Does Size Matter? Jellyfish Venom Capsule Length Association with Pain

Japanese Sea-Nettle

Since the PLOS San Francisco office is a quick car ride from the Monterey Bay Aquarium, so many of us at PLOS have been captivated by jellyfish movements. They are simply mesmerizing to watch as they travel through the water. Unfortunately, close proximity to a jellyfish in open water can be nerve-wracking – contact with their tentacles triggers the discharge of venom. It only takes three milliseconds for jellyfish venom to transfer to a victim, which is one of the fastest movements in the animal kingdom. This sting can result in persistent pain and swelling, and sometimes even death.

Unless you know a good deal about jellyfish, it’s hard to tell just by looking at them whether they are extremely poisonous or relatively harmless. Unfortunately, size and shape are not necessarily indicators of whether they are dangerous. However, scientists believe there may be other ways to tell how much a given sting may hurt.

A jellyfish stings by discharging a tubule shaft contained inside what’s called the nematocyst, the stinging organelle of the jellyfish—which pierces the skin and injects the venom. The authors of a recently published PLOS ONE study were curious as to whether the length of the nematocyst capsules was a factor in the amount of pain felt after a sting.

The researchers collected four different species of jellyfish: Japanese sea nettle, a species of box jellyfish, the habu-kurage (another type of box jellyfish), and moon jellyfish from different locations in Japan. Habu-Kurage and box jellyfish are known to have extremely painful stings, Japanese sea nettle are moderately painful, and moon jellyfish are pretty much painless. Scientists removed and froze the tentacles from all four species immediately after collection. Later, they shook the tentacles in a saline solution for five minutes to release the nematocyst from inside the tentacle.

They then suspended the nematocyst in the saline solution and placed it under a microscope on a flat, glass slide, while holding another glass slide above it. If the nematocyst did not discharge the venom capsule automatically, they lowered the top slide down until it did, as touch is often a trigger for the release of the venom. The microscope camera photographed the nematocyst before and after the venom was released. Following the release, the scientists measured the nematocyst capsules in micrometers. From there, they identified which jellyfish had the longest or shortest nematocysts. One of the habu-kurage’s nematocyst capsules from Fig. 3 in the paper is pictured below.


The authors found that each species had approximately the same number of nematocysts per gram of tentacle, but that the species with the more painful stings tended to have longer capsules. The species from longest to shortest nematocysts were the box jellyfish, habu-kurage, Japanese sea nettle, and moon jellyfish.

The two jellyfish with the more painful stings, the box jellyfish and habu-kurage, also had the highest average percentage of nematocyst tubules longer than 200 micrometers, with 80% and 91%, respectively; while the somewhat less-painful Japanese sea nettle had only 6% of their tubules longer than 200 micrometers, and the practically painless moon jellyfish had 0%.

When it comes to sizes, importantly, the network of intersecting nerves beneath human skin, also known as the sub-epidermal nerve plexus, is 100 to 200 micrometers below it, and the authors suspect that longer nematocysts can more easily reach these nerves, which might explain why box jellyfish and habu-kurage deliver more painful stings to us than the other species tested.

Nematocyst Depth

The image above, also in the paper, demonstrates the length of the jellyfish nematocyst capsules and how far they could potentially penetrate into the skin. X represents tubule lengths less than 200 micrometers, Y represents tubule lengths between 200 and 600 micrometers, and Z represents tubules that are longer than 600 micrometers (found in the box jellyfish), which can potentially reach all the way to the innermost layer of our skin, what’s called the hypodermis.

The researchers did find that the box jellyfish had longer nematocyst capsules and a more powerful toxin than the habu-kurage, but the habu-kurage is considered much more hazardous to its prey and to humans. The authors posit that this may be because habu-kurage has many more tentacles that are much longer than that of box jellyfish, which could mean that more toxin is injected into the body of its victim per sting. Regardless of the additional research that needs to be done to see why the habu-kurage can cause so much pain and can sometimes even be fatal, it would best be safe to swim far away from those tentacles’ reach.

Citation: Kitatani R, Yamada M, Kamio M, Nagai H (2015) Length Is Associated with Pain: Jellyfish with Painful Sting Have Longer Nematocyst Tubules than Harmless Jellyfish. PLoS ONE 10(8): e0135015. doi:10.1371/journal.pone.0135015

Figures: “Japanese Sea Nettle” by Kenny Louie, Figure 3, Figure 4

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“Elementary, My Dear Watson!” Clues Revealed About an Ancient Case of Leprosy

Unidentified remains found in the English countryside and all signs point to the untimely death of a young man. Researchers examined the bones of a supposed victim, which showed signs of leprosy, to search for clues about the arrival of the disease in Britain and its eventual spread throughout Europe.


The above results, reported in a recent PLOS ONE study, read a bit like a Holmes mystery.

The authors examined a skeleton found in Burial GC96, a grave excavated in the early 1950s near Great Chesterford, England (see a sketch of the contents of the grave site in the image above.) Archaeologists explored the site after the area was mined for gravel, and the skeleton discovered in Burial GC96 was moved to the Department of Archaeology at the University of Southampton. Like good detectives, the authors collected evidence to try to answer the three W’s:

• Who was the victim?
• What was the cause of death?
• Where did the victim come from?

The authors gleaned some immediate information regarding the “who.” The skeleton’s head and pelvis shape revealed the victim was male. The stage of his bone growth, as well as the wear on his teeth, indicated that he was somewhere between 25-35 years old when he died. Carbon-14 dating confirmed that he was buried sometime between 400 and 500 A.D.

As to finding out more about the cause of death, the researchers closely inspected the skeleton and found that holes were forming in his bones, and that new, jagged bone was growing to make up for this weakening. This irregular bone growth was likely caused by the disease that could have led to the victim’s premature death. The holes and lesions are visible in the bones of the victim’s foot, pictured below. According to the authors, while these symptoms are characteristic of leprosy, their presence alone is not enough to show that the victim suffered from the disease, as they could also indicate other illnesses, such as diabetes.


Then, things got interesting. To obtain further evidence, the authors analyzed lipid biomarkers, which can indicate the presence of some diseases. In this case, the analyses confirmed that the skeleton suffered from leprosy. The strain of the disease plaguing our poor victim was a type called 3I, which would later spread throughout Southern Britain and Europe, and eventually across the Atlantic to the Americas. (The 3I leprosy strain is still found in some southern states in the US.) More interesting still, the victim’s case of 3I leprosy may be the earliest known case in Britain to be confirmed by both carbon-14 dating and DNA analysis.

With the evidence and assay results in hand, the authors attempted to answer their final research question: Where did the victim come from?

The answer seems to lie in his teeth. Researchers know that when we drink water, isotopes of oxygen and strontium in it find their way into our bodies, and the particular isotopes found in the water depend on its geographic origin. While isotope analysis was not reliable enough to allow the researchers to pinpoint the victim’s exact birth place, the results did suggest that he was not native to the South of England. In fact, the isotopes in the skeleton’s teeth were most similar to those found in the ground and rainwater in Northern Germany or Denmark. According to the authors, these findings may provide clues that might help us understand the origins of leprosy in Britain, and the disease’s eventual spread across Europe.

Though the authors’ scientific sleuthing provided clues, we can’t yet neatly close the case on the arrival of leprosy in Britain and its spread throughout Europe. While evidence points to a Scandinavian origin for the 3I leprosy strain, we still don’t know where exactly it came from or how it arrived in the Americas. These mysteries will continue to unravel as archaeological detectives puzzle over the case.

Citation: Inskip SA, Taylor GM, Zakrzewski SR, Mays SA, Pike AWG, Llewellyn G, et al. (2015) Osteological, Biomolecular and Geochemical Examination of an Early Anglo-Saxon Case of Lepromatous Leprosy. PLoS ONE 10(5): e0124282. doi:10.1371/journal.pone.0124282

Images: Figure 1, Figure 3

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Printing the Past: Putting a Prehistoric Mystery Lizard Back Together Again


The size, shape, and solidity of an egg can tell us a lot, but until we can see inside, there is still an opportunity for surprise. Unfortunately, when you have an ancient fossilized lizard egg, you can’t just crack it open and hope that everything is complete and identifiable. With recent advances in 3-D scanning and printing technology, scientists can now more easily see the contents of an egg without actually opening it. Using this approach, researchers may have made some unexpected discoveries about lizard reproduction.

As a group, lizards show remarkable reproductive variation: some species give birth to live young, while others lay eggs. The authors of a recently published study in PLOS ONE decided to look into the origins of lizard egg-laying after digging up seven ancient fossilized lizard eggs in Thailand from the Early Cretaceous period. The area where these eggs surfaced is thought to have been isolated from the main continent, as suggested by the remains of many unusual ancient creatures that are found there.  To find out more about the insides of these eggs, the authors used penetrating wave technology, called tomography, to obtain detailed scans of sections of each egg. Then, they stitched these image sections together to create 3D models of the eggs, inside and out. From these models, the researchers virtually extracted pieces of the embryo and “rebuilt” the unborn lizards.


The image above shows the reconstructed 3-D images of two of the fossil eggs and all the bones that are enclosed in them.


Above are the virtual images of the skulls and jawbones of the prehistoric lizards that the authors pieced together from the most well-preserved eggs.

The authors also took a close look at the eggshells themselves. Using light and X-ray technology, they were able to create in-depth pictures of the eggshell and learn more about its characteristics. These eggs had shells that were rigid, which meant that they may have been stronger than your average shell and unlikely to shrivel up after hatching. This is likely why they were strong enough to become fossilized. The authors think that the eggshells’ rigidity can be explained by the crystal pattern of the main chemical compound, calcium carbonate, found in the shells. Below are multiple close-up images of the eggshell in different types of light and from different portions of the shell. The crystal pattern is most prominent in panel D.

journal.pone.0128610.g008 (1)

Based on observations of modern lizards, scientists thought that the only lizard to come from rigid eggshells was the gecko. However, through the analysis of the fossilized eggs in this study, the authors found that these lizards may not be from the gecko family, but are likely from the Anguimorph family that includes komodo dragons. While the eggshells have many similarities to the modern gecko egg, they did not have the typical solid masses of minerals that are found in gecko eggs. Also, the crystal pattern of calcium carbonate is arranged differently than that of the modern gecko egg.

The eggs alone do not contain enough information for the authors to verify the exact species of lizard contained inside. While the lizards in the fossilized eggs may be an undiscovered or “new” type of lizard, the unborn remains need to be compared with adult remains before this can be confirmed. Although adult remains have not yet been discovered, these exceptionally preserved embryos may be key to cracking the surface of lizard reproduction.

Citation: Fernandez V, Buffetaut E, Suteethorn V, Rage J-C, Tafforeau P, Kundrát M (2015) Evidence of Egg Diversity in Squamate Evolution from Cretaceous Anguimorph Embryos. PLoS ONE 10(7): e0128610. doi:10.1371/journal.pone.0128610

Figure: Figure 2, Figure 3, Figure 4, Figure 8


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The Nose Knows: Oriental Honey Buzzards Use Nose and Eyes to Forage for Sweet Treats


Winnie the…Buzzard? The Oriental honey buzzard Pernis orientalis feeds primarily on honey and bee or wasp larvae. But how do they find their food?

In the winter, thousands of Oriental honey buzzards migrate to Taiwan to forage. These migrating honey buzzards especially target apiaries for a tasty treat not found in nature: “pollen dough.” Beekeepers make softball-sized balls of pollen dough from pollen, soybeans, and sugar to feed their bees in winter when flowers are scarce.

The unusual appearance of pollen dough (bright yellow, perfectly round, and very unlike honeycombs or bee larvae) led these PLOS ONE authors to hypothesize that the honey buzzards might be using their noses (olfaction) in addition to visual sightings to identify the dough as food. Olfaction doesn’t appear to be very ecologically important to other raptor species, so the possibility that honey buzzards use their sense of smell as well as vision to find food is exciting.

Specifically, the authors asked:

  • Can honey buzzards distinguish between visually identical doughs missing a specific food ingredient (pollen, sugar, or soybeans)?
  • Are buzzards influenced by the pollen dough’s color?

To test these hypotheses, the authors ran a series of field experiments.

In their first experiment, the authors focused on the buzzards’ ability to smell specific ingredients in the pollen dough—specifically pollen, one of their sources of nutrition in the wild. To do so, the authors varied the pollen, soybean, or sugar content between two dough samples, but kept the appearance of both samples identical in terms of texture, brightness, and color (yellow).

In the second experiment, the authors examined the buzzards’ reliance on visual cues by varying the colors of two potential dough samples between yellow, black, and green. They kept the ingredients of both dough samples the same.

The third and final experiment was a variation on the first experiment, where the dough was dyed black instead of yellow.

The results from experiment 1 revealed that buzzards strongly preferred pollen-containing doughs.

In the second experiment, all buzzards exclusively chose to eat yellow dough instead of black or green dough as shown in the graph below.yellow dough graph 1

The results from the third experiment backed up experiment 1’s results, with buzzards again preferring to eat pollen-containing dough over non-pollen-containing dough, even though it was dyed black, as shown in the graph below.

black dough graph 2

Based on the results from experiments 1 and 3, the authors posit that honey buzzards prefer pollen-containing dough over dough with no pollen added. It seems probable that the ability to select between two visually identical samples is based on the buzzards’ ability to smell the differences.

The authors also looked at the olfactory receptor (OR) gene repertoire size in the honey buzzard’s genome. The number of different scents a species can distinguish is linked to its number of OR genes. Their gene analysis showed that the Oriental honey buzzard has the largest OR gene repertoire of the diurnal raptors—almost five times as large as the OR gene repertoire of peregrine falcons or golden eagles!

Taken together, these results suggest that the Oriental honey buzzard uses both olfaction and color vision when foraging for food. Additionally, the results of experiment 3 (where all dough samples were colored black) suggest that olfaction might predominate over vision in cases where the two senses seem to conflict.

While more work still needs to be done to discover the extent of the role olfaction plays in Oriental honey buzzards’ feeding strategy, it seems clear that in this case the nose (or beak!) knows.

Citation: Yang S-Y, Walther BA, Weng G-J (2015) Stop and Smell the Pollen: The Role of Olfaction and Vision of the Oriental Honey Buzzard in Identifying Food. PLoS ONE 10(7): e0130191. doi:10.1371/journal.pone.0130191

Images“Oriental Honey-buzzard Pernis ptilorhyncus” by Tsrawal, Figure 3,  Figure 4


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Introducing the New PLOS Video Shorts

In 2011, PLOS ONE launched a series of short instructional videos to help our authors, reviewers, and Academic Editors navigate Editorial Manager, our online submission system. We recently updated and expanded these video shorts to provide a resource for PLOS authors, reviewers and Editorial Board members. The new PLOS ONE video shorts playlist is below.

If you have a question about how to use our Editorial Manager system, whether it is how to select a reviewer or submit a revised manuscript, we highly recommend that you check out our instructional videos for a step-by-step guide. You can view the video shorts on the EveryONE blog and on the PLOS Media YouTube channel.

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We Want the Funk: The Ups and Downs of Wild Microbes in Beer


Funky, floral, complex. No, this is not a description of a piece of vintage wallpaper. These are some of the words that are used to describe the enormous variety that exists within the world of beer. Whether you are enjoying the outdoors on a sunny day or sitting by the fire on a cold, winter night, there is a beer to match every occasion. In honor of this tasty drink, we have put together a compilation of PLOS ONE articles dedicated to the study of beer and the yeast and bacteria that mold its complexity.


“Spontaneity is a meticulously prepared art” – Oscar Wilde


Figure 4 of the published article shows the different isolates found over time in the DYPAI and UBAGI agars of batch 1. 


The brewing process for most beers includes heating hops and grain in nearly boiling water, before cooling the liquid down and adding a carefully selected yeast strain. Lambic sours, on the other hand, undergo a process known as spontaneous fermentation. Contrary to its name, spontaneous fermentation is a lengthy and controlled process that lasts, on average, a couple of years. The process itself depends on the strains of ‘wild’ bacteria and yeast that are already present in the environment to produce a tart flavor; normally, the presence of wild microbes causes a type of contamination referred to as ‘infection.’ ‘Infected’ beers are most easily identified by their undesirable taste, color, and smell. Therefore, as you can imagine, the microbiome of beer and how it may change during the fermentation process are of much interest to researchers and beer enthusiasts alike.

By looking at the types of microbes that colonized beer samples collected from the Belgian brewery Cantillon, prized by beer-lovers around the world, the authors of one PLOS ONE study were able to see a successive pattern in the beer’s microbiome during the fermentation process. Samples were taken from two batches that were started a month apart and cooled at different temperatures, to see how the microbial biomes varied.

The image above shows the microbial composition over time from isolates in some of the agars of batch 1. Despite some initial variety in the types of identified microbes, and a considerably high degree of species diversity overall, both batches had similar progressions in microbial content as well as a similar microbial composition at the end of fermentation; they consisted of mainly Pediococcus damnosus – a species of gram-positive bacteria that frequently grows in wine and beer. In this case, it may be that spontaneity and different starting points could all lead to a similar microbial ‘colony.’


Brews Gone Wild


Figure 2 of the published article shows some of the species found in the different batches of ACA over a three year period. Panel A shows the yeast, Panel B is the bacteria, and Panel C shows the lactic acid bacteria.


The American coolship ale is a type of beer that also utilizes the power of wild yeast and spontaneous fermentation, and is modeled after the above-mentioned Lambic style. In a 2010 PLOS ONE study, researchers investigated the microbial profiles of multiple batches of American coolship ale from a single brewer in the Northeastern United States, to see if they could establish a “microbial baseline” for this type of beer. The authors collected samples from 8 different batches throughout the 3.5- year fermentation process, and found that while the yeast and bacterial content of the beer started off with a diverse number of species, it ultimately shifted to being composed primarily of B. bruxellensis. B. bruxellensis, more commonly known as Brettanomyces bruxellensis, is the type of yeast responsible for giving beer a distinctly ‘funky,’ lightly tart flavor—it’s so distinct, in fact, that its characteristics are commonly described as ‘Bretty.’

The authors describe this particular microbial succession as likely being caused by the constantly changing environment of the beer. The strains of bacteria and yeast that initially colonized the beer produced carboxylic acid, which can limit the growth of other microbes. Once these early microbial inhabitants died off, Saccharomyces, a type of yeast commonly used in food production, and Lactobacillales were then afforded limited competition and could jump in for the main fermentation process. In the image above, the authors show how the yeast and bacterial profiles changed over time for each of the batches. They explain that since the microbial profiles and their progression are similar across all of the batches, this could be evidence that there are resident brewhouse microbiota that take over during fermentation.

It’s worth noting that studies conducted prior to this one have shown that the microbial profiles of Lambics also ultimately end up being primarily composed of B. bruxellensis, though the smaller communities of microbes differ from those found in American coolship ales.


Don’t Spoil It


Figure 4 of the published article shows how the bacterial content changed in different concentrations of various acids and maltose over time. 


While some beers, such as the previously described sours, thrive with exposure to naturally occurring microbes, others can be ruined by it. During a ‘normal’ brewing process, it is important to ensure that all equipment coming in contact with the beer has been sterilized so that contamination or infection can be avoided. The lactic acid bacteria that helps sours achieve qualities such as their distinctive aroma, may cause other beers to spoil. Luckily, drinking a spoiled beer does not put you at a huge risk for getting sick; they are generally just unpleasant tasting and not very drinkable. Many types of bacteria are unable to grow amid hops, ethanol, and a highly acidic environment; however, a few species have grown to overcome these obstacles.

To better understand the mechanisms employed by these bacteria, researchers of this PLOS ONE study conducted a type of next-generation sequencing called transcriptome sequencing on one of the culprits of beer spoilage: a strain of Gram-positive bacteria called Pediococcus claussenii. The above image shows how the bacterial levels changed over time in relation to the concentrations of various acids present in the beer. Using transcriptome sequencing allowed these authors to determine which genes are used by bacteria when they grow in acidic, low-nutrient environments. While many of these mechanisms are still not well understood, the authors identified genes that may play a key role in the bacteria’s adapted ability to live in these conditions, such as a modification of the cell membrane to resist the acidic environment. Developing a better understanding of how these bacteria are able to live in beer may help avoid contamination in the future.


While beer is enjoyed by many, most don’t give much thought to the science behind the craft. As indicated here, even spontaneous fermentation is a carefully conducted and complicated process that has evolved greatly over the last 7,000 years.

There is a special place where scientist and beer lover unite, as shown by the research articles presented above, and more open access research could mean the potential for better beer, so cheers to all the beer geeks out there!



Spitaels F, Wieme AD, Janssens M, Aerts M, Daniel H-M, Van Landschoot A, et al. (2014) The Microbial Diversity of Traditional Spontaneously Fermented Lambic Beer. PLoS ONE 9(4): e95384. doi:10.1371/journal.pone.0095384

 Bokulich NA, Bamforth CW, Mills DA (2012) Brewhouse-Resident Microbiota Are Responsible for Multi-Stage Fermentation of American Coolship Ale. PLoS ONE 7(4): e35507. doi:10.1371/journal.pone.0035507

Pittet V, Phister TG, Ziola B (2013) Transcriptome Sequence and Plasmid Copy Number Analysis of the Brewery Isolate Pediococcus claussenii ATCC BAA-344Tduring Growth in Beer. PLoS ONE 8(9): e73627. doi:10.1371/journal.pone.0073627

Images: Beer Sampler by Quinn Dombrowski via Flicker, Figure 4, Figure 2, Figure 4

Commercial Funding:

Transcriptome Sequence and Plasmid Copy Number Analysis of the Brewery Isolate Pediococcus claussenii ATCC BAA-344T during Growth in Beer: This research was partly financially supported by the MillerCoors, Anheuser-Busch InBev, and Brian Williams Graduate Scholarships from the American Society of Brewing Chemists Foundation, and MillerCoors Brewing Company. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Brewhouse-Resident Microbiota Are Responsible for Multi-Stage Fermentation of American Coolship Ale: NB has received multiple scholarships donated by commercial funding sources (Briess Malt, Cargill Malt, Wine spectator; see below). All scholarships were reviewed and awarded by third-party sources (American Society of Brewing Chemists, UC Davis Department of Viticulture and Enology) and none of these companies had any contact with the authors. This does not alter the authors’ adherence to all the PLoS ONE policies on sharing data and materials.

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PLOS ONE’s Top 5 Videos of 2015 (So Far)


At the end of 2014, we highlighted some of our favorite research videos from that year. We’re only mid-way through 2015, but we already have a number of popular research videos that we’d like to share. Here are some of this year’s most popular videos of the first half of the year, all published in the Supporting Information of each research article.

To read the full research article associated with each video, click the links in the descriptions below them.

Java sparrow percussionists

Birds use vocalizations and movements to communicate with each other. In this video, the male java sparrow sings, and both birds produce bill-clicking sounds. Interestingly, the male java sparrow appears to coordinate his bill-click sounds with the notes of his song, which is similar to a human percussionist. The authors of the PLOS ONE study published in May suggest that bill-clicking sounds may be integrated with vocal courtship signals, as we see in this video, although further research is needed to understand the role bird vocalizations and movements play in courtship.


Oyster-cracking macaques

These Burmese long-tailed macaques use stones as tools to crack open oysters. The authors of this PLOS ONE study published in May found that 80% of a population of Burmese long-tailed macaques on an island in southern Thailand use stone and shell tools to crack open seafood. The video shows that there’s more than one way to crack an oyster – in fact, there are 17 different ways!


Not-so-silent cicadas

This insect species Karenia caelatata is called the “mute” cicada since it lacks the usual organs required to produce sounds. However, the authors of this PLOS ONE study published in February describe a new sound-production mechanism for these cicadas: banging the forewing costa, or front wings, against the operculum, or body cavity, to create impact sounds, which you can hear in this video.


Escaping the jaws of death

Trap-jaw ants have large mandibles, or insect mouth parts, that they use to consume prey. The authors of this PLOS ONE study published in May found that these mouth parts can also be used to escape from an antlion predator. This video depicts an ant using its mandible to jump away and escape from the antlion buried in the sand. The trap-jaw ant snaps its mandible against the wall of the pit, and the strength of the force propels it out of the pit and out of danger.


Joint-cracking MRI

Our most popular video from 2015 is a real-time MRI (magnetic resonance imaging) of joint cracking in a human, with over 500,000 views! For more than a half century, cracking sounds from human synovial joints, or the most common and movable type of joint, were attributed to bubbles collapsing within the joint. The authors of this PLOS ONE study published in April found evidence from MRI that joint cracking is related to the formation of cavities, rather than the sudden collapse of a cavitation bubble as was previously thought. Further research is needed on how joint cracking may impact health outcomes.

We hope you enjoyed watching some of this year’s most popular research videos, and we encourage you to check out more of our videos on the PLOS Media YouTube channel here! Feel free to subscribe to stay up-to-date on all of our latest Open Access research videos.


Image and Video 1: Soma M, Mori C (2015) The Songbird as a Percussionist: Syntactic Rules for Non-Vocal Sound and Song Production in Java Sparrows. PLoS ONE 10(5): e0124876. doi:10.1371/journal.pone.0124876

Video 2: Tan A, Tan SH, Vyas D, Malaivijitnond S, Gumert MD (2015) There Is More than One Way to Crack an Oyster: Identifying Variation in Burmese Long-Tailed Macaque (Macaca fascicularis aurea) Stone-Tool Use. PLoS ONE 10(5): e0124733. doi:10.1371/journal.pone.0124733

Video 3: Luo C, Wei C, Nansen C (2015) How Do “Mute” Cicadas Produce Their Calling Songs?. PLoS ONE 10(2): e0118554. doi:10.1371/journal.pone.0118554

Video 4: Larabee FJ, Suarez AV (2015) Mandible-Powered Escape Jumps in Trap-Jaw Ants Increase Survival Rates during Predator-Prey Encounters. PLoS ONE 10(5): e0124871. doi:10.1371/journal.pone.0124871

Video 5: Kawchuk GN, Fryer J, Jaremko JL, Zeng H, Rowe L, Thompson R (2015) Real-Time Visualization of Joint Cavitation. PLoS ONE 10(4): e0119470. doi:10.1371/journal.pone.0119470

All videos are published under a Creative Commons Attribution license, and may be freely reused and remixed.

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PLOS Recommended Data Repositories

In line with our updated Data Policy, we are pleased to announce a PLOS Data Repository Recommendation Guide.

To support the selection of data repositories for authors, PLOS has identified a set of established repositories, which are recognized and trusted within their respective communities. To develop the list, we consulted with editors, organizations running data repositories, and other publishers in order to cover the breadth of disciplines and subject areas published by PLOS.

Additionally, the Registry of Research Data Repositories (Re3Data) is a full scale resource of registered repositories across subject areas. Researchers can browse by subject, content type, and country.  Re3Data provides detailed information on an array of criteria to help researchers identify the most suitable repository for their needs (licensing, certificates & standards, policy, etc.).

Authors are encouraged to select the repository most appropriate for their research. PLOS does not dictate repository selection for compliance with our open data policy, we just require the underlying data to be publicly available in a repository with licensing policies not more restrictive than the Creative Commons Attribution (CC BY) license that each paper is published under.

We appreciate your support of the policy and we welcome questions and feedback at data[at]plos[dot]org.

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I Know What You Think: Collective Intelligence in Online Communication

Have you ever wondered what factors may shape the interactions we have in online chatrooms? With the advent of the Internet 20+ years ago, the ways in which we communicate have drastically changed, allowing us to easily interact nonverbally or anonymously. Whether it’s in a chatroom, email thread, or an online forum, most of us have taken part in some form of group communication on the Internet. Maybe, unbeknownst to us, we became a part of the group’s collective intelligence, a form of group intelligence that can surface after collaboration and competition among individuals in the group. But some scientists are wondering, how can we measure the ability of others to communicate in a group, and how can we quantify the effectiveness of a group?

Two traits that make us “distinctly human” are our abilities to empathize and to interact well in social settings with others. These traits are usually measured in face-to-face situations, and may be more difficult to measure online, away from in-person social cues.

One factor that correlates to overall collective intelligence is “Theory of Mind” (ToM), or the ability of one individual to understand the mental state of another and recognize it as distinct from their own; what some may consider “mind reading.” In a recent PLOS ONE study, MIT researchers tested the hypothesis that ToM, which can be used to predict collective intelligence in collaborative face-to-face tasks, can almost equally predict collective intelligence in online collaboration. One individual’s ability to “read” the behavior of another individual can help contribute to successful communication and overall group intelligence. More than that, this ToM ability may exist even where verbal communication is prohibited, and may contribute to successful communication within an online group.

The researchers in this study recruited around 270 individuals to participate in a series of tasks online or in person. For individual tests, the participants completed the Reading the Mind in the Eyes (RME) exercise, which requires an individual to estimate the mental state of a face based on an image they are given. This test was performed in addition to several online tasks, some group-based, and some individual.

Figure 1

The researchers structured the online tasks similarly to previous in-person studies of collective intelligence. The group tasks for the individuals online included solving a Sudoku puzzle using a group chat function (see image above), unscrambling words, performing memory tasks, or typing large text pieces with the help of the group. The individual personalities of each participant were also used to contextualize their unique place in the group dynamic.

This group data, in combination with individual RME results, provided a statistical factor that was used to measure the “general intelligence” among the online group. The amount of communication, and the ToM abilities of the group, were strongly correlated with high collective intelligence.  More importantly, the medium of communication (online) did not hinder any abilities to contribute to group tasks or to interpret the emotions of others.

In an age where we rely on the Internet for rapid communication, it can be comforting to know that our collective intelligence may not diminish. These interactions could be as productive and as stimulating as many of the group conversations we have on the phone or in person. The ability to communicate and perceive group dynamics may transcend the limitations of the Internet and allow us to continue to understand and collaborate well with our fellow human.

Citation: Engel D, Woolley AW, Jing LX, Chabris CF, Malone TW (2014) Reading the Mind in the Eyes or Reading between the Lines? Theory of Mind Predicts Collective Intelligence Equally Well Online and Face-To-Face. PLoS ONE 9(12): e115212. doi:10.1371/journal.pone.0115212

Image 1: Official GDC by Jesse Knish Photography

Image 2: Figure 1 from the article

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Flight of the Bats: Exploring Head Shape and Aerodynamics


It’s a bird…it’s a plane…it’s a bat! All three may be soaring through the sky, but their shapes vary greatly, which affects their aerodynamics during flight. Birds typically have streamlined head profiles that strongly contrast with the appendages featured on echolocating bats. For example, birds do not rely as bats do on external pinnae, the visible part of the ear outside the head, to localize sound during echolocation, or the use of sound waves to locate objects in space. Some bat species also have a large noseleaf, or nose ornament, which allows them to vocalize through their nostrils and direct the echolocation call. While pinnae and noseleaves allow a bat to perform echolocation for hunting and foraging, they are often large in comparison to the bat’s body, and this could potentially slow the bats down by creating a large amount of drag, or resistance, as the bat flies.

To better understand how the structure of a bat’s head might affect its ability to fly, the authors of this PLOS ONE study tested seven different bat species with varying head shapes, including a bat species with a noseleaf, an appendage which hadn’t been tested previously.


The researchers conducted micro-computerized tomography scans (CT scans) on previously deceased bat heads collected from labs, and then 3D-printed models of the heads. They then created a standardized bat body profile for these models based off of photos of different species of bats in flight, such as the pale spear-nosed bat and the hairy big-eared bat flight poses shown in B and C in the image above. As there were no high-quality flight images available for the common big-eared bat, the authors used images of the hairy big-eared bat, a close relative, to approximate its head posture.

Each of the bat models were placed in a wind tunnel for aerodynamics testing. The models were tested at angles of attack, or the angles a bat flies toward its prey, between −30° and +30°, at air speeds of 5 m/s and 10 m/s, to measure factors such as drag and lift. The graphs below show that while the bat heads generate a large amount of both lift and drag, the lift-to-drag ratio is high for all bat species. This means that the bats experience slightly more lift than drag, and since an increased lift-to-drag ratio helps aid in flight, the authors suggest that the bats’ head shapes may not be hindering their flight as much as previously thought.


The authors conducted additional testing with the long-legged bat model, to determine whether a bat possessing both pinnae and a noseleaf would also experience more lift than drag in the wind tunnel.  The graphs below show that the bat model with pinnae and noseleaf attached experiences high lift and drag, and when these are removed, those forces mostly decrease.


Since the bat pinnae generate more lift than drag in most cases, the authors suggest that the shape and features on the bats’ heads do not produce a heavy aerodynamic cost, but may actually aid their flight.

While these researchers aren’t the first to suggest that pinnae may also create lift, they expand on this result with more detailed models of a range of bat species, with different pinnae lengths, and by including a species that has a noseleaf. Furthermore, since the researchers tested bat species from a wide variety of ecological niches, or the ways in which the bats function within the ecosystem, their findings may be more easily generalized across the bat taxa than previous research.

While the authors acknowledge that there are limitations to testing static models for bat aerodynamics, their results suggest that pinnae and noseleaves may not affect bat aerodynamic capability as was previously thought. Looks like the shape of the bats’ faces might not slow down their nighttime flight after all!

Citation: Vanderelst D, Peremans H, Razak NA, Verstraelen E, Dimitriadis G (2015) The Aerodynamic Cost of Head Morphology in Bats: Maybe Not as Bad as It Seems. PLoS ONE 10(3): e0118545. doi:10.1371/journal.pone.0118545

Gardiner J, Dimitriadis G, Sellers W, Codd J (2009) The aerodynamics of big ears in the brown long eared bat plecotus auritus. Acta Chiropterologica 10: 313–321. doi: 10.3161/150811008X414881

Images: Image 1: Bernard Dupont on Flickr, Images 2, 3 and 4: Figures 1, 2 and 4 from published article.

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