A Blog by

231 Varieties of Rain: Frogdrops Keep Falling on My Head

Poor Rob McKenna. He drives a truck, so he’s constantly moving, never in the same place for long. And yet everywhere he goes—city, country, near, far, morning, afternoon—it doesn’t matter, wherever Rob is, it’s raining. He can turn, reverse, zigzag, it doesn’t matter. Clouds just follow him, and to prove it (because who would believe this?) he keeps a log and shares it with his friend Arthur Dent, who says, You should show this to scientists. He does, and the scientists tell him, Rob McKenna, we know what you are. You are a Quasi Supernormal Incremental Precipitation Inducer.

What’s that?

He’s a “Rain God.” That’s the gist. Clouds see him and can’t help themselves. They love him and want “to be near him, to cherish him, and to water him.” And the worst of it is, Rob (a totally fictional character in Douglas Adams’s Hitchhiker’s Guide to the Galaxy) hates rain. Can’t abide it. But the rain doesn’t care. So Rob tries to get along. He turns his curse into a part time job: Hotels and vacation spots pay him not to go there. He becomes a regular at a pub called the Thundercloud Corner, where he sits, grimly staring out the window at … well … at scenes like this:

GIF by tkyle
GIF by “tkyle

But because he spends so much time staring at rain, Rob learns to see rainfall as no one has seen it before; he sees its many shapes, moods. He realizes, in the words of poet Conrad Aiken, that raindrops are “the syllables of water,” that rain can take hundreds of different forms.

There’s lashing rain, sheets of rain, rain pissing, bucketing, pouring. There are drizzles. There are mizzles. But Rob McKenna likes superspecific categories. He’s a taxonomist. And so he creates his own rain glossary; it’s described in So Long, and Thanks for All the Fish—the fourth book in the Hitchhiker’s Guide series—with its 231 different rain types:

There’s “light pricking drizzle which made the roads slippery” (type 33).

There’s “vertical light drizzle” (type 47).

There’s “heavy spotting” (type 39) .

There’s “regular” cab-drumming and “syncopated cab-drumming” (types 126 and 127).

There’s “dirty blatter blattering against his windscreen so hard that it didn’t make much odds whether he had his wipers on or off” (type 17).

I love parsing through Rob’s categories. Being a rain gazer myself (and rain, by the way, feels especially noticeable here in New York, where I live) …

The wonderful graphic designer T. Kyle MacMahon—known as “tkyle”—is especially good at capturing the joys of rain-gazing.
The wonderful graphic designer T. Kyle MacMahon—known as “tkyle”—is especially good at capturing the joys of rain-gazing.
GIF by tkyle


GIF by tkyle
GIF by “tkyle

… I couldn’t help but notice that something is missing from Rob’s list. He limits himself to one kind of rain—the kind that rains water, what you might call “raindrop rains.” But, in fact, there are other kinds.

In her book Rain: A Natural and Cultural History, Cynthia Barnett mentions Jonathan Swift’s fanciful metaphor “raining cats and dogs” (a coinage from 1738), but she then goes on to describe actual, unfanciful, documented rains of—and I kid you not—golf balls, fish, and, though I’ve heard about this before, frogs. As in, raining frogs (or toads).
Frog rain is shockingly normal.

Drip, Drop, Thunk

Barnett writes that in June 1954, Sylvia Mowday and her kids were in a park in Sutton Coldfield, just north of Birmingham, England, when it began to rain. They opened their umbrellas and were heading for shelter when all of a sudden they felt “gentle thuds” on their umbrella tops, “too soft for hail.” When they looked, they saw tiny frogs, “wee bodies” falling from the sky.

Maybe that’s what you’re seeing in this video—posted from Knox County, Ohio, on June 11, 2012—which shows (after the filmmaker, “MrKoozzz,” focuses) teeny frogs, all facing the same way, after a rain. (Alternate explanation: Could they be migrating? Hopping from one pond to another? Nope, they arrived by rain, writes MrKoozzz. “That’s my story, and I’m sticking to it.”)

In 1873, Scientific American ran eyewitness accounts of a frog rain in Kansas City, Missouri. It happened again, Barnett writes, in 1901, in Minnesota. There are ancient accounts, medieval accounts, even battlefield stories. During a French/Austrian battle in 1794 …

“A hot afternoon was broken by such heavy showers that 150 soldiers had to abandon their trench as it filled with rainwater. In the middle of the storm, tiny toads began to pelt down and jump in all directions. When the rain let up, the soldiers discovered more toads in the folds of their three-cornered hats.”

Drawing by Robert Krulwich
Drawing by Robert Krulwich

Assuming that all these stories—or at least some of them—are true, how do hundreds of toads manage to get airborne? Little toads—teeny as they are, are much heavier than raindrops. “Modern meteorologists,” Barnett explains, believe that “tornadoes and waterspouts are the most likely culprits.” High winds, especially whirlwinds, pick up water, toads, frogs (fish, golf balls) and all, and whisk them across the sky for a little while, then lose speed and dump the contents on, for example, Sylvia Mowday and her kids.

(Though, Cynthia wonders, if a whirlwind can pull a frog up into the sky, where’s the algae, the other pond plants, the fish? Why didn’t the Mowdays get hit with pond scum? She doesn’t know.)

But frog rain happens. Maybe not as often as rain type 49 (“sharply slanting light drizzle”) or type 51 (“light to moderate drizzle freshening”) or a “dirty blatter battering,” but frogs have been falling from the skies often enough, long enough, that I think they’ve earned the right to be called precipitation.

It’s odd that Rain God Rob MacKenna would leave them out. But he’s a lesser deity. The Big Guy, as you may recall, was more frog-friendly. Just ask Pharaoh …

For the best, craziest, most over-the-top frog rain ever (particularly the slack-jawed look on Philip Seymour Hoffman’s startled face when giant toads begin falling from the sky into his brilliantly lit swimming pool), there is nothing better than Paul Thomas Anderson’s 1999 movie Magnolia. If you dare (and I suggest you do … but it’s pretty graphic …) take a look …

A Blog by

This Frog Uses Its Spiky Face to Deliver a Venomous Headbutt

When Carlos Jared was first ‘stung’ by the venomous face of the Greening’s frog, he didn’t realise what had happened. He had picked up one of the small creatures, and it started thrashing about as if trying to headbutt his hand. At first, it felt like being abraded by rough sandpaper. Then, Jared quickly developed an intense pain, which radiated up his arm and lasted for five hours. And since he was four hours away from any major city, he just had to grin and bear it.

Jared didn’t initially connect the pain to the little frog he had picked up. After all, there was no obvious injury. Only later did he figure out what had happened: The frog had released toxins from its skin, and used the small spines that line its skull to drive those poisons into his hand. He had received a venomous headbutt.

Greening’s frog, also known as the casque-headed tree frog, was first described in 1896. It’s a palm-sized animal with mossy green skin and a distinctive flattened head. The many bones of the top of its skull have fused together, and merged with the lower layers of skin to create a single, sturdy plate.

Partly, this is an adaptation against dehydration. Greening’s frogs (like all of them) depend on water, but they also live in the extremely dry Caatinga forests of Brazil. Their solution is to shuffle backwards into holes and then plug the entrance with their bony helmets. That seals their bodies in humid spaces and stops them from losing too much water.

Since the skull is both flat and well camouflaged, it’s very hard for predators to spot the frogs, let alone pull them out of their hollows. And if any predators are tempted to try, the lip region of the skull is covered in wicked-looking spines. With all the flesh removed, the skull looks a bit like a medieval mace.

The skull of Greening's frog. Credit: Carlos Jared/Butantan Institute
The skull of Greening’s frog. Credit: Carlos Jared/Butantan Institute

Jared experienced firsthand what these spines can do when he started collecting the frogs in Caatinga. He was lucky to only get hours of pain. He soon discovered that the frogs can release a white, toxic mucus from glands in their skin, which can be lethal when swallowed. These glands are especially large in the frog’s face, where they sit over the skull spines. So, when threatened, the frogs can slather their own face with toxic mucus, and then drive it into an antagonist’s flesh using their own skull—a tactic that’s aided by their unusually flexible necks.

So are these frogs poisonous or venomous? Poisonous animals have no way of injecting their toxins, although they might be able to secrete them. That’s the case for most toxic amphibians. “They have a passive defense, only offering their own bodies (or parts of them) to be bitten by the predator or aggressor,” says Jared. “The predator is responsible  for its own poisoning.” By contrast, venomous animals can actively deliver their toxins into an enemy or victim using stings, spurs, or fangs. That’s the case for spiders, snakes, and scorpions.

The casque-headed frogs clearly fit in both categories. They can release toxins through their skin—a passive defence. They can also introduce those toxins directly into wounds using their spines—an active defence. Regardless of semantics, what matters is that the defence works.

When tested on mice, the toxins from Greening’s frog proved to be twice as lethal as those of the notorious fer-de-lance snake, and other pit vipers that share the same forests. A second closely related frog—Bruno’s casque-headed frog—is even more dangerous. Its poison glands are smaller and its skull spines are shorter, but its toxins are 25 times more lethal than pit viper venom.

Bruno's casque-headed frog Credit: Carlos Jared/Butantan Institute
Bruno’s casque-headed frog. Credit: Carlos Jared/Butantan Institute

“During all these years that I’ve lived with these animals in their environment, I’ve never seen any sign of predation, or aggression by predators,” says Jared. He imagines that for a snake, swallowing these frogs would be like trying to wolf down a poisoned cactus.

Reference: Jared, Mailho-Fontana, Antoniazzi, Mendes, Barbaro, Rodrigues & Brodie. 2015. Venomous Frogs Use Heads as Weapons. Current Biology http://dx.doi.org/10.1016/j.cub.2015.06.061

See also: ‘Wolverine’ frogs pop retractable claws from their toes


Paleontologists Uncover “Super Salamander” Boneyard

Finding fossils takes a combination of skill and luck. You have to be looking in the right place and have some idea of how to distinguish those precious pieces of prehistoric life from all the rock surrounding it. But that’s not all. How the sun hits stone, where your eyes fall along the outcrop, and even where you stop to take a leak can make all the difference between finding something amazing and passing it by. And that’s just in the field. Museum collections hold petrified trails of bread crumbs, too, leading to forgotten places whose fossiliferous potential hasn’t been realized.

Sometime in the late 70s or early 80s, geology student Thomas Schröter was hiking through the red rocks of Algarve, Portugal when he spotted some fossil bone. They didn’t relate to the thesis he was working on, but he picked them up anyway. While not especially remarkable, the scraps nevertheless made the customary transition from field to museum collection and were later appraised as those of a metoposaur – salamander-like amphibians that could get up to 10 feet long and lived a lifestyle one of my professors once called “crocodiling before there were crocodiles.”

These enormous amphibians were, and are, anything but rare. They’re among the most common fossils found in the 237-201 million year old rock representing Late Triassic time, sometimes clustered together in dense bonebed where they died en masse. And as paleontologists Stephen Brusatte, Richard Butler, Octávio Mateus, and Sébastien Steyer found when they relocated the Algarve site in 2009 after reading a short description of the fragments plucked from the site, Schröter had discovered another such graveyard.

Paleontologists excavate the Algarve bonebed in Portugal. Photo courtesy Stephen Brusatte.
Paleontologists excavate the Algarve bonebed in Portugal. Photo courtesy Stephen Brusatte.

There’s more in the Algarve bonebed than has yet been excavated and prepared. So far, however, Brusatte and colleagues have uncovered multiple skulls and bones from the chests of these aquatic ambush predators. And while these remains are similar to those of other Metoposaurus found elsewhere in Europe, they’re different enough to justify establishing a new species – Metoposaurus algarvensis.

What brought so many Metoposaurus together to die isn’t clear. At this point, the researchers write, it’s unknown whether they died in the place they were entombed or their remains were washed in from elsewhere. But seasonal droughts could have played a role.

Metoposaur sites around the Triassic world. From Brusatte et al., 2015.
Metoposaur sites around the Triassic world. From Brusatte et al., 2015.

Algarve was much closer to the equator in the Triassic than today, scorched in dry seasons and doused by the return of the monsoons. Perhaps the unfortunate Metoposaurus were pushed together into an ever-shrinking water source, baked to death before rains returned to bury them.

Regardless of the reason for their death, though, the fossils are part of a metoposaur band that ran across the middle of Pangaea, the only outliers being a cluster in prehistoric India and Madagascar. Future finds will alter this picture to greater or lesser degrees, but it may be that metoposaurs thrived in hot, highly-seasonal environments where early dinosaurs stayed small and croc cousins ruled while different predators waited along the shores of higher-latitude habitats. The only way to find out more is to keep digging.


Brusatte, S., Butler, R., Mateus, O., Steyer, S. 2015. A new species of Metoposaurus from the Late Triassic of Portugal and comments on the systematics and biogeography of metoposaurid temnospondyls. Journal of Vertebrate Paleontology. doi: 10.1080/2724634.2014.912988

A Blog by

Can Probiotic Bacteria Save An Endangered Frog?

I saw a ghost at the Vancouver Aquarium last summer. I was walking out of a room overlooking the main shark tank when I saw something in a glass cage embedded in the wall, something small, black and yellow. I mean Black and Yellow—colours so intense that you almost expect to turn the creature over and find a country of origin embossed on its underside. It was a Panamanian golden frog, and it is extinct in the wild. It only survives in zoos and aquariums. It is an ecological phantom, a ghost of nature.

Several factors took the frog to the edge of oblivion but the one that landed the most punishing blows was a chytrid fungus called Batrachochytrium dendrobatidis, or Bd for short. It is the same grim antagonist that has severely reaped the populations of some 200 amphibians and seems to be working its way through the rest. It is catholic in its choice of hosts and apocalyptic in its effects. The Panamanian golden frog is just one of its victims.

Conservationists have been incredibly successful at breeding the frog in captivity. But if they release these animals back into their native habitat, where Bd still persists, who’s to say they wouldn’t just die? Their ark is full, but there’s no Mount Ararat in sight.

In 2006, a team of researchers stumbled across a possible solution. They found that a few amphibians, including two salamanders and the mountain yellow-legged frogs, naturally carry a bacterium called Janthinobacterium lividum that stopped Bd from growing. It was an anti-Bd probiotic, a microbial shield that turned frogs into resistant fungus-fighters. And when the team applied the bacterium to yellow-legged frogs that didn’t already have it, those individuals also became resistant.

Could J.lividum protect other frogs too? To find out, Matthew Becker from James Madison University, who was part of the original team, teamed up with Brian Gratwicke from the Smithsonian Conservation Biology Institute, who had a group of lab-bred golden frogs. They soaked the frogs in a J.lividum bath and challenged them with Bd. If the approach worked and the frogs survived, perhaps they could be released into the wild, cloaked in their living armour.

It didn’t work. The probiotic microbe didn’t persist on the frogs’ skins, and it did nothing to save them from the fungus. “We thought maybe it wasn’t a good fit,” says Becker. “This bacterium was from California and these frogs are from Panama.” Perhaps frogs from different parts of their carry their own particular probiotic microbes that have adapted to thrive on their skins. If Becker was going to find a probiotic that could protect the golden frogs, he would need to go to Panama.

He went in 2011 and spent a week surveying the skin bacteria of local frogs, focusing on species that were as closely related to the golden frog as possible. Over a week, he collected 450 samples and found several microbes that stopped Bd from growing, at least in lab tests. He focused on four of these, and applied them to captive golden frogs, to see whether they could then survive a bout with Bd.

They couldn’t. On average, the treated frogs survived no longer than untreated ones. And once again, “nothing persisted,” says Becker. “Their existing microbial community didn’t even shift in response to [the new microbes].”

The same problem plagues human probiotics. When they’re swallowed, they don’t take up permanent residence in the gut and they don’t affect the make-up of the local bacteria communities (although they do seem to change the activity of certain genes). After all, a typical yoghurt contains several billion bacteria, whereas our gut contains tens of trillions. It’s like a raindrop falling into a lake. Perhaps this explains why probiotics can help with a small number of diseases, like diarrhoea caused by infections, but have largely failed to live up to the hype that surrounds them.

With the frogs, Becker wonders if he applied too many microbes rather than too few. “I think we may have activated the frogs’ immune systems and prevented the probiotics from establishing,” he says. Alternatively, we know that even closely related animal species can host distinctive microbiomes, so what persists on one frog may just not thrive on another. It’s also possible that the skins of captive golden frogs are already colonised by microbes that stop the bacteria of their former Panamanian neighbours from colonising.

In the midst of their disappointment, the team found a silver lining. Five of the frogs managed to clear the fungus on their own. “That’s pretty unheard of in golden frogs,” says Becker. When he focused on these animals, he found that they differed from those that died, in the groups of bacteria on their skin and the chemicals that those bacteria produced.

What are these microbes? Do they actually protect against Bd or are they indicators of some inherent resistance, perhaps some immune genes that both resist the fungus and select for specific skin microbes? If they do protect against Bd, would they do so in the wild? Are they part of a golden frog’s natural repertoire, or did they only start colonising these animals in captivity? The team is now working to answer these questions. Becker is sampling 200 of golden frogs at Maryland Zoo in Baltimore to see if he can find these potentially protective communities, and then apply them to other frogs to see if they also become Bd-resistant.

The concept of using probiotics to protect amphibians (and perhaps other animals at risk from widespread epidemics, like bats) makes sense. Many animals, from humans to corals, carry skin microbes that protect us from incursions by disease-causing species, by secreting natural antibiotics, mobilising our immune systems, and simply filling up niches that the invaders might otherwise exploit.

But our own experience with probiotics, and Becker’s frog experiments, tell us that deploying these seemingly beneficial bacteria is easier said (and marketed) than done. Probiotics may help to save the frogs but it’s unlikely that we’ll see a one-size-fits-all solution, and the same could be said for the use of microbes in human medicine.


There will be more about frogs and conservation probiotics in my book, I Contain Multitudes, out next year.

Reference: Becker, Walke, Cikanek, Savage, Mattheus, Santiago, Minibiole, Harris, Belden & Gratwicke. 2015. Composition of symbiotic bacteria predicts survival in Panamanian golden frogs infected with a lethal fungus. Proc Roy Soc B http://dx.doi.org/10.1098/rspb.2014.2881

More on Bd:

Update: The post originally said that the 200 golden frogs that will feature in upcoming experiments were at the Smithsonian; they actually live at Maryland Zoo in Baltimore.

New Frog Species Reproduces Like No Other

There’s not really a good time to bring up amphibian mating habits at the dinner table. I figured that I was probably safe given that I was surrounded by scientists, but, all the same, I tried to make sure that no one was raising a fork to their mouths when I blurted out “You guys! There are frogs that have sex!”

The inspiration for my outburst came from a PLOS One paper published just before I headed out the door for New Year’s Eve dinner. In it, biologists Djoko Iskandar, Ben Evans, and Jimmy McGuire describe a frog that reproduces unlike any other known species.

Most frogs and toads look like they’re having sex when they’re mating, but this is a superficial illusion. It’s a behavior called amplexus in which the male amphibian clasps the female around the torso, shoulders, or head and releases his sperm as she lays her eggs.

The new frog species – named Limnonectes larvaepartus – is one of the rare exceptions. Like a handful of other frogs and toads, this newly-described amphibian from Sulawesi Island is capable of internal fertilization. The way the frogs accomplish this is a mystery – the Limnonectes larvaepartus males appear to lack what science has politely called an “intromittent organ” – but what happens next is a sure sign that the fanged frogs don’t spawn like other species.

All other frogs and toad species that have sex deliver their young in one of two ways. The females either lay their internally-fertilized eggs in typical amphibian fashion or the mothers give birth to well-developed froglets. Limnonectes larvaepartus splits the difference. Females of the new species, Iskandar and colleagues report, gives live birth to tadpoles.

The researchers first discovered this unusual ability while prepping collected frogs. When they dissected some of the females, “the abdominal wall was observed to quiver, and incision resulted in living tadpoles emerging from the opening.” Live frogs later gave birth to squiggly tadpoles at the time of collection and while being held for study.

An adult Limnonectes larvaepartus with tadpoles in a pool (yellow circle) and a close-up of the tadpoles. From Iskandar et al., 2014.
An adult Limnonectes larvaepartus with tadpoles in a pool (yellow circle) and a close-up of the tadpoles. From Iskandar et al., 2014.

While there’s a possibility that the fanged frogs may have been capable of retaining those tadpoles until they fully metamorphosed into froglets, Iskandar and coauthors consider this unlikely. All 19 pregnant females collected for the study had tadpoles inside, not froglets, and the researchers also found free-living tadpoles in streamside pools. Once released into the outside world, the developing frogs live off what little yolk they have left before starting to feed for themselves. And given that this news was received positively as dinner concluded, I can heartily recommend that you share the tale of this remarkable frog the next time you meet friends for a meal. I’m sure they’ll find it ribbiting.


Iskandar, D., Evans, B., McGuire, J. 2014. A novel reproductive mode in frogs: A new species of fanged frog with internal fertilization and birth of tadpoles. PLOS One. 9 (12): e115884. doi:10.1371/journal.pone.0115884


In the annals of paleontology, Snowmastodon holds a very special place. The site isn’t only remarkable for what was discovered there – a dense Ice Age boneyard containing at least 35 mastodons, four mammoths, and numerous other fossils – but the fact that paleontologists and volunteers carefully excavated and documented the fossils in less than nine months. It’s a great example of uncovering prehistory under pressure, and those hectic excavations of 2010-2011 are already starting to bear scientific fruit.

Thanks to a list of interdisciplinary researchers too long to name individually (just have a look at the author lists!), the journal Quaternary Research has devoted an entire issue to the Snowmastodon site. This is just the first rush of papers, but they set the foundation for understanding what the high-altitude habitat was like between 140,000 and 77,000 years ago.

Despite falling within the “Ice Age”, for example, the earliest sediments from the site actually document a relatively warm, wet habitat where American mastodon and Jefferson’s giant ground sloths browsed among conifer forests that bordered a broad lake. In time, the climate became cooler and drier. The forests began to die back and the lake was filled in to form a marshy meadow closer to 77,000 years ago, and this is when “Snowy” the mammoth and deer moved in.

But even though Snowmastodon was named for a classic and charismatic megamammal the American mastodon wasn’t the most numerous vertebrate at the site. Not even close.

Snowmastodon at the time of the mastodons (top) and mammoths (bottom). Tiger salamanders thrived through these changes. From Miller et al., 2014.
Snowmastodon at the time of the mastodons (top) and mammoths (bottom). Tiger salamanders thrived through these changes. From Miller et al., 2014.

After sorting through all the recovered remains, the Snowmastodon researchers documented a minimum number of 35 mastodons and over 1,800 individual mastodon bones in sediments from 140,000 to 110,000 years old. Compare that to the haul of tiger salamanders. Their bones were typically too small to see out in the field, but, in doing preparation on the big bones and sifting sediment, the Snowmastodon team has documented over 22,000 bones from tiger salamanders that represent at least 500 individuals which lived during the entire 140,000 to 77,000 year range.

I get marketing and I like puns. The site was rich with mastodons and uncovered near Colorado’s Snowmass Village, so Snowmastodon was the obvious choice for a popular name. But if sheer numbers were to dictate the name, Snowsalamander would be the clear winner.

Of course, tiger salamanders are not nearly as exciting as big shaggy mammals that disappeared practically yesterday. It’s a hard break for the herps. Then again, they are among the species preserved at Snowmastodon that survived to the present.

The tiger salamanders of Ice Age Colorado were the same species as those alive today. They thrived at the site’s lake and marshland, and bones from every stage of their development show that the salamanders lived at Snowmastodon for generation after generation. One tiger salamander skeleton was even found inside a mastodon’s tusk, buried as it sheltered inside the modified incisor. This makes the tiger salamander yet another connection to the not-too-distant past, and every time I see one I can’t help but think of the little amphibian clambering over the fresh, submerged bones of a mastodon in those Ice Age days.

To learn more about Snowmastodon, read the new Quaternary Research issue devoted to the bonebed.


Fisher, D., Cherney, M., Newton, C., Rountrey, A., Calamari, Z., Stucky, R., Lucking, C., Petrie, L. 2014. Taxonomic overview and tusk growth analyses of Ziegler Reservoir proboscideans. Quaternary Research. 82: 518-532. doi: 10.1016/j.yqres.2014.07.010

Miller, I., Pigati, J., Anderson, R., Johnson, K., Mahan, S., Ager, T., Baker, R., Blaauw, M., Bright, J., Brown, P., Bryant, B., Calamari, Z., Carrara, P., Cherney, M., Demboski, J., Elias, S., Fisher, D., Gray, H., Haskett, D., Honke, J., Jackson, S., Jimenez-Morena, G., Kline, D., Leonard, E., Lifton, N., Lucking, C., McDonald, H., Miller, D., Muhs, D., Nash, S., Newton, C., Paces, J., Petrie, L., Plummer, M., Porinchu, D., Rountrey, A., Scott, E. Sertich, J., Sharpe, S., Skipp, G., Strickland, L., Stucky, R., Thompson, R. Wilson, J. 2014. Summary of the Snowmastodon Special Volume: A high-elevant, multi-proxy biotic and environmental record of MIS 6-4 from the Ziegler Reservoir fossil site, Snowmass Village, Colorado, USA. Quaternary Research. 82: 618-634. doi: 10.1016/j.yqres.2014.07.004

Sertich, J., Stucky, R., McDonald, H., Newton, C., Fisher, D., Scott, E., Demboski, J., Lucking, C., McHorse, B., Davis, E. 2014. High-elevation late Pleistocene (MIS 6-5) vertebrate faunas from the Ziegler Reservoir fossil site, Snowmass Village, Colorado. Quaternary Research. 82: 504-517. doi: 10.1016/j.yqres/2014.08.002

A Blog by

Hope Against The Frogpocalypse Fungus, But Just a Sliver

Since the 1990s, the world has witnessed the rise of one of the most terrifying diseases to afflict any animal group: a doomsday fungus that is ripping through the world’s frogs and amphibians. Known as Batrachochtyrium dendrobatidis, or Bd for short, it causes a disease that has wiped out dozens of species and endangered hundreds more. It’s a global problem and earlier this year, it was finally found in Madagascar—the last Bd-free amphibian stronghold. “That’s it. The worst news imaginable,” wrote one herpetologist.

Bd news is almost always bad news. But this week, Taegan McMahon from the University of South Florida has a more positive to tell—or, at least, what passes for positive when you’re dealing with Bd. Her team showed that frogs become more and more resistant to the fungus if they are repeatedly infected and cured. They even became more resistant after the team exposed them to dead fungus.

These results offer a small sliver of hope. Perhaps conservationists might be able to vaccinate frogs against Bd using dead versions of the fungus, just as humans protect ourselves from polio or rabies. They could inoculate captive individuals before releasing them, prepared and protected, into the big, bad, Bd-filled world.

“This is the beginning to a long line of work—the first information that we need to figure out whether it’s really practical in the field,” says McMahon. “We need to test this on a larger scale, but we’re super-optimistic with it.”

Other frog specialists are more skeptical. Lee Skerratt from James Cook University in Australia praised the team’s experiments but said, “The fungus still appears to be highly virulent after four previous exposures, which fits with our current understanding. It still kills the majority of frogs after a short period of time. In comparison, inoculations with many other pathogens provide almost complete protection against future exposure.”

Karen Lips from the University of Maryland also doubts that the results will make much practical difference. “It’s already a Bd world. Essentially all amphibian species have already been exposed at some point. Many have been shown to self-clear infections, some get reinfected, some die, some don’t.” The point is that they’ve already had a chance to become resistant, only some have taken it, and we still don’t understand why.

However, she adds, “Any evidence that some amphibians are surviving with disease is good news. [And] anything that zoos and NGOs can do to promote or allow evolution of captive assurance populations would be good.”

McMahon’s team repeatedly exposed Cuban tree frogs to Bd and then raised their temperatures to clear their infections. With each passing exposure, the team found that the frogs became more and more resistant to the fungus. By the third exposure, they carried 75 percent less of it on their skins. They also mounted stronger immune responses and made more white blood cells in response to the threat. That was a surprise—Bd can suppress amphibian immune systems but it seems that, over time, the frogs can compensate.

Spraying live fungus onto frogs, especially endangered species or those only exist in captivity, would be a non-starter. So the team exposed the frogs to dead fungus to see if they could trigger the same resistance. It did, and to almost the same extent as the live fungus. “I was hopeful but not as confident that the dead fungus would work,” says McMahon. “It did, and that’s extremely exciting.”

But Lips warns that strong immune responses aren’t necessarily cause for celebration. In her own research, she found that harlequin frogs that naturally recover from a bout with Bd will die just as fast as naive frogs if re-infected, even though they mount vigorous immune responses.

In McMahon’s experiment, only 20 percent of the animals that had acquired “resistance” to the fungus were still alive after five months. They fared better than the completely naive animals, all of whom were killed, but a survival rate of 20 percent is probably not good enough to sustain a wild population. And what happens after five months? Does their shred of immunity disappear, or do the frogs lose it over time?

There are other unknowns. Bd has wildly varying effects on different frogs—harlequin frogs almost always die, but cane toads (predictably, sadly) are almost impossible to kill. It’s not clear if other frogs would react to the fungus in the same way that the Cuban tree frogs did.

Most importantly, what would happen in the wild? Lips adds that when she pits amphibians against Bd in her lab, context is everything. The same fungal strains will kill infected salamanders at 13 degrees Celsius but spare their lives at 17 degrees. “In terms of relevance for wild populations, what will happen when winter comes and temperatures drop?” she asks. Field tests are everything.

McMahon agrees. She now wants to expose frogs in mesocosms—enclosures that sit in natural settings, but that can still be carefully manipulated. That will tell her not only whether the frogs can resist the fungus outside of a lab, but also whether spraying dead fungus has any unintended consequences. After all, she previously showed that Bd can release an unknown toxin that can kill crayfish at a distance. “We want to make sure that if we’re spraying the fungus, there aren’t effects we don’t expect,” she says.

Reference: McMahon, Sears, Venesky, Bessler, Brown, Deutsch, Halstead, Lentz, Tenouri, Young, Vicitello, Ortega, Fites, Reiner, Rollins-Smith, Raffel & Rohr. 2014. Amphibians acquire resistance to live and dead

fungus overcoming fungal immunosuppression. Nature http://dx.doi.org/10.1038/nature13491

A Triassic Cuddle Set in Stone

In 1975, near the base of South Africa’s Oliviershoek Pass, paleontologist James Kitching discovered the final resting place of a small, shuffling mammal that had perished some 250 million years before. Little more than a piece of skull was poking out of the stone, but the shape and composition of the surrounding rock suggested that the poor creature had died in a burrow – and that there might be more inside. Sure enough, when Kitching cracked open the rock the little lair was pocked by even more bones, so off it went to the collection of Johannesburg’s Evolutionary Studies Institute of the University of Witwatersrand. Kitching had no idea that he had found a pair of unusual Triassic bedfellows.

The part of the fossil Kitching first spotted was a piece of Thrinaxodon. Multiple specimens of this small, squat protomammal have been found curled up inside burrows. Whether or not Thrinaxodon made their own dens is a mystery, but their remains, fossilized in repose, hint that they escaped the blistering heat of the dry season by snoozing underground.

Thrinaxodon is not alone in the Triassic tomb. Lying belly-up atop the protomammal is a rare, salamander-like amphibian named Broomistega. No one had any idea that the bonus fossil was there until University of the Witwatersrand paleontologist Vincent Fernandez and colleagues had the contents of the burrow scanned at the European Synchrotron Radiation Facility in Grenoble, France. Presented in the scan’s digital detail, published last year, the pair of fossils rest against each other in stunning articulation.

View of Thrinaxodon (A: top, B: bottom) and Broomistega (C: bottom, D: top). From Fernandez et al., 2013.
View of Thrinaxodon (A: top, B: bottom) and Broomistega (C: bottom, D: top). From Fernandez et al., 2013.

How did this Triassic mash-up come together? The fossil doesn’t offer a definite answer, but Fernandez and colleagues narrowed down the list of possibilities.

Regardless of whether the Thrinaxodon created the hollow, previous fossil finds and the anatomical improbability of a burrowing Broomistega suggest that the protomammal was the den’s primary occupant. And even though both animals were buried by a mix of water and sediment that sluiced into the burrow, it would be a hell of a coincidence if the sloshing mud carried an intact amphibian right into the burrow.

With such an accidental burial unlikely, Broomistega was either dragged in by Thrinaxodon or the amphibian purposely hauled itself into the burrow. The latter seems more likely. Even though the Broomistega bones show two possible tooth puncture marks, the size and spacing did not match the dental particulars of the Thrinaxodon. Instead, Fernandez and colleagues hypothesized, the Broomistega simply wandered into the burrow where the Thrinaxodon was sound asleep in a brief torpor, and there the amphibian lay until a mucky slurry buried them both.

Such close cohabitation is rare, even among modern animals, but the Broomistega may have had good reasons to seek shelter. For one thing, this particular animal had a series of broken, partly-healed ribs that probably hindered the amphibian’s ability to move and breathe. That’s a major problem for a creature that will quickly die if stranded in dry season sun, so perhaps the burrow was the closest place of refuge for the injured Broomistega. So long as the Thrinaxodon lay undisturbed in a multi-day slumber, as Fernandez and coauthors suspect, then the amphibian could have rested in the cool without risk of being run out by the burrow-owner’s snapping jaws. In the cool and the dark, the Triassic neighbors dozed together, died together, and became fossilized together.


Fernandez, V., Abdala, F., Carlson, K., Cook ,D., Rubidge, B., Yates, A., Tafforeau, P. 2013. Synchrotron reveals Early Triassic odd couple: Injured amphibian and aestivating therapsid share burrow. PLoS ONE 8, 6: e64978. doi:10.1371/journal.pone.0064978

Fossil “Frog From Hell” Gets a New Look

The fossil frog Beelzebufo was all mouth. Or as close to it as an amphibian can get while still making space for legs and all those other essential parts. That’s the image put forward in a new PLoS One study by University College London paleontologist Susan Evans and colleagues that has substantially revised the appearance and size of the famous fossil frog.

Evans and coauthors named Beelzebufo in 2008. Initially estimated to be about sixteen inches long and weigh about ten pounds, Beelzebufo was a contender for the largest frog of all time. But the frog’s potential diet is what really drew headlines. Pieced together from fossil fragments found in Madagascar’s 65-70 million year old rock, Beelzebufo had lived among some of the last non-avian dinosaurs. And given the frog’s size, it wasn’t a stretch to imagine the imposing anuran leaping out from the undergrowth to nab unwary baby dinosaurs.

[Beelzebufo nabs some dinosaurian dinner in this clip from Dinotasia. Jump to 4:09 for Beelzebufo.]

Based on the original description, early restorations of Beelzebufo looked like a pumped up version of the Surinam horned frog (a grouchy-looking amphibian found in South America). That made sense given the frog’s relatively close relationship to such “Pacman frogs” living today. But with recently-discovered, articulated parts of the skull, backbone, and hindlimb, Evans and colleagues have found that Beelzebufo was “even more bizarre and heavily armoured than earlier reconstructions depicted.”

The new Beelzebufo reconstruction looks like a set of legs meant to propel a huge skull.  Measuring about six inches across the back and three inches long, the frog had a short, wide head fitted with small, plate-like teeth along the jaws. With a skull like that, Beelzebufo likely ambushed and engulfed whatever prey would fit into its mouth. But, contrary to earlier estimates, the big-mouthed anuran may not have been large enough to consume infant Majungasaurus.

Top and side views of the new Beelzebufo reconstruction. From Evans et al., 2014.
Top and side views of the new Beelzebufo reconstruction. From Evans et al., 2014.

Using measurements from the Brazilian horned frog to plug some skeletal gaps, Evans and coauthors estimate that the most complete Beelzebufo yet found was only about seven and a half inches long. There’s scrappy evidence for bigger Beelzebufo that may have been about nine inches long, and different individuals likely reached disparate adult sizes, but the frog wasn’t so monstrous as the globular, dinosaur-chomping glutton that made headlines six years ago.

Nevertheless, the new, more complete fossil material has allowed Evans and colleagues to gain a better understanding of how Beezlebufo survived in Cretaceous Madagascar. The frog was too heavily-built to hop, and instead walked over a landscape that experienced harsh swings between the wet and dry seasons. And given similarities between Beelzebufo and its living relatives in South America, Evans and coauthors propose that the fossil frog likely burrowed into the soil to escape the heat.

Beelzebufo may have spent the hottest, driest periods fully or partially buried, possibly within a cocoon, as do many arid-adapted living anurans,” Evans and coauthors write, “emerging to feed and reproduce during periods of wetter and/or cooler conditions.” Finding direct evidence of such behavior is going to be tricky, especially for a species mostly known from disarticulated bits and pieces, but the hypothesis brings up a new vision that flips the frog’s reputation as the terror of small dinosaurs. Perhaps, while in their dry season slumber, estivating Beelzebufo were juicy snacks for little Majungasaurus in search of food and water. The devil frog might have been emergency dinosaur chow.


Evans, S., Jones, M., Krause, D. 2008. A giant frog with South American affinities from thee Late Cretaceous of Madagascar. PNAS. 105, 8: 2951-2956

Evans, S., Groenke, J., Jones, M., Turner, A., Krause, D. 2014. New material of Beelzebufo, a hyperossified frog (Amphibia: Anura) from the Late Cretaceous of Madagascar. PLoS One. 9, 1: e87236.

Fossil Frog Still Looks Gooey After Over 34 Million Years

In a blog posted late last year, paleontologist Sarah Werning made an important point that has stuck with me ever since – we need to stop apologizing for the fossil record. There are gaps and discontinuities and an astonishing amount of as-yet-undiscovered history, but a great deal of what has been found so far is truly exceptional. Werning picked prehistoric frogs as a prime example – several specimens of Liaobatrachus preserved in such detail that researchers were able to examine how the skeletons of the frogs transformed from cartilage to bone. A new look at a specific fossil amphibian discovered 140 years ago reminded me of her point. In a PLoS One paper, Fabien Laloy examine an Eocene frog that still looks gooey after over 34 million years.

Views of the fossil frog Thaumastosaurus gezei. From Laloy et al. 2013.
Views of the fossil frog Thaumastosaurus gezei. From Laloy et al. 2013.

The point of the study by Laloy and coauthors was the resolve the identity of this amazing find. In 1873, the French naturalist Henri Filhol briefly mentioned a fossil frog discovered among the Quercy Phosphorites of southwestern France that included an external cast of the amphibian’s soft tissues. The specimen, a head and body with an associated leg, looks less like a fossil and more like the crispy remains of a modern frog left out in the sun too long.

In his later writings, Filhol named the frog Rana plicata. This left later paleontologists with a taxonomic knot as the name was preoccupied, and no one really knew exactly where the frog fossil came from and therefore how old it was. When they CT scanned the fossil to see if there was anything inside the lovely exterior, Laloy and coauthors found the clues to finally resolve the mystery. Filhol’s frog had a skeleton “almost identical to that of Thaumastosaurus gezei“, another frog found in the same deposits. That narrows down the age of the beautiful cast to between 40 and 34 million years ago, and also helps constrain ideas about which frogs Thaumastosaurus gezei was most closely related to.

Internal view of the bones inside the frog cast. From Laloy et al. 2013.
Internal view of the bones inside the frog cast. From Laloy et al. 2013.

But the new study immediately caught my attention because the frog Filhol first described is so beautiful. Paleontologists often deal with scraps and fragments of prehistoric life; broken clues such as bits of dinosaur bone eroding out of a hill or tatters of an ancient leaf. These natural curiosities are pretty in their own way, but to be able to see the face of a frog that died over 34 million years ago is a stunning opportunity that is about as close as we may get to actually traveling back to the Eocene. The fossil record is incomplete, just as modern ecosystems are not recording every single jot and tittle of life, but the fact that such tender remains exist at all is an unfathomable source of wonder.


Laloy, F., Rage, J-C., Evans, S., Boistel, R., Lenoir, N., et al. 2013. A re-interpretation of the Eocene anuran Thaumastosaurus based on microCT examination of a ‘mummified’ specimen. PLoS ONE 8, 9: e74874. doi:10.1371/journal.pone.0074874

A Blog by

“Deaf” Frog Hears By Using Its Mouth As An Echo Chamber

Gardiner’s frog shouldn’t be able to hear. This dime-sized amphibian doesn’t have the right equipment for it.

In your head, sound waves pass through the flappy bits of your ear and vibrate a taut membrane—the eardrum. On the other side, three tiny bones transfer these faint air-borne vibrations into the fluid-filled inner ear, amplifying them along the way. In the inner ear, little hairs detect the vibrations and convert them into electrical signals that travel to your brain. This is how you hear, and it all depends upon the eardrum and the three bones within the so-called middle ear. Without these structures, 99.9 percent of the energy of incoming sound waves would be lost.

Gardiner’s frog doesn’t have a middle ear or an eardrum. It ought to be deaf.

And yet, it sings. When Renaud Boistel used loudspeakers to play recordings of the frog’s calls, other males would start calling in response. So, how does this “deaf” frog manage to hear? Boistel has a possible answer—they use their mouths.

A delightful chart showing some of the world's tiniest frogs, all doing jazz hands. Credit: Xiaphias
A delightful chart showing some of the world’s tiniest frogs, all doing jazz hands. Credit: Xiaphias

Gardiner’s frog is one of the smallest amphibians in the world. At its maximum size of 11 millimetres, it’s barely bigger than a fingernail. It’s part of a whole family of tiny frogs called sooglossids, found in the Seychelles Islands off the east coast of Africa. All of them lack middle ears, but all of them can apparently hear their own calls.

To find out how, Boistel’s team at the University of Paris-Sud analysed the frog’s skull with a very high-resolution X-ray scanner. This showed that the inner ear is completely surrounded by a capsule of bone, which might help to conduct incoming sound. But when they ran simulations of sound waves travelling through the frog’s skull, they found that these were still severely weakened by the time they reached the inner ear, despite the adjacent bone.

The simulations also ruled out another possible idea—that earless frogs might use their lungs to carry vibrations into their inner ears. That might be true for some species, but Gardiner’s frog has small lungs that don’t make good contact with its sides. They’d be terrible sound transmitters.

Gardiner's frog, viewed through X-ray holotomography. Credit: Renaud Boistel
Gardiner’s frog, viewed through X-ray holotomography. Credit: Renaud Boistel

But the team’s simulations also revealed something odd—a burst of pressure within the frog’s mouth. When the team added the animal’s mouth to their simulations, they found that it resonates at a frequency of 5,738 Hertz. Sounds of this frequency cause the mouth to reverberate strongly, turning it into an amplifier.

And guess what the average frequency of the frog’s call is? It’s 5,710 Hertz—roughly an F note, four octaves above middle C.

Gardiner’s frog seems to have a mouth that’s perfectly adapted for amplifying the calls of other Gardiner’s frogs, compensating for the lack of a middle ear. And it probably helps that the tissues between the mouth and inner ear are unusually thin.

This might explain why, in Boistel’s playback experiments, Gardiner’s frog reacts to the calls of its own kind, but not those of other frogs. Maybe its own calls are the only things it can hear.

“The idea is fascinating,” says Albert Feng from the University of Illinois. He proposed a similar idea back in 2011, to explain how another tiny frog, the Kihansi spray toad, could hear. However, Feng says the evidence that Boistel has provided is still tenuous and inconclusive, and he thinks they need to test their idea through experiments. For example, they might keep the frog’s mouth open, or briefly fill it with moistened cotton balls to see if they can still hear.

Reference: Boistel, Aubina, Cloeten, Peyrind, Scotti, Herzog, Gerlach, Pollet & Aubry. 2013. How minute sooglossid frogs hear without a middle ear. PNAS http://dx.doi.org/10.1073/pnas.1302218110

More on animal hearing:

A Blog by

Why Fingertips Might Grow Back But Entire Limbs Won’t

If a salamander or newt loses its leg, it can just grow another one. Humans aren’t so lucky. If you cut off my arm, it won’t grow back. (Note: please don’t do that.)

But back in the 1970s, scientists showed that children can sometimes regrow the tip of an amputated finger, as long as there’s a bit of nail left over and the wound isn’t stitched up. Later, we discovered that mice have the same ability. But why is the nail important, and why can’t a finger grow back without it? A new study provides an answer to this longstanding mystery. As I wrote in Nature News:

Working with mice, researchers led by Mayumi Ito at New York University have identified a population of stem cells lying beneath the base of the nail that can orchestrate the restoration of a partially amputated digit. However, the cells can do so only if sufficient nail epithelium — the tissue that lies immediately below the nail — remains.

The process is limited compared with the regenerative powers of amphibians, but the two share many features, from the molecules that are involved to the fact that nerves are necessary. “I was amazed by the similarities,” says Ito. “It suggests that we partly retain the regeneration mechanisms that operate in amphibians.”

You can find out more details about this process over at Nature. Meanwhile, you might also enjoy this long piece I posted a few months back, about whether we’ll ever regenerate limbs. It covers what happens in salamanders, why we can’t do the same, why these abilities have been so difficult for scientists to study, and whether we’ll ever be able to duplicate a salamander’s prowess to heal amputees. Here’s a taster:

Despite these hurdles, we know the basic steps that a regenerating limb must go through. After an amputation, cells from the outermost layer of skin climb over to seal the wound. At this point, humans would lay down lots of scar tissue, and that would be that. But in salamanders, the new cells transform into a structure called the wound epidermis, which sends chemical instructions to those below it. In response, nerves in the stump to start to grow again, while mature cells such as muscles and connective tissues revert to an immature mass called a blastema. This is what restores the limb. Regeneration is about taking a few steps back to take many steps forward.

“Somehow, the cells know their positions, and they’ll only regenerate what’s missing,” says Enrique Amaya, developmental biologist at the University of Manchester. If the limb is amputated at the shoulder or hip, the blastema creates the full leg. If it’s amputated at the wrist, the blastema makes just a hand and digits. As they grow and divide, the cells take up specific positions, so they know up from down, or left from right. They fashion a miniature version of the full limb, which eventually grows to full size.

The basic outline is there, but the details have been hard to fill. Why does the wound epidermis form, and what does it do to the cells beneath it? The limb won’t regenerate if the nerves inside don’t start growing, but what exactly do the nerves do? When cells in the stump rewind their fates to become a blastema, how far back to they go?


A Blog by

Reports of Frog’s Extinction Have Been Greatly Exaggerated

It’s been an eventful 75 years for the Hula painted frog. Having clung to existence while its closest relatives embraced the cuddle of extinction, it was then discovered by scientists, lost for decades, declared extinct and turned into a symbol of a conservation crisis, before literally hopping back into the limelight. It’s the Frog That Lived, Then Died, Then Lived Again.

The Hula painted frog was discovered in March 1940, when Heinrich Mendelssohn and Heinz Steinitz spotted two beautiful individuals in the wetlands of Israel’s Hula Lake. They had distinctive dark bellies with white spots, and streaks of olive, black and rust on their backs. A third adult was found in 1955, and that was the last anyone saw of it for decades. Many searched; none succeeded. In the meantime, the wetlands of the Hula Valley had been drained to make way for encroaching farmlands.

With its habitat degraded and its presence undetected, things didn’t look good for the frog. In 1996, after four decades of failed searches, it became the first amphibian to be classified as extinct by the International Union for Conservation of Nature (IUCN). That, unfortunately, was an omen of things to come. We now know that frogs and other amphibians are among the most threatened of all animal groups. Around a third of them are classified as “threatened” and up to 165 species might already have gone extinct. Their habitats are disappearing. Pollution is killing them. A deadly fungus is wiping them out.

The picture is certainly bleak, but that might partly be because many amphibians live in inaccessible places and are hard to find. They were seen once, maybe twice, and then never again. Have they actually died out, or are there small populations clinging onto life? If it’s the latter, we could double our efforts to protect the survivors, or enrol them in breeding programmes. But first, we’d have to find them.

To that end, Conservation International launched the “Search for Lost Frogs” in 2010—a huge search for 100 species that hadn’t been seen for at least a decade. They only found four of their wishlist, such as the Rio Pascado stubfoot toad, re-discovered after a 15-year absence. These were small consolations for a project that otherwise failed. The world still needed hopeful stories.

Enter—or perhaps, re-enter—the Hula painted frog. Since the last individual was seen, the lake where the frogs lived had been turned into Israel’s first nature reserve. Protected against the devastating drainage  project, it became a haven for migrating birds, rare plants, and fish. Yoram Malka, a range for the Israel Nature and Parks Authority, was convinced that the painted frog was still there. He had no evidence, just a gut feeling.

In 2010, Malka relayed his suspicions to Sarig Gafny, a river ecologist from the Ruppin Academic Center in Israel, who was studying invertebrates at the lake. “I told him: Until you get me a frog with a black belly and white spots, you don’t have it,” says Gafny. “He said: Give me a year and I’ll get you a specimen.”

Exactly one year later, in October 2011, Gafny returned to his office in the late afternoon to find 20 missed calls on his phone. It was Malka. Earlier that day, on a routine patrol, a Hula painted frog has just leapt out in front of him. “He told me: Sarig, we found it.” Gafny jumped into his car and drove to the reserve, armed with a copy of the original 1943 paper describing the frog. He checked off every physical feature against Malka’s specimen. It was indeed the right animal, in the not-extinct flesh.

Hula painted frog at the Hula Nature Reserve. Credit: Frank Glaw.
Hula painted frog at the Hula Nature Reserve. Credit: Frank Glaw.

The frog’s reappearance is doubly important because it turns out to be the last survivor of an otherwise extinct genus called Latonia. Back in the 1940s, Mendelssohn and Steinitz classified it as Discoglossus nigriventer, making it one of several Discoglossus painted frogs. “It was a reasonable classification because they didn’t have DNA sequencers or CT scanners as we have now,” says Gafny. But when his team analysed the DNA from their newly-found specimens, they found that the frog isn’t part of the Discoglossus group, and had split away from them around 32 million years ago.

So what was it? Rebecca Biton from the Hebrew University of Jerusalem had the answer. She had been studying the bones of fossil frogs found in Israel, and showed that many “Discoglossus” skeletons actually belonged to Latonia. She eventually worked with Gafny and placed the four dead Hula painted frogs in a CT scanner. Sure enough, their bones had the distinguishing marks of Latonia, corroborating the story that the DNA had crafted.

There are no other living Latonia species. The rest died out during the Pleistocene period, with the last one living to around 15,000 years ago.  If the Hula painted frog—now Latonia nigriventer—had actually gone extinct in the 1950s, its entire genus would have disappeared too.

Gafny’s team have now found a total of 14 individuals. (Their new paper says 11 but they’ve found three more since, and one just in the last week!) One had been killed by a farmer (by accident) and three had been killed by kingfishers (probably not by accident). The rest were alive. And when news of the rediscovery broke in 2011, Gafny got an email from a tourist who had snapped a photo of a Hula painted frog two years earlier! “Our finding got so much media exposure that it reminded him of something, and he went back to his camera,” says Gafny.

“Rediscoveries like this are important in fostering interest in conservation and a generating sense of optimism,” says Robin Moore, who works for the IUCN and has visited the Hula Nature Reserve with Gafny.  “We need flagships for conservation to generate a sense of optimism and this story is about as good as it gets. The frog became a symbol of extinction in Israel. It is even included in school curricula, and my taxi driver to Tel Aviv airport knew its story!”

But if the frog was there the whole time, why could no one find it? Because, Gafny thinks, they weren’t looking hard enough. That’s not a slight; the frogs have only been found around a single pond and they live among dense vegetation. “You have to crawl into this very dense canopy of blackberries, which aren’t very polite to you,” says Gafny. “Then you have to dig into the decaying vegetation. They usually sit covered by leaf litter.”

The more hopeful answer is that the frogs’ population is increasing. Gafny says that the water in the lake has become cleaner and more plentiful since the nature reserve was set up. He hopes that by continuing to protect this delicate ecosystem, he can give the frogs a fighting chance. He’s especially hopeful because the deadly chytrid fungus that is killing frogs all over the world has never been found in the region. “I’m looking for it just in case, but we have no record of it,” says Gafny.

“Habitat loss remains the biggest threat to the survival of amphibians around the world, and it’s important to be reminded that strategies to address it can work,” says Moore, “We need these positive stories amid the doom and gloom.”

Reference: Biton, Geffen, Vences, Cohen, Bailon, Rabinovich, Malka, Oron, Boistel, Brumfeld & Gafny. 2013. The rediscovered Hula painted frog is a living fossil. Nature Communications http://dx.doi.org/10.1038/ncomms2959

Note: A shorter version of this story appears at Nature News.

More on frog conservation:

A Blog by

Unfussy Female Poison Frogs Just Go For Closest Male

A female strawberry poison frog faces an abundance of choice when it comes time to breed. The forest floor is full of bright red males trying to attract her with their songs, and wrestling with other males to defend their territories. She could pick a suitor based on his size or health. She could weigh up the quality of his territory. She could judge him on the depth, volume or length of his croaking, any of which could indicate how strong he is.

Or she could just mate with the first male she finds.

That, rather anticlimactically, is exactly what happens. For all the effort that males put into attracting a partner, the only factor that seems to matter to the females is who’s nearest. And according to Ivonne Meuche from the University of Veterinary Medicine in Hanover, this strategy makes perfect sense for these frogs.

The strawberry poison frog (Oophaga pumilio) has become something of a celebrity among scientists studying frog behaviour. It’s easy to find because of its bright colours and tendency to hop about in the day. And it has lots of sex. On average, a female will only go for 4 to 5 days between partners.

The frogs practice ‘lekking’—a style of mating where many males call at the same time, allowing females to choose between them. Each male defend a small territory, and each female wanders across many of these. When she chooses a mate, the two partners face in opposite directions while she lays eggs and he fertilises them.

Meuche’s team followed 20 female frogs in the rainforests of Costa Rica to see which males they mated with. They compared the qualities of these victors to those of every other male within the females’ home ranges. They also compared the two males that were closest to the females on the morning of their egg-laying days.

In an earlier study, one of the team, Hieke Prohl, suggested that males mated with more females if they called more often and at a lower pitch. But this time, they found that females were completely oblivious to the males’ territory size, weight, length, health or calls. Instead, they just went straight for the nearest one who was calling.

You could argue that females are making pickier choices the night before, so that they’re waking up near their favoured partners on egg-laying days. But in other studies, the team showed that the females’ whereabouts don’t depend on the males but on the availability of food.

They also checked their results by using two speakers to play recordings of males with different call rates and pitches. Forty-five females heard these calls and none of them seem to care about the calls themselves. They just went for the closest speaker.

This is unusual. Lekking is almost synonymous with female choosiness, although some other frogs also use a “closest-male-wins” strategy. It presumably means that they sometimes mate with dud partners while there are prime specimens calling a bit further away.

But Meuche thinks that the females aren’t fussy because there are big costs to shopping around. In this corner of Costa Rica, female strawberry poison frogs outnumber the males. Males are in short supply, and if they’re with another female, they stay silent and cannot be found. If a female rejects a male, she might not be able to find another partner, much less a better one. If this happens, she’ll lose an entire clutch. On her egg-laying days, she has to find a mate within a certain time or she’ll just lay unfertilised eggs that never develop.

The team also found that the males are all much of a muchness. They compete so intensely for territories that those with good ones, which put them closest to as many females as possible, will probably also have good genes. Females have a good chance of getting a high-quality mate even if they grab the closest one.

Reference: Meuche, Brusa, Linesenmair, Keller & Prohl. 2013. Only distance matters – non-choosy females in a poison frog population. Frontiers in Zoology http://dx.doi.org/10.1186/1742-9994-10-29

More on frog sex:

A Blog by

Resurrecting the Extinct Frog with a Stomach for a Womb

Two years ago, Mike Archer from the University of New South Wales looked down a microscope and saw that a single fertilised frog egg had divided in two. Then, it did it again. And again. Eventually, the egg produced an embryo containing hundreds of cells.

“There were a lot of hi-fives going around the laboratory,” says Archer.

This might seem like an over-reaction. After all, millions of frog eggs divide into embryos every day, as they have done since before dinosaurs walked the earth. But this egg was special. Archer’s team of scientists had loaded it with the DNA of the southern gastric brooding frog—a bizarre creature that has been extinct for almost 30 years.

The fact that it started to grow into an embryo was a big deal. The fact that it never went further was disappointing, but not unexpected. This is cutting-edge science—cloning techniques put to the purpose of resurrection.

Archer’s goal is simple: To bring the extinct gastric brooding frog back from oblivion and, in doing so, provide hope for the hundreds of other frogs that are heading that way. Getting the embryo was a milestone and Archer is buoyantly optimistic that he’ll cross the finish line soon. Lazarus, he says, will rise again.

Frozen southern gastric brooding frog. Photo by Bob Beale
Frozen southern gastric brooding frog. Photo by Bob Beale

Stomach for a womb

The southern gastric brooding frog (Rheobatrachus silus) was discovered in 1972 in the mountains of Queensland, Australia. But the world only took notice of it in 1974 when Mike Tyler discovered how it reproduced.

Simply put, the mother frog converts her stomachs into a womb. She swallows her own eggs and stops making hydrochloric acid in her stomach to avoid digesting her own young. Around 20 to 25 tadpoles hatch inside her and the mucus from their gills continues to keep the acid at bay. While the tadpoles grow over the next six weeks, mum never eats. Her stomach bloats so much that her lungs collapse, forcing her to breathe through her skin. Eventually, she gives birth to her brood through “propulsive vomiting”, spewing them into the world as fully-formed froglets.

When news broke about this weird strategy, other scientists were incredulous. Tyler provided vivid accounts of a young frog poking its head out of mum’s mouth like an amphibian Russian doll, but even these were insufficient. “It just seemed to many zoologists absolutely impossible,” he later wrote in a book. “There were frequently insinuations that somehow we were wrong.”

It took many years, field surveys and photographs to persuade the naysayers. Tyler eventually published a full description of the frog and its behaviour in 1981. (Nature rejected the paper because they—wrongly—deemed it uninteresting.) The medical community took notice. If this creature could deliberately stop making acid in its stomach, it might provide new ways of treating stomach ulcers or helping people who go through stomach surgeries to heal more quickly. Several teams started studying the frog.

They didn’t have long. “There was intense interest and all of a sudden it was gone,” says Archer. The last specimen was seen in the wild in either 1979 or 1981 and despite extensive field surveys, none was ever found again. The last captive individual died in 1983, and the species was no more.

Then, good news! A second species—the northern gastric brooding frog (Rheobatrachus vitellinus)—was discovered in 1984 in Queensland’s Eungella National Park. But a year later, almost before anyone could uncork the celebratory champagne, it too went extinct.

Archer, however, is in the business of de-extinction. He’s going to clone the southern gastric brooding frog back into life.

A barred frog provides surrogate eggs for cloning the southern gastric brooding frog. Photo by Bob Beale
A barred frog provides surrogate eggs for cloning the southern gastric brooding frog. Photo by Bob Beale

Cloning Lazarus

Archer has several reasons for trying. There’s the medical potential. There’s the unusual nature of the frog’s life cycle, which no other animal shares. But really, it’s a more “transcendent reason” that drives him. “If we were responsible for the extinction of the species, deliberately or inadvertently, we have a moral responsibility or imperative to undo that if we can,” he says.

But hang on–no one really knows why the frogs disappeared or if we played any role. Human forestry might have contributed. Alternatively, the lethal chytrid fungus that’s currently triggering a global frog apocalypse might have claimed the gastric brooders as early victims. But Archer still holds to his “moral imperative” argument. He also figures that restoring the frogs might help to inform his other efforts, like a project to resurrect the thylacine—Australia’s charismatic “Tasmanian tiger”. “Maybe it would be easier to get something like the frog across the finish line,” he says. “And then people who were so negative might take a deep breath and back off.”

To clone the gastric brooding frog, the team first needed its DNA. Archer called up Mike Tyler, who rummaged through his freezers and found some old tissue samples. They were in shoddy condition—just bits of frog dropped in a container, without any antifreeze to protect them. The cells should have been useless, ruptured sacks but they had somehow stayed intact. “We thought it was worth a try,” Archer says.

The team then needed something to put the DNA into—the egg of another frog. He chose a barred frog—a reasonably close relative that produces large eggs of the right size. The downside—and it’s a big one—is that barred frogs only lay eggs once a year. “We had a few times when we went in and the frogs weren’t laying, and that was that for the year,” says Archer.

Once the team had their surrogate egg, they had to destroy the native nucleus so they could insert one from the frozen gastric brooding frog tissues. They either did the job manually with a very fine instrument, or bombarded the egg with ultraviolet (UV) radiation. They tried both techniques on hundreds of eggs and one of these eventually divided into an early embryo with hundreds of cells.

Every time the team has done this, the ball of cells starts to turn inwards on itself—a crucial moment called gastrulation—and stops. That’s where they are for now. They have the beginnings of a gastric brooding frog, but are a long way from even a simple tadpole.

Still, Archer is hopeful.  Whenever he has gone through the same technical motions with a living frog, and inserted the species’ nucleus into its own egg, the resulting embryo also paused at the same point. This suggests that there’s something wrong with the team’s techniques, rather than with Tyler’s frozen gastric brooding frog tissues. Busted tissues would be a deal breaker but technological problems can be fixed, and Archer has brought in stem cell expert Robert Lanza to help him do so. “We retain our vibrant optimism,” he says.

Southern gastric brooding frog, by Peter Schouten
Southern gastric brooding frog, by Peter Schouten

Is it worth it?

Archer has faced his share of naysayers, from those who think that the technological hurdles are too great to others who believe that restoring the dead is a vanity project. “If you were thin-skinned, you’d race to the corner and give up,” he says.

Some of the arguments against de-extinction don’t apply to the gastric brooding frog. Unlike the woolly mammoth or passenger pigeon, the frog isn’t a social creature that would need companions to learn from or travel among.  Unlike the mammoth, which would need to be born inside an elephant, the frog doesn’t need a complicated surrogate parent.  And unlike many of the candidates for de-extinction, like the moa or saber-toothed cat, the frog is small and can be reared in a laboratory. Archer has so much frozen tissue that once he successfully clones one frog, he could make a practically infinite supply of them.

“It seems like a good choice as a test case for many reasons, and I think is very defendable choice from scientific and ethical viewpoints,” says Karen Lips from the University of Maryland, who works on conserving living amphibians.

Archer believes that the project is not just defensible, but necessary. Frogs are in such a bad way that some conservationists are already trying to preserve tissue samples in a genetic ark, with a view to cloning these species should they ever disappear completely. “Everyone blissfully takes for granted that we’ll be able to do this down the line but no one has shown that you can,” says Archer. “This work will be relevant to the rest of the frogs around the world and possibly to animals of all kinds.”

Let’s assume Archer succeeds. Where would the new generation gastric brooding frogs live? Their habitat in the Queensland mountains is being threatened by feral pigs, invasive weeds and polluted or diverted waters. And then there’s the chytrid fungus, which has spread to almost every part of the world. It would be like releasing Lazarus into an ecological dystopia.

Archer is unfazed. “We can ultimately fix the wild,” he says. “Even if we had to maintain most of the world’s wildlife in artificial environments, that would be a thousand times better than to let them slide off the brink.” The frogs can wait until their homes are ready for them. In the meantime, scientists could perhaps engineer or breed them to be resistant to the chytrid fungus, or carry out experimental releases to see whether they would actually find a niche in this brave, new world.

But Lips argues that this is impractical. “Zoos are extremely limited in space,” she says, and the resurrected frogs would have to compete with the thousands of other amphibian species that are facing extinction—around 40 percent of the 7,000 or so that we know of. “We can’t keep them all in captivity at sufficient numbers to maintain genetic diversity.”

Lips has another concern: Resurrection projects take up a lot of money. Archer concedes that cloning research is initially expensive, but he says that costs will eventually fall. “I can’t think of what cloning Dolly must have cost and now it’s a routine technique,” he says.

Still, funding is a zero-sum game. There’s only so much cash to go around and conservationists need it to monitor animals that are still alive, work out why they are disappearing, and develop ways of saving them. There are plenty of cases where we know how to save a species, but can’t afford to do so. “I can’t help but think that we can’t even take care of what we’ve got, and now we’re going to invest in very expensive techniques to recover a handful of special-interest species that may or may not be able to survive in the wild on their own,” says Lips. As a best-case scenario, she hopes that these high-profile projects will help to drum up interest in saving a broader swathe of imperilled wildlife.

Archer sees it slightly differently—the plight of living species gives him even more recourse to bring back extinct ones. “No matter how many resources we put into looking after the environment, wildlife is no longer safe in the wild,” he says. “If we accept that maintaining biodiversity is important, we can’t assume that if you whack a fence up, everything’s going to be okay. You need to explore lots of parallel strategies.”