area was experiencing a once-in-a-lifetime storm with waves over 18 meters high. “I didn’t know I was exposing him to hell on Earth, and he came back completely shell-shocked,” said Branch. “I think he wondered what kind of supervisor he was getting involved with.” But once things calmed down a bit, Barkai did get in the water, and looked for evidence that the birds nesting on Marcus and other nearby islands were affecting the communities near shore. He didn’t find any—but he did notice something strange.

Near to Marcus was Malgas Island—so named for the gannets, a kind of seabird, which nest there (Malgas is old Dutch for “mad geese”)—which looks entirely similar to Marcus Island from the surface. The seabed, however, told Barkai a very different story. Although they’re just a few kilometers apart, the species he saw “were strikingly different,” he said. West Coast Rock Lobsters (Jasus lalandii) or ‘kreef’ as they are known locally were everywhere around Malgas. Several hundred of them per square meter crowded into crevices and under ledges—there was “basically nothing else.” To find anything that wasn’t a lobster, he had to peek under the holdfasts connecting the kelp to the substrate. There, he found mussels and a few Burnupena papyracea—small whelks (a kind of marine snail).

Around Marcus Island, though, “the bottom was covered with anything but lobster,” Barkai said. A dense mat of mussels lined the benthos, and it was decorated with whelks, sea urchins, and sea cucumbers galore, but nary a lobster to be seen.

Two islands separated by 4 km: one dominated by rock lobsters, the other by whelks (marine snails). In the 1980s, scientists wondered why… pic.twitter.com/OlebLCOyGo

— Trevor A. Branch (@TrevorABranch) June 21, 2017

Further studies at Malgas revealed that the lobsters were so abundant that there was fierce competition for food. “The lobsters were basically fighting for everything that was there. The only thing that usually survived was sponges and seaweeds,” Barkai said, and whatever could hide beneath the kelp. As soon as a juvenile mussel or barnacle tried to settle down, the lobsters scraped it up and ate it. “The lobsters were dominating the benthos,” he explained.

To see what would happen if these lobsters were removed, Barkai put in protective cages with mesh too small for the lobsters to enter. “All other species started to flourish,” he said. “It was clear the lobsters were responsible for the deficit of most life at Malgas Island,” Branch noted.

So… what was different about Marcus? The two islands are so close together, and other than a breakwater connecting Marcus to the mainland, there didn’t seem to be any obvious explanation for this stark difference in the numbers of lobsters. Barkai measured currents, did some sample collection, looked at benthic — or seafloor — structure, but nothing really stood out as an explanation for the vastly different assemblages of species. He and his colleagues even threw a few lobsters in a cage and showed they could survive just fine in the waters at Marcus. The diverse buffet at Marcus should be an irresistible to any lobsters able to find their way there—so why weren’t the hordes at Malgas making the short trip over to feast?

After consulting with Branch, Barkai decided to conduct an experiment—“a very naive and not really well thought out idea,” as he now describes it. He planned to take about a thousand lobsters from Malgas and move them to Marcus to see how they fared.

On the day of the experiment, Barkai was alone in the water, as he was working with a topside crew that didn’t dive (something that would make university dive safety officers extremely uncomfortable nowadays. Of course, this was the ‘80s, and things were different). First, the boat stopped at Malgas, and Barkai collected the lobsters for the transfer. A short 4 kilometer boat ride later, and both he and the lobsters entered the waters by Marcus. And that meant he was the only one to witness what happened next.

“Visibility was great that day, and virtually the entire sea bottom started to move,” he said.

That movement was countless whelks. They started to climb onto the newcomers, sticking to their legs. “I didn’t know then, but they’d started to suck them alive, basically. It was like a horror movie,” Barkai said. “It actually was a bit frightening to watch.” The lobsters simply didn’t know how to respond. They were outnumbered and overwhelmed.

“To my horror, in about 30, 40 minutes, all the lobsters were killed.”

Barkai managed to bring two whelk-coated lobsters back to the surface to show the crew—which is when the first photo in this piece was shot. The bewilderment on his face says everything. On the ship, they carefully pulled the whelks off—over 300 per lobster. “When we removed the whelks from the lobsters, they were empty shells. There was no meat left at all whatsoever. They were simply empty shells,” he recalled. “Basically the only thing that kept them together was the whelks, so the moment we removed the whelks, the lobsters just fell apart.”

But perhaps the most awful part was seeing up close how the whelks had done the lobsters in. They had penetrated every single soft tissue that they could find with their tubular mouthparts—the lobsters’ eyes, joints, anywhere with even a little give. “You could see these very long pipes coming in from the inside of the lobster,” Barkai explained. The poor lobsters—“they didn’t have a chance.”

When he told his advisor what happened, Branch was dumbfounded. “I actually said to him, You know, you must have done something wrong,” Branch recalled. The results were just too unbelievable.

The pair quickly realized that the ravenous whelks—an animal normally on the lobster’s menu—were why Marcus Island had no lobsters. “That was absolutely shattering, because here was a complete reversal of a normal predator-prey relationship,” said Branch—and the paper that resulted, published in Science in 1988, was the first study to document such a reversal.

The caging studies at Malgas had shown that these predatory whelks and other species happily flourished in the absence of lobsters, but they didn’t explain why there weren’t lobsters at Marcus to begin with. So Barkai dug into the history of the two islands, and he learned that Marcus actually was a lobster paradise once—just 20 years prior. But that was before the bay was a marine reserve, and Marcus’ connection to land made it a popular lobster fishing ground. He suspects that the lobsters there were overfished, essentially to local extinction. With lobsters out of the picture thanks to fishermen, everything else was free to settle and grow unencumbered. And they did, until there were so many whelks that the lobsters could not come back.

And it wasn’t just that the whelks became too numerous—they had an ally against any hungry lobsters that might have happened upon them. Barkai had noticed that in this area, this particular species of whelk was covered in an encrusting bryozoan (a somewhat coral-esque animal). He and Branch’s former PhD student, Christopher McQuaid—who was then a postdoc at the University of Cape Town—worked together to show that this bryozoan was protecting the whelks. In feeding experiments, the lobsters generally avoided whelks with the bryozoan on their shells, but happily consumed them if the shells were scraped clean. “It was a much more complicated story than we initially thought,” explained Branch. “Yes it was true that whelks were excluding lobsters. But it is probably also true that they could only secure that ascendancy because they were protected by this bryozoan.”

So the adjacent islands end up in alternative stable states. A video of the whelks overwhelming rock lobsters was aired on South African TV pic.twitter.com/3PZixgBBcw

— Trevor A. Branch (@TrevorABranch) June 21, 2017

Branch and Barkai soon realized they were looking at strong evidence for alternative stable states—the somewhat controversial idea that an ecosystem can exist in very different yet completely stable configurations. “A lot of scientists are skeptical,” said Branch, but further studies on the islands have made a convincing case. Barkai is no longer involved personally in the research—not long after he obtained his PhD, he left academia, though he remains tied to the ocean as the Director for OLSPS Marine, a company that specializes in fisheries data management (he still lives in South Africa, but he said the last time he got in the waters of Saldanha Bay was nearly two decades ago). But Branch (now an emeritus professor at the University of Cape Town) and his colleagues conducted surveys in 2016, and little has changed. “Malgas Island is still dominated by lobsters,” Branch said. “Their numbers are not as great as they were, but nonetheless, there are still large numbers there… And Marcus still has huge numbers of whelks and no lobsters.” So the two very different ecosystems have proven stable for more than 30 years.

And the evidence for alternative stable states continues to mount. After he published the findings in Science, Barkai said he was flooded with researchers noting similar predator-prey reversals, especially involving whelks. “In many fishing grounds, when you don’t have lobster, you get many whelks on the bed instead. So it’s obvious that there is some kind of interaction between the two species—the two species are sort of competing between themselves,” he said. Research in the decades since has also found other incredible examples of predator-prey role reversals, and it’s become clear that they may be more common than previously thought.

Barkai and McQuaid’s findings can also provide insight into the repercussions of a much more recent phenomenon: the sudden proliferation of lobster in the fishing grounds known descriptively as “East of Cape Hangklip.” Before 1989, the area was essentially devoid of lobsters. “Historically, lobsters were regarded as a west coast species in South Africa,” explained Branch. That all changed in the early 1990s. “They had increased very radically to the south, creeping around the tip of the Cape peninsula onto the south east coast,” he said, and by 1995 or so, “the south east coast had accumulated large numbers of lobsters in an area where they had been very rare before.”

And when the lobsters moved in, they took over the benthos, exerting top-down control of the community just like they have for decades as Malgas, Branch’s student Laura Blamey found. “She was able to make comparisons over time by comparing before they invaded and after they invaded, and over space, by comparing areas they had invaded with areas they hadn’t invaded,” Branch said, and she found that in areas now sporting lobsters “things like urchins and mussels and limpets… they’d all been been enormously depleted.” Invertebrates other than lobsters declined by 99.3%, according to Blamey’s research. And once that happened, the algae those species usually kept in check grew unabated. “Kelp abundance increased hugely,” Branch said—by 453%, to be precise.

It might not sound terrible to have more lobsters around, especially since the population on the west coast is currently struggling. Kreef have declined dramatically due to overfishing and have even been recently listed as endangered. And fishers certainly took advantage quickly—the lobsters are now fished heavily in their new southeastern territories.

If you think your fishery has an illegal fishing problem… check out South African abalone pic.twitter.com/u1GoxNxLop

— Trevor A. Branch (@TrevorABranch) December 9, 2014

But the expansion of the lobster fishery has come at the cost of an even more lucrative one: abalone. Another one of Branch’s  students, Elizabeth Day, found that the urchins the lobsters have essentially wiped out are key to the survival of juvenile abalone. “The urchins are sheltering places,” Branch explained, where young abalone can hide until they’re large enough to fend off many of their predators. When urchins disappear, so, too, do young abalone, Day’s research found. “If you remove the urchins, very quickly, the numbers of juvenile abalone crash,” Branch explained. And that means the abalone are getting a double whammy—“the adults are being decimated by poachers, and… the survival of the juveniles is being diminished by the removal of urchins by lobsters.”

Meanwhile, on the western coast, the lobsters have found a way to persist at low densities. So far, Branch said he hasn’t found anywhere where things have shifted the other way—from lobsters to whelks—which is “very surprising,” given that the lobster population is a mere 2.6% or so of its former glory. Barkai was never able to repeat the scale of his experiment (perhaps unsurprisingly, he was unable to get permits to move thousands of lobsters after what happened), so it remains unknown how rare the lobsters must become—or how abundant whelks with their bryozoan bodyguards have to be—before the marine snails are able to turn on their crustacean predators. It’s probably a good thing that such a shift hasn’t happened yet, though, because it’s not clear how to undo this kind of role reversal—or if that’s even possible. There simply isn’t a roadmap for reintroducing lobsters to areas dominated by whelks.

Still, even if the lobsters are keeping the whelks at bay for now, the possibility of a shift to snail-covered seabeds looms as the battle over the west coast lobster fishery heats up. For now, limiting or even halting lobster fishing altogether could help lobster populations bounce back—which is why the World Wide Fund for Nature – South Africa (WWF) faced off in court last week against the Department of Agriculture, Forestry and Fisheries (DAFF) over the total allowable catch limits for the iconic seafood. WWF is arguing that the limits are too high, and that DAFF is ignoring scientific advice—a charge the government disputes.

If WWF’s efforts fail—and they’re right about the catch limits being too high—then the lobsters will become even more scarce in years to come. And if that happens, then Branch and other ecologists in South Africa just might get the chance to learn what it takes for the whelks to take over.

Citation: Bakai & McQuaid, 1988. Predator-Prey Role Reversal in a Marine Benthic Ecosystem. Science, 242(4875): 62-64.
DOI:10.1126/science.242.4875.62

And for those who noticed: No, it’s not a coincidence that the embedded tweets come from a “Branch”—Trevor Branch, a professor at the University of Washington, is George Branch’s son.

It’s estimated that 40% of greenhouse gas emissions come from agriculture, and a substantial portion of that is directly ’emitted’ by livestock. And just last year, climate scientists reported that we’ve actually been underestimating the extent to which the combined belches and flatulence of farmed animals contributes to climate change by 11%. Unsurprisingly, there’s been renewed interest in reducing those emissions, especially considering the demand for livestock is only growing. Now, scientist from the UK report one thing that will help: keep the animals parasite-free.

Livestock’s sizeable contribution to climate change has farmers and scientists working together to find ways to reduce their gas emissions. There are efforts looking into things like revamping feeds or optimizing gut microbes, but so far, there simply aren’t any reliable and affordable ways for farmers to reduce their flock’s flatulence—other than reducing those flocks, period, that is. And with the world’s hunger for meat and milk continuing to grow with an ever-growing human population, that’s not really a solution.

But it turns out that few have looked at how the health of an animal affects the gasses it emits, even though health issues are a constant battle for farmers—and one that’s only going to get worse, as livestock parasites are currently predicted to increase in prevalence as the planet warms. So the researchers took 72 twelve to fifteen-week-old lambs, and infected some of them with a common intestinal worm (Teladorsagia circumcincta). Because the parasite tends to reduce appetite, they created two non parasitized control groups—one allowed to eat whatever they wanted, and one with a restricted diet (80% of the regular amount). And a month and a half later, they put each of these groups of lambs into a special chamber for three days that recorded the concentration of methane in the air.

As expected, the sick lambs seemed a little, well, sick—they gained only 7 g/day while the free-fed controls put on 174 g/day. And they ate less than the free-fed controls, which was exactly as expected. Because they consumed less food, they also produced less methane overall. But when methane production was standardized to food intake, the sick lambs were found to be producing more of the potent greenhouse gas per amount of feed—33% more, in fact. “This is to our knowledge the first study to demonstrate that infectious disease can increase methane yield,” the authors state.

It’s not clear exactly why the intestinal worms caused such a dramatic increase in emissions. Parasites can influence gut microbiota as well as their hosts, but the nature of the study prevented any clear answers as to what about the infected lambs was causing an increase in methane production. “Whilst our results identify a novel phenomenon, they do not reveal the mechanism,” the authors lament in their conclusions.

But whatever the reason, the findings suggest controlling livestock parasites could be a potential climate change mitigation strategy, as healthier animals produce fewer greenhouse gasses. And while many of these parasites are becoming increasingly resistant to veterinary drugs, there are non-medicinal parasite control strategies that are cost-effective. “As the increase in ovine meat production is expected to be highest in developing countries, with restricted access to improved feeds, feed supplements and efficiency gains through genetic selection, parasite control offers a viable and accessible way of reducing emissions,” the authors write.

And the animals probably won’t mind the extra attention to their health, either. After all, these gut parasites tend to be accompanied by things like diarrhea and nausea—which are no more fun for livestock than they are for us.

Citation: Fox et al. 2018. Ubiquitous parasites drive a 33% increase in methane yield from livestock. International Journal for Parasitology, In Press, Accepted Manuscript. DOI:10.1016/j.ijpara.2018.06.001

You know how people say you should aim high? Well, small male dogs have taken that advice to heart. A new study has found that they lift their legs higher when urinating than larger dogs, apparently attempting to appear bigger than they are. 

Dog walkers know that walking a male dog is an exercise in patience, as they want to pause to sniff, lift, and dribble a little urine on what seems every object they walk past. But it’s not the poor dog’s fault; he’s just trying to find out who’s in town and let everyone else know he’s around. Those urine marks are a scent signal that dogs use to communicate with one another. They’re basically renal post-it notes for other dogs to read later. And while it’s true that male and female dogs will use their urine to mark territory and signal their presence to other dogs, males mark far more frequently.

We don’t know exactly what information dogs glean from these uric puddles, but presumably, the unique mix of compounds tells other dogs things like the urinator’s health and breeding status. Since it’s unlikely dogs have any control over exactly what’s in their pee, it’s thought that these scent marks are an honest signal which tells other dogs reliable intel. Except, there is one thing that dogs can control: where they place their pee.

Researchers from Cornell University took small and large dogs on short walks and videotaped them as they made their yellow marks, which were then documented and measured. They also analyzed the tapes later, determining the angles to which the dogs’ lifted their legs. They found that little dogs aimed higher, placing their urine further from the ground for their body size than big ones. And that, the scientists think, might make the marks seem like they’re made by larger dogs. Basically, the little pups are lying about their size.

“Assuming body size is a proxy for competitive ability, small adult male dogs may place urine marks higher, relative to their own body size, than larger adult male dogs to exaggerate their competitive ability,” the authors explained.

Dogs are certainly capable of deception, so it’s definitely possible the small pups are being dishonest. But, the study didn’t account for over-marking—the behavior of peeing on top of another’s —which is thought to be an important part of signaling status. If there was already dog pee on the objects the little dogs were approaching, it’s possible they simply lifted their legs more to mark the same spot. So it would be interesting to see how differently sized dogs react to urine-free areas or manipulated mark heights.

The angle of leg lift could also have nothing to do with the urine signal, and everything to do with the dog itself. Different breeds could simply have different biophysical abilities when it comes to joint rotation and muscular lifting power. So it could just be easier or more comfortable for the small dogs to raise their paws.

Still, the research has raised intriguing questions about the functions of scent marking in dogs and what information is relayed through these sprays of pee. Future studies could shed a lot of light on the lingering mysteries. And while such research is unlikely to win a Nobel Prize, it could certainly put them in the running for an Ig Nobel.

Citation: McGuire et al. 2018. Urine marking in male domestic dogs: honest or dishonest? Journal of Zoology, Early View. DOI:10.1111/jzo.12603

Stemona tuberosa is well known for its use in Chinese traditional medicine, but it’s got a much more intriguing claim to fame. It’s one of less than a handful of plants known to science that engages in vespicochory—that is, it gets predatory wasps to disperse its seeds. It was a strange enough discovery that Gao Chen and his colleagues at the Chinese Academy of Sciences in Beijing wondered how the plants manage to convince the hornets to haul their offspring around. All it takes is the right scent, the team discovered: parts of the plant smell and taste like the insects the hornets normally hunt.

Lots of plants convince wasp relatives—particularly ants—to move their young around. In fact, ant-mediated seed dispersal or mymecochory has evolved at least 100 times in flowering plants and is used by more than 11,000 species. And until Chen and his colleagues took a closer look, that’s how it was thought Stemona tuberosa seeds were dispersed, too. But when Chen and his colleagues decided to study the plant in greater detail, they saw wasps carrying away seeds instead.

They soon realized the predators “pounce” on the protected seeds of the plant (called diaspores)—as “if they were trying to ‘kill’ them by biting, much like their behavior when attacking prey“. Once a wasp rips off a seed, it drags it quite far—an average of over 110 meters away. Often, the helpful hornet eventually stops to rip off most of a fleshy external part called the elasiosome—usually considered the bait for seed-dispersing ants—and takes it with them to their nest (presumably to feed their young). That leaves the diaspore with its seed behind, where ants can discover it and take it to their nests—putting the seeds exactly where they need to be to germinate.

And this wasn’t a rare thing. In their 2017 study, hornets were the only animals that actually took diaspores from the plant and moved them around. They saw ants visit a couple of times, but they couldn’t tear anything off like their bigger cousins could. And that, combined with the relatively short distance the ants moved diaspores when they did find them—a little over a meter and a half on average—suggests their role in seed dispersion is secondary, and perhaps mostly helpful because they drag the seeds underground where they’re safe from seed predators.

But all that doesn’t explain why the species of hornets seen acting as seed dispersers rip off and carry the seed capsules away in the first place. All are predatory species that feed their young other insects, not plant parts. So the research team decided to look a little closer at the fleshy elasiosomes the wasps seemed so interested in.

The researchers collected Asian hornet nests (Vespa velutina) and used them in a series of choice experiments. First, they let them choose between whole diaspores, unprotected seeds, and just those fleshy elasiosomes. They also tagged hornets that attacked the seed capsules to more closely monitor their behavior. But to really look at what smells might be attracting the hornets, they took empty diaspore capsules and made them ‘odorless’ in the lab by stripping potential scents with dichloromethane. Then, they soaked the empty capsules in scent extracts from different parts of the plant and seeds. They also analyzed those scent extracts to determine what they were comprised of, and tested the wasps with synthetic versions. Their results were published this year in the journal New Phytologist. 

When offered whole diaspores, elasiosomes, or seeds, the wasps took no interest in the unprotected seeds—which makes sense, since they’re unable to break through the tough diaspore capsule anyway. But they readily attacked and carried off the whole capsule or just the fleshy bit—suggesting that meaty elasiosome really is the part they’re after. And that was confirmed in the scent choice experiments. The wasps were strongly attracted to Eau de Elasiosome, and in particular, the abundant hydrocarbons the researchers detected in it, like pentacosane, tentacosane, tetracosane, and tricosane. That’s interesting because these compounds aren’t thought to disperse far in the air, begging the question of what draws the wasps close enough to smell them to begin with. The team thinks the bunches of diaspores might look enough like the nest of prey like bees to entice the wasps, but that remains to be thoroughly examined.

Then the team dug even deeper, looking at gene expression in the wasps, and found two chemical sensory genes—VvelCSP1 and VvelCSP2—which were highly expressed in their antennae. Further tests confirmed these proteins bind with the hydrocarbons in the elasiosome extracts, suggesting they’re used to detect the attractive smell.

Previous studies had shown that proteins and other elasiosome components are similar to the “blood” (hemolymph) of ants, so the wasps likely smell the tasty hydrocarbons, take a bite, and believe they’ve found a nice insect meal for their young. And their efforts aren’t unrewarded—Chen and his colleagues found that the elasiosome could actually be nutritious for the young wasps. So, while the plant does trick the wasps into thinking they’ve found a tasty insect, the ruse isn’t harmful—it’s a great example of mutualism. 

Since this fascinating win-win went undiscovered for so long despite the everyday use of Stemona tuberosa in traditional medicine, Chen and his colleagues think there may be a lot more plants out there that use wasps to disperse their seeds. And other work of theirs, which is as of yet unpublished, has found that several other plant families produce similar compounds that could be being used as lures. “We suggest that ‘smelling like prey’ may be not uncommon and may be an underestimated tactic in the dispersal of seeds in other mymecochorous plants,” they concluded.

And if they’re right, that means that our understanding of the ecology of these plants and the wasps they recruit as seed dispersers is sorely lacking. We don’t know how important a food source these elasiosomes are for the wasps’ young, for example, or what impacts the loss of seed-dispersing wasps might have on individual species or entire ecosystems. We’ve been hearing for years about the plight of bees, but perhaps we should be paying more attention to their oft-maligned, sleeker relatives. We’re only just beginning to understand what a world without wasps would look like, and it isn’t pretty.

Citation: Chen et al. 2018. Hydrocarbons mediate seed dispersal: a new mechanism of vespicochory. New Phytologist, Early View. DOI:10.1111/nph.15166

When the 78 year old woman arrived at the hospital, it was clear something was wrong. She’d been suffering from headaches and been in a drowsy fog for weeks. So doctors checked her cerebral spinal fluid, and found it was cloudy and yellow instead of clear. It was brimming with white blood cells, indicating an infection. This, alongside a positive antibody test, led to a diagnosis of angiostrongyliasis—an infestation of the parasite rat lungworm (Angiostrongylus cantonensis).

As the name implies, rat lungworms usually set up shop in rat pulmonary arteries. But their complex lifecycle involves spending time in an intermediate host like a snail before making a home inside a rodent. If we happen to eat that infected host before a rat does, they can end up inside us instead, where they can get lost and cause serious infections in other places. The parasites are most dangerous when they make their way into the brain, causing swelling and inflammation—like the woman was experiencing. But the woman hadn’t been eating snails.

A few weeks later, her 46 year old son was also admitted, and he, too, was diagnosed with angiostrongyliasis. Both were cured after a few weeks on an antiparasitic and steroid. But the question remained as to how they became infected—he wasn’t eating snails, either. But, it turned out, both he and his mother had been consuming raw centipedes from a local market. And that led the doctors to question: could centipedes also carry rat lungworm?The answer, they discovered, is yes.

There’s no reason to initially suspect centipedes would host rat lungworm. The parasites use mollusks as intermediate hosts, and they develop from their first larval form into third stage larvae (the ones that infect us) in them exclusively. Centipedes aren’t even remotely closely related to the snails and slugs the worms usually target, and most parasites are pretty particular about their hosts. Things that live in mollusks don’t usually survive in arthropods, and vice versa.

But, the worms can at least live for a little while in other species—some infections in the past have occurred from eating prawns and other animals that live around the worms’ usual hosts, which led scientists to conclude lots of species can serve as substitute or paratenic hosts. A worm doesn’t develop further in these less-than-ideal hosts, so it has to be already third stage, but it doesn’t die either. And it can still be passed on to its final host if the substitute host is consumed. So it’s possible that centipedes could also act as substitute hosts. Or they could even be true intermediate hosts—until now, no one thought to look.

That’s in part because human infestations of rat lungworm often occur when people eat unwashed vegetables, thus inadvertently consuming small snails or slugs hosting the worms raw—and accidental centipede ingestion isn’t really a thing. It’s pretty hard to overlook a finger-sized centipede on your lettuce leaf.

You might intentionally eat a centipede, of course. While centipedes aren’t common fare for most in the Western world, they are frequently served as street food or in soups in Chinese and other Asian cultures. They’re also dried and powdered for Chinese medicine. But however they’re prepared, they’re usually cooked—which kills the parasite. “We don’t typically hear of people eating raw centipedes, but apparently these two patients believed that raw centipedes would be good for their health,” explained Lingli Lu, who works in the Department of Neurology in Zhujiang Hospital, in a press release.

But it’s one thing to suggest the centipedes were the source, and another to confirm it. The researchers wanted to detect the parasites inside the centipedes directly. So they bought 20 centipedes from the same market in Guangzhou where the family had purchased theirs (animals that were locally caught in China’s Guangxi Province). They then examined the centipedes carefully before mashing them up for DNA extraction. Since the parasites are tiny and hard to identify to species visually, they used DNA analysis to get a clearer positive or negative result.

And they found them. An average of 56 larvae were found per centipede, and rat lungworm DNA specifically was detected in 7 of the 20 centipedes they’d purchased.

Still, the team wasn’t sure if the larvae had ended up there because the centipedes ate an infected snail (thus serving as substitute hosts), or whether the centipedes themselves were serving as intermediate hosts. They tried to infect centipedes with first stage larvae to find out, but all the centipedes died. While that doesn’t make it seem likely they’re intermediate hosts, it’s also possible the experiment didn’t perfectly mimic a wild infection, so the question is still open.

Unfortunately, the test doesn’t tell us how long they can serve as substitute hosts, even if they aren’t true intermediate ones—which makes it difficult to understand how centipedes might fit into the larger picture of the parasites lifecycle or affect our risk of infection. While rat lungworm is native to Asia, it’s made its way around the world, and has become a big problem in places like Africa, Hawaii, the Caribbean, and most recently, the southern United States (especially Louisiana and Florida). And of course, these areas are also home to centipedes—pretty much everywhere somewhat warm is—so it’d be really great for future research to get a better understanding of how these animals interact with rat lungworms.

But, given the team’s findings, it seems that regardless of how they end up with third stage larvae inside them, centipedes are quite capable of transmitting the worms to us. So, moral of the story: don’t go around eating raw centipedes…. Toast them up nicely first.

Citation: Wang et al. 2018. Eating centipedes can result in Angiostrongylus cantonensis infection: two case reports and pathogen investigation. Am J Trop Med Hyg, online early. DOI:10.4269/ajtmh.18-0151

Coconut crabs (Birgus latro) are gigantic land-dwelling crabs found on islands throughout the Indo-Pacific. They can live for decades, and can grow to be more than 3 feet wide (legs outstretched) and weigh in at more than 6 pounds. So that name isn’t because they’re the size of a coconut—it’s because they can actually tear open coconuts to eat their tender meat.

“If a coconut falls out of a tree, they’ll clamp onto it on the top and then drag it back to their husking ground,” explained Victoria Morgan, a PhD Candidate in the Department of Evolution and Ecology at University of California, Davis. You can always tell where a crab hides out by the piles of coconut husks lying around.

And it just so happens that out these massive, tree-climbing crabs come in multiple colors. They start out white as juveniles, when they act like other hermit crabs and don a protective shell. Then, as they mature and grow, they turn either red or blue. Really, really red, and really, really blue. “It’s weird that the colors are so distinctive,” Morgan explained. Stark color differences within a species, or color polymorphisms as scientists call them, are found in other crab species, but they’re generally in young animals.

You’d think that kind of striking color difference arose for some evolutionary reason. Luckily, that’s just the sort of colorful mystery that fascinates Tim Caro, evolutionary ecologist at UC Davis. So he asked Morgan — who was studying other land crabs at the time — to help him uncover what’s going on.

“We wanted to test some of the more traditional explanations for different colors in nature,” said Morgan. Lots of species have different colors due to sexual selection, for example, as different male and female colors can happen if females are choosy about their mate’s looks or if males compete. Or it could be a simple size thing, like if shell thickness leads to one color (which is essentially what happens in the shore crab Carcinus maenas). Or the colors could provide unique advantages in different environments, like is the case with pepper moths.

So to tease apart the different possible explanations, the duo went to three different locations—the Pemba Island archipelago and Chumbe Island off Tanzania, and Christmas Island, an Australian territory south of Indonesia—and collected 325 crabs. For each, they recorded sex and took all sorts of physical measurements of the animals, including how strong they could pinch. They also when and where each was found. And they even did a quick crab personality test by noting their “disposition to being handled on a 5-point subjective docility scale”—which, for the record, goes from being shy and still to “aggressive (repeatedly grasps the holding bucket and rapidly extends abdomen)”.

On each of the islands, between two thirds and three quarters of the crabs were red. Most of the crabs were males in general, but there was no correlation between color and sex. There were also no correlations to weight or other measurements of size. And there was no correlation between pinching ability and color, either. They did find that bigger crabs were more docile (which, when you’re talking about a >6 lb crab, is probably a good thing)—but color didn’t matter at all. The only slight hint they found was that the blue crabs seemed to be more common near the ocean while the red ones more common inland, but the association wasn’t significant.

“What we found to be most surprising was that none of the traditional hypotheses explain this system,” Morgan said, laughing. In a couple weeks, though, Morgan and Caro are headed back to Tanzania. They hope to up the sample number to see if the habitat difference becomes significant, and to try some new ideas.

They want to observe them mating, for example, to determine if the different colors seem to prefer mating with one of their own. And they really want to look at the crabs’ DNA. “The first step is to figure out what gene is responsible for the coloring in these crabs,” she explained. The team has a hunch that it might have something to do with the expression of a protein called crustacyanin  (which is how blue lobsters get their smurfy hue). In addition, they want to look at the expression of genes in the crabs’ eyes to determine whether they can even see the two colors. Some crustaceans have excellent color vision (like mantis shrimps), but that may not be the case with the coconut crab. They’ll also look at the crabs’ genomes to get a better idea of how often the two color morphs are interbreeding (especially if they don’t find too many mating pairs).

There has to be something keeping both colors around, Morgan said — otherwise, over time, one would just disappear. “You’d expect that it’d swing one way or the other, so that you’d end up with all red crabs or all blue crabs,” she said. “The fact that we see both morphs across the different parts of their range indicates there’s something that’s driving them to keep the polymorphisms present in their population —we just haven’t figured it out yet.”

In the meantime, these weird, colorful crabs will continue to eek out their existence on the islands in the Indo-Pacific, chowing on their coconuts and… well, actually, about that.

They’re not just coconut-eaters. “They tend to eat everything,” Morgan explained. She’s even seen them digging through trash bins. “And their sense of smell is amazing. Whenever I was cooking on the island, they’d come from all over the island to try to eat what I was eating,” she said. They’d even try to scale the gate of her kitchen area to get a taste, which she admitted was “a little creepy.” And they often eat at night, so, they’re basically the crustacean version of a raccoon.

In fact, just last year, biologists confirmed that they not only will eat pretty much whatever, including carrion if they find it, they can climb trees and kill full-grown birds — snapping a brittle booby bone is apparently easy for those powerful claws.

But despite their infamous taste for flesh,”they usually keep to themselves,” Morgan explained. It’s not like they’re chasing after you — they usually just kind of meander around slowly, “and they typically try to escape when approached by humans,” she noted. “I don’t want people to think that they’re a real threat to human safety.”

In fact, it’s the crabs’ safety that’s threatened if anything. “It’s very likely that they’re actually an endangered species due to population pressures from human consumption,” said Morgan (they’re “data-deficient” according to the latest IUCN update, but their populations are likely declining). These slow-growing crabs take at least 5 years to reach maturity, several decades to become fully grown, and can live almost as long as we do. And that means they’re just not great at rebounding if their numbers crash. So if we keep messing with these amazing animals the way we are now by eating them and destroying their island homes, we may never understand their colorful lives.

I’m throwing this young coconut crab (Birgus latro) and his fancy plastic hat into the ring for the #CuteOff pic.twitter.com/abYQ1fuAER

— Jake Buehler (@buehlersciwri) September 1, 2015

Citation: Caro & Morgan, 2018. Correlates of color polymorphism in coconut crabs Birgus latro. Zoology 129: 1-8. doi:10.1016/j.zool.2018.06.002

The sight of dozens of butterflies congregated in one spot might be beautiful, but if you know what they’re actually doing, you might not want to get too close. When butterflies get together like this, it’s usually to slurp up some nutritional goodies from an unexpected source—like, oh I don’t know, animal pee.

This behavior is often called “puddling” or “mudding”, though the insects don’t just suck on damp earth. To get missing nutrients like sodium which aren’t common in the nectars they usually drink, they’ll sip up turtle tears, fecal fluids, and even the juices from rotting corpses. So they’re certainly not above a nice little pee puddle if it contains what they’re looking for—and it does. There’s sodium in basically all urine because it’s used to draw the fluid from the body, though the amount varies.

Work by @andy_manu_peru, Ross McLeod et al suggests that carrion-feeding butterflies will be a powerful additional indicator of impacts of human disturbance on tropical biodiversityhttps://t.co/rhlcwHZb5k pic.twitter.com/Xbdth9l6TO

— UofG BAHCM Institute (@IBAHCM) December 5, 2017

Other insects—like biting flies—are known to be drawn to urine odor compounds because they indicate the presence of their meals. Since urine is a logical source of sodium, Michael Bodri from the University of North Georgia wondered if puddling butterflies could smell it. So he set up a baiting experiment using urine from three species with different diets.

Cow urine, which was obtained from a local farm’s heifer, was used as the representative herbivore pee. Mountain lion urine bought from Pee Mart (which is a serious, totally legitimate store) was used as the carnivore sample. And human urine, obtained, well, from the most obvious source—the author himself—was the chosen omnivore. The pees were all preserved with glycerin and slightly dehydrated to prevent bacterial contamination, and then placed in 10 ml volumes in traps or sandy bait stations to see how many butterflies stopped by for a sip.

It only took a few minutes after the urine was poured into the sand for butterflies to appear—a clear sign they could smell the pees. In total, the traps caught butterflies from 7 species in 3 families—all normally nectar drinkers. But there was no doubt what pee the butterflies preferred: 97 of the 117 butterflies observed feeding on the urines were drinking the mountain lion’s pee. Only 14 and 6 butterflies tasted the omnivore and herbivore urines, respectively.

That’s particularly interesting because the urines from all three animals all have similar levels of sodium (about 100 mmols/L). So what was it about mountain lion urine that was so alluring? Bodri doesn’t know. In fact, it’s unclear how puddling butterflies ever find their “puddles”. Some researchers have suggested that they can smell sodium—which would make sense, if that’s what they’re looking for—but sodium itself isn’t very volatile, so it seems unlikely that enough of it would have lifted into the air for the butterflies to detect. It seems more likely that some kind of urine odor is the draw, but since Bodri didn’t do a full chemical profile of the urines or their odors in this study, it’s not clear what sets the cat’s pee apart (all urines were reported as highly concentrated with specific gravities above 1.035; the relative concentrations of the three were not reported).

Given that each dietary group (herbivore, omnivore, carnivore) only had one representative pee, it’s still too early to say they prefer carnivore urines in general. Future work should compare their interest in a taxonomic diversity of carnivores to make sure it’s not something special to felines or even cougars. And to really understand what the butterflies are flocking to, future studies might try isolated urine components to see if the butterflies really are drawn to the salt or something else.

Still, this initial work has laid the foundation for all kinds of research on lepidopteran attractants. Understanding the urine preferences of butterflies might seem strange, but it can tell us a lot about how the animals sense their world. Since the traps were all visually the same, the study shows that they really do seek out puddling spots by what they smell rather than what they see. And ultimately, gaining a better understanding of how they perceive the world not only helps us understand their behavior—it may also provide key insights into how to keep these animals alive and happy so that generations to come can ooh and ahh at the fantastic site of dozens of beautiful butterflies crowding together to drink some pee.

Citation: Bodri 2018. Puddling Behavior of Temperate Butterflies: Preference for Urine of Specific Mammals? Journal of the Lepidopterists’ Society 72(2):116-120. doi:10.18473/lepi.v72i2.a3

The process of domestication fundamentally changes an animal’s looks and behavior. Floppier ears and a loss of fear of humans, for example, are nearly universal in domesticated species. Now, researchers have learned what domestication looks  like in the brain—at least, for rabbits. 

It’s not exactly clear when rabbits were converted from one of nature’s most skittish animals into the soft, snuggly buddies so often chosen as class pets. But somehow, selective breeding led to bunnies that have lost most of the anxiety their relatives rely on to survive. And it only makes sense that such a shift would show up in their brains.

The research team based largely in Sweden, Spain and Portugal had looked at the genomes of wild and domesticated rabbits before, and found distinct differences in genes associated with brain and neural development. So they decided to look for what those genetic changes might be actually doing.

“No previous study on animal domestication has explored changes in brain morphology between wild and domestic animals in such depth as we have done in this study,” explained Leif Andersson, a geneticist with Uppsala University in Sweden and coauthor on the new paper published this week in Proceedings of the National Academy of Sciences, in a press release. To get this new data, the team raised eight wild rabbits and eight domesticated rabbits (from three breeds) under similar conditions until they were fully grown. Then, they imaged their brains using an MRI.

The brains of the domesticated rabbits were smaller for their body size, but that wasn’t surprising, as similar brain ‘shrinkage’ has been noted for other domesticated species. What really stood out were the other changes to the brain. “Domestic rabbits have a reduced amygdala and an enlarged medial prefrontal cortex,” explained first author Irene Brusini, a PhD student at KTH Royal Institute of Technology in Sweden. When corrected to brain size, the domesticated rabbits’ amygdala’s were roughly 9-10% smaller, while their medial prefrontal cortices were about 11-12% bigger. These are areas of the brain involved in sensing and processing fear, so the authors believe their change in size likely underlies the domestic bunnies’ characteristic friendliness.

And that wasn’t all—there was also a reduction in white matter—the nerve fibers responsible for connecting regions of the brain into functioning circuits—in the domesticated rabbits. “The reduced amount of white matter suggests that domestic rabbits have a compromised information processing,” said Mats Fredrikson, a professor at Uppsala University and one of the paper’s senior authors. And that, he believes, might explain their slower reaction times and generally calm demeanor.

The research team didn’t really expect the magnitude of the differences in the brains—they thought the changes might be too subtle to be seen. But there was no denying the clear differences between the brains, especially since the analyses were conducted blindly (the scientists analyzing the images did not know which brains were wild and which weren’t).

A previous study on mink also found differences in the sizes of different brain parts between wild and domesticated versions (including a reduction in white matter in domesticated versions), as have similar studies in other species, but they lacked the resolution of MRI. These much more detailed data give scientists new insights into how domestication really happens—and it’ll be especially interesting to compare these results with future detailed studies of other domesticated animals to see if all domesticated brains share similar features, or if the process varies dramatically by species.

Citation: Brusini et al. 2018. Changes in brain architecture are consistent with altered fear processing in domestic rabbits. PNAS. doi:10.1073/pnas.1801024115

The conspicuous colors of poison frogs are presumed to be a warning. Indeed, vibrant patterns so often signal toxicity that biologists even have a special term for them: aposematic coloration. But, weird as it might sound, new research suggests that radiant skin patterns might help these frogs stay hidden, too.

Poison frogs are armed with some of the planet’s most potent toxins. The most deadly is the golden poison frog (Phyllobates terribilis)—one frog’s worth of toxin is roughly enough to kill 10,000 mice or about 10 people, though estimates vary. It makes sense for it and other frogs to let potential predators know that eating them is a bad idea, and most do seem to advertise their toxic nature through bright, colorful patterns. The dyeing poison frog (Dendrobates tinctorius) is no exception: its legs are a brilliant blue with black spots, while its back has swirls of bright yellow.

It seems counterintuitive at best that such vivid patterns could serve as camouflage, but that’s exactly what researchers from the University of Bristol found in their study. First, they took pictures of the frogs in their natural habitat in French Guiana, and then tried to “spot” the frogs using computer models of different animal visual systems. In their models, the frogs were easy to spot close up. But as the simulated eyes moved further away, the patterns started to blend into the background.

But computers aren’t perfect, so they continued with two studies that tested real eyes. In the first, plastic frogs were placed in the wild on one of four backgrounds—leaf litter, a photo of leaf litter, natural soil, and a colored paper square. The fake frogs were either pattered yellow and black, all yellow, or a completely cryptic brown and black. Both the frog’s natural coloration and the designed cryptic patterns lessened the rate at which the faux frogs were attacked by birds, but only when on the leafy backgrounds.

They also had people try to spot different frog patterns. Images of frogs with the generated natural and unnatural patterns were placed on photos of leaf litter randomly, and scaled for three detection distances. Since participants had to click on the frog, the researchers could clock how long it took them to find it as well as the spotter’s accuracy. And they found that up close, it was easy for people to spot the yellow and black frogs. But they were harder and harder to see with distance, becoming as hard to distinguish as intuitively camouflaging patterns.

That led the authors to conclude the fogs are basically getting the best of both worlds: they’re easy to see up close, so their color can serve as a warning. But they’re hard to spot from far away, just in case anything did want to tempt fate by eating them. “Certain predators have evolved tolerance of toxins that would be deadly for humans, and some individual predators may have not encountered the warning signal prey before,” explained lead author Jim Barnett in a press release. “So, color patterns that could be distinctive close-up, but work as camouflage from a distance, would provide a clear advantage.”

They think what’s happening is that because the frogs use colors that aren’t present in the background—those bright yellows and blues—they stand out if you’re near enough to see them. But as your eyes move further away, the colors start to blend together, and the frogs’ average color is basically the same brown as the leaf litter they hang out on.

Further research will be needed to see if aspects like lighting also play a role, as well as whether other species, especially other toxic ones, have evolved similar ‘distance-dependent coloration’. But the implications of such research stretch well beyond understanding frogs—as one co-author pointed out, these data could help design better camouflage patterns for our uses, like for use by the military.

Who said winter is sad? @Mariaescote no! pic.twitter.com/qPq3n1k742

— Jameslussò (@alvarez_1994) February 26, 2013

Added bonus: our troops would look so much more impressive if they were decked to the nines in poison frog patterns. Maybe they could ask María Escoté to design the new uniforms!

Citation: Barnett et al. 2018. Distance-dependent defensive coloration in the poison frog Dendrobates tinctorius, Dendrobatidae. PNAS, Early View. doi:10.1073/pnas.1800826115