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Do Some Female Frogs Play Dead To Avoid Mating?

When you think of an animal playing dead, especially in North America, you probably picture the Virginia Opossum (Didelphis virginiana), commonly known in the region simply as a possum. It's such an iconic scene that anyone or anything feigning death can be said to be "playing possum."

Biologists call the behavior "tonic immobility," or sometimes "thanatosis," and until recently, it was associated almost exclusively with prey animals playing dead to escape predators. But Carolin Dittrich, a former post-doctoral staffer at the Natural History Museum in Berlin, noticed that some of the European common frogs (Rana temporaria) she was studying exhibited the behavior during mating, too. She published her findings in the journal Royal Society Open Science on Oct. 11, 2023.

Dittrich told Snopes via Zoom that Rana temporaria is an "explosive breeding" frog, meaning that they reproduce in a brief window of the year, and thousands of frogs gather in one area at the same time. In these species, the males often significantly outnumber the females and harass and coerce them into amplexus, which is the technical term used for mating in amphibians. Research prior to Dittrich's study suggested that female frogs in explosive breeding species are passive during the mating process, but she found the exact opposite.

In fact, Dittrich wasn't initially studying the behavior of the females at all. The experiment she ran was to determine whether male frogs had a size preference when selecting mates — that is, did they prefer a larger- or smaller-sized mate? In the experiment, one male was placed in a box filled with 5 cm (2 inches) of water and two females of different sizes, and their behavior was recorded via webcam for an hour.

"But they didn't show any size preference," Dittrich said.

Instead, Dittrich noticed three behaviors that the female frogs repeatedly used when they wanted to avoid mating: physically rotating away, mimicking a mating call and tonic immobility. Rotating away from the male was the most common strategy — since amplexus must occur with the male behind and on top of the female, the females would flip onto their back to push the male frogs underwater. Dittrich recorded that behavior in 83% of amplexed females, and it was almost always the first attempted strategy.

If rotation was unsuccessful, 48% of the amplexed females began mimicking mating calls, as if to communicate, "I'm a male frog, not a female frog." The tonic immobility was a last resort — 33% of amplexed female frogs stiffened their limbs, with "arms and legs outstretched from the body after being amplexed by a male."

Interestingly, smaller frogs were more likely to go into tonic immobility than larger frogs. Dittrich theorized this might be because tonic immobility is not a conscious condition, but a response to high levels of stress. Smaller females could be younger, less experienced and more prone to high levels of stress than larger females, and thus more likely to show tonic immobility.

Lindsey Swierk, an assistant research professor at New York's Binghamton University who was not involved with the study, told Snopes in an email that she thought Dittrich's study was a great look into how female frogs of explosively mating species avoid potentially dangerous situations.

"Mating balls of multiple males and a single female are nasty and can be fatal for females," she wrote. "Part of why I like this study is because it brings attention to the fact that females aren't just 'sitting ducks' in explosive mating systems."

Swierk said she hasn't seen tonic immobility in the species of frog she works with (Rana sylvatica), but she has seen females avoiding and escaping their mates in other ways. She also wondered about the efficacy of tonic immobility as an avoidance strategy, pointing out that some other species of frogs still attempt to mate with clearly dead females. Dittrich also pointed out limitations of her research, explaining that her experiment's laboratory setting is a far cry from a natural pond.

The findings placed the European common frog in a small group of animals who have gone into tonic immobility during mating. Previous research has described similar responses in a spider (Pisaura mirabilis), a newt (Pleurodeles waltl) and a dragonfly (Aeshna juncea). But some people were drawn to the behaviors Dittrich described for another reason: humans are always more similar to animals than we like to admit.

"I saw comments online of people saying things like 'feels like home,'" Dittrich said.

Sources

Bilde, Trine, et al. "Death Feigning in the Face of Sexual Cannibalism." Biology Letters, vol. 2, no. 1, Mar. 2006, pp. 23–25. DOI.Org (Crossref), https://doi.Org/10.1098/rsbl.2005.0392.

Dittrich, Carolin, and Mark-Oliver Rödel. "Drop Dead! Female Mate Avoidance in an Explosively Breeding Frog." Royal Society Open Science, vol. 10, no. 10, Oct. 2023, p. 230742. DOI.Org (Crossref), https://doi.Org/10.1098/rsos.230742.

"Female Frogs Fake Their Own Death to Avoid Unwanted Attention from Males: Study." ABC7 Chicago, 12 Oct. 2023, https://abc7chicago.Com/female-frogs-study-mating-season-common-frog/13903191/.

Humphreys, Rosalind K., and Graeme D. Ruxton. "A Review of Thanatosis (Death Feigning) as an Anti-Predator Behaviour." Behavioral Ecology and Sociobiology, vol. 72, no. 2, 2018, p. 22. PubMed Central, https://doi.Org/10.1007/s00265-017-2436-8.

Instagram. Https://www.Instagram.Com/p/CyyNCwht7k5/?Igshid=Y2NkYjk0MDhjYg%3D%3D. Accessed 15 Nov. 2023.

Jacobs, Phie. Tired of Aggressively Amorous Males? These Female Frogs Play Dead. Science, https://www.Science.Org/content/article/tired-aggressively-amorous-males-these-female-frogs-play-dead. Accessed 15 Nov. 2023.

Janssenswillen, Sunita, and Franky Bossuyt. "Male Courtship Pheromones Induce Cloacal Gaping in Female Newts (Salamandridae)." PLOS ONE, vol. 11, no. 1, Jan. 2016, p. E0144985. PLoS Journals, https://doi.Org/10.1371/journal.Pone.0144985.

Khelifa, Rassim. "Faking Death to Avoid Male Coercion: Extreme Sexual Conflict Resolution in a Dragonfly." Ecology, vol. 98, no. 6, June 2017, pp. 1724–26. DOI.Org (Crossref), https://doi.Org/10.1002/ecy.1781.

Möller, Anna, et al. "Tonic Immobility during Sexual Assault – a Common Reaction Predicting Post‐traumatic Stress Disorder and Severe Depression." Acta Obstetricia et Gynecologica Scandinavica, vol. 96, no. 8, Aug. 2017, pp. 932–38. DOI.Org (Crossref), https://doi.Org/10.1111/aogs.13174.

Tonic Immobility In RabbitsRSPCA. Http://www.Rspca.Org.Uk/adviceandwelfare/pets/rabbits/behaviour/tonicimmobility. Accessed 15 Nov. 2023.

Brazil's Mysterious Tunnels Made By Giant Sloths

By Sarah BrownFeatures correspondent

(Credit: Heinrich Theodore Frank)

These tunnels were once believed to hide religious fortunes deep in their chambers, but the real treasure is found in who – or what – created them.

In 2009, a farmer was driving through his corn field in the south of Brazil when he suddenly felt his tractor sink and lurch to one side, making the vehicle shudder to a halt. He jumped out and saw the wheel had sunk deep into the dry soil.

Much to the farmer's shock, the tractor had broken through what looked like top of an underground cavity. Hearing about this unusual find, researchers came to investigate and were surprised to find a tunnel nearly 2m high by almost 2m wide and about 15m long running across the field and right under the farmer's house. Deep claw marks embedded into the walls indicated its past occupant was not human.

The farmer had stumbled upon a puzzling subject in palaeontology that is still unfolding today. He'd uncovered a megafauna paleoburrow, a prehistoric tunnel dug through rock by what Luiz Carlos Weinschutz, a geologist and one of the scientists who visited the farmer's property, concluded was the work of a giant ground sloth or giant armadillo from at least 10,000 years ago.

These giant ground sloths, described in one paper as "a hamster the size of an elephant", were far removed from today's unhurried, tree-dwelling ones. They grew up to 4m long and walked on all fours, although research suggests some could stand and move bipedally. Almost 100 different species of sloths roamed the Americas between 15 million to 10,000 years ago alongside car-sized giant armadillos that also dug long tunnels through rocks in Brazil.

Giant ground sloths that grew up to 4m and could stand on two legs once roamed the Americas (Credit: Esteban De Armas/Alamy)

I had first heard about paleoburrows when I saw a report in 2015 about the discovery of a 100m-long tunnel dug by giant sloths in the northern state of Rondônia, the first to be found in the Amazon rainforest. Yet it was during a holiday in the opposite end of Brazil a few years later that I had the chance to visit one in real life.

How to visit Brazilian paleoburrows

- The Engenho Velho paleoburrow complex is found in the Jacinto Machado municipality (1.5 hour return hike).

- The Toca do Tatu paleoburrow, where visitors can see rock art, is found in the Timbé do Sul municipality along the Portal do Palmiro hike. Along the same route are the Três Barras paleoburrows in the Morro Grande municipality. (4-hour return hike)

Tip: It's advisable to hire an experienced guide who can provide safety equipment such as helmets, protective clothing, masks and gloves. Contact the park directly for further information.

During this trip, I visited the Southern Canyons Path Geopark that spreads across the states of Santa Catarina and Rio Grande do Sul, home to several paleoburrows. After an hour trek through a forest-clad canyon in the state of Santa Catarina, I reached my destination: a 2m-high tunnel carved into a large, weathered rock. Inside it was dark and cool, the curved surfaces buffed smooth from many millennia of coarse sloth hair rubbing against it. Distinctive long claw marks criss-crossed the walls. It felt like walking into an oversized rabbit warren.

Heinrich Theodor Frank, a geologist by profession and paleoburrow expert at heart, told me that upon entering any one of these tunnels, "you find an open book. You see, you feel that this was not made by humans." He was right.

Most paleoburrows nowadays are filled with sediments, although some remain completely or partially clear, such as the one I had visited and the one the farmer had uncovered. The farmer's 2009 discovery came at the beginning of a surge of interest in paleoburrows, after hundreds were identified in southern and south-eastern Brazil. In the last 15 years, more than 1,500 have been recorded in this region, clinching it the title of having the highest concentration of megafauna paleoburrows in the world.

Nobody knows for sure why the south of Brazil has so many. Most are in the states of Santa Catarina and Rio Grande do Sul, but Minas Gerais, another southern state, boasts some remarkable examples, including a 340m-long paleoburrow and a collection of six 40m-long tunnels that lead to 10m-wide by 4m-high chambers. In June this year, this site – the largest paleoburrow in the state – was brought under official protection to safeguard it from human activity.

Claw marks in the tunnels helped scientists conclude that they were made by ground sloths and giant armadillos (Credit: Heinrich Theodore Frank)

A handful of paleoburrows can be found across South America, although none have been recorded in North America. "It's something that has no logical explanation because the megafauna roamed across the continent. You should have tunnels in other places," said Frank.

It's something that has no logical explanation because the megafauna roamed across the continent

Some experts say that the concentration of paleoburrows in Brazil's south is simply because the region is a hub for palaeontology research. Others disagree, pointing to geographical evolution influencing different behaviours among species across the Americas, which at the time of megafauna was up to 10C colder than now and much drier.

For many years, locals and researchers believed the tunnels had been constructed by past civilisations and the claw marks were assumed to be the work of a pickaxe. Some paleoburrows contain rock art, such as the Toca do Tatu ("Armadillo Burrow") in the state of Santa Catarina, which appears to have a sun with rays radiating out and groups of triangles representing mountains engraved on its walls. But because the art is carved into the rocks and not painted, dating it is almost impossible, said archaeologist Lizete Dias de Oliveira. No-one knows for sure who made the rock carvings and what they mean.

Regional Indigenous communities likely knew of the paleoburrows' existence before they were scientifically identified, evidenced by the tunnels featured in their oral stories. The Kaingang people, who come from Rio Grande do Sul, tell of a legend that a giant flood forced their ancestral fathers to swim to the hilly peaks where they eventually dug their way through the mountains for shelter. Other tales from the Kaingang suggest they knew the burrows were made by megafauna. A folktale for children involves the story of a family that descended into a hole made by an armadillo to enjoy the abundance of food there, only to have their rope cut by a "white man" (a native name for a non-Indigenous person) who took over the land while they remained underground.

The Toca do Tatu ("Armadillo Burrow") in the state of Santa Catarina has rock art on the walls (Credit: Heinrich Theodore Frank)

The exact storyline of the myths varies, but for the Kaingang people, the accuracy is less important than the story itself. "For the Kaingang people, there are no myths because everything that is told by the older Indigenous people is considered true," wrote Cláudia Aresi in a research paper for the Federal University of Rio Grande do Sul about the cultural and territory transformations of the Kaingang people.

Another theory linked to the paleoburrows was that the tunnels held hidden riches left there by the Jesuits. It led to treasure-seekers ransacking caves for this supposed wealth, never finding anything more than dust and sediments. "Treasure hunters are a horror for archaeology. They disturb the soil and reverse it, so what is newer becomes older and what is older becomes more recent," Oliveira said, adding that this complicates studying sediments for additional clues that could reveal more about these tunnels.

You have to look for animals that have claws, then you only have two options: the giant sloths and the giant armadillos

In the end, it was the claw marks that helped scientists conclude that these tunnels were made by megafauna, in particular ground sloths and giant armadillos. "We analysed the bones of the animals that lived in this region in the last two million years. Animals such as horses, sabretooth tigers, elephants, they did not dig. You have to look for animals that have claws, then you only have two options: the giant sloths and the giant armadillos," said Frank.

Weinschutz is currently 3D-mapping paleoburrows in Santa Catarina to try to spot patterns in the tunnels that could reveal the biomechanisms of digging such large constructions, as well as searching for traces of ancient fur to help identify the species that made them. "It's still a new study, there are years and years of research ahead in this area," he enthused.

More than 1,500 paleoburrows have been recorded in southern and south-eastern Brazil in the last 15 years (Credit: Heinrich Theodore Frank)

The results may shed some light onto why these animals made such large tunnels. Most scientists propose that it was for nursing young, regulating body temperatures or even hibernation, although the exact reason remains a mystery. Experts suspect that each tunnel was made over the course of centuries or even thousands of years, suggesting that the sloths and armadillos lived in social family groups. "Each generation did a little more, so after all those years, they created one big cave," Frank said.

The megafauna, both the giant armadillos and giant sloths, must have "developed an absurd strength in their arms" to be able to cut through rock and tough sediments that even a pickaxe would struggle to pierce, said Weinschutz. Intrigued, I visited the Museum of Earth Sciences in Rio de Janeiro to see the skeleton of a fossilised sloth and get a sense of its size. Its elongated skull was the size of horse and its curved claw covered my outstretched hand.

As I held the claw, my thoughts went back to the paleoburrow I'd visited with the deep scratches in the wall, the true treasures of these ancient homes. Even though the ground sloths and giant armadillos of the past have long gone, their stories remain forever marked in the south of Brazil, bringing to life a world so mysterious to us today.

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How Kermit The Frog Became A Sassy Meme

Kermit the Frog has undergone quite an identity crisis over the years. The beloved children's character was originally known as the frog puppet on The Muppets, in addition to stints on Sam and Friends and Sesame Street.

But Kermit the Frog's strings have been pulled in a different direction in recent years. Now, Kermit's image is used in countless memes to express snarky comments, awkward social moments, and relationship woes.

Here's where the Kermit the Frog meme originated—and why this beloved green puppet continues to stand the test of time.

Kermit the Frog: meme origin

In 2014, an image of Kermit sipping on a cup of tea began circulating on social media. The image was taken from a shot of Kermit in a Lipton Tea commercial promoting the brand and the film Muppets Most Wanted.

Kermit starred in the commercial alongside familiar faces from the Muppets, such as Miss Piggy. After chaos ensues in the streets, Kermit encourages people to "be more tea." The brand slogan for this translates to "be more kind."

#ButThatsNoneOfMyBusiness

According to Urban Dictionary, "sips tea" is the present form of "sipping tea," which means to listen to good gossip from someone. Since Kermit is sipping tea in the meme, it was paired with the hashtag #ButThatsNoneOfMyBusiness and used as a snarky clapback or witty comment.

This skyrocketed the meme's popularity. Numerous Instagram and X (formerly Twitter) accounts were created to share Kermit memes, and the booming Instagram hashtag #kermitmemes gained over 660,000 posts, plus video compilations, and coffee mugs with the famous slogan.

Kermit even made an appearance on The Kelly Clarkson Show to discuss the meme.

Why are Kermit the Frog memes so popular?

The fanfare behind Kermit is enough to make any fictional television character green with envy. But what caused the children's character to become a household name?

Don Caldwell is a curator at the internet meme database Knowyourmeme.Com.

"[Kermit] is an incredibly recognizable and lovable character, so people feel comfortable using him to signal things about their identity," Caldwell told BBC's Newsbeat.

The memes work so well because Kermit's lighthearted personality is so far the opposite of the sassy persona that the memes convey. No one could ever picture Kermit the Frog actually sipping tea and ignoring a person in need because they're "none of his business."

Variations of the Kermit meme

Kermit the Frog isn't just known for sipping tea. Thanks to screenshots from The Muppets and the ubiquity of Kermit toys available in the real world, there are many more memes featuring the beloved frog.

Sad Kermit

"Kermit the frog funny" may be a popular search, but within the expansive walls of the internet exists a much more subdued version of him.

The image shows a Kermit puppet with its head looking down and its knees folded into its chest. After the puppet was found photographed in other positions, people demanded to know who was behind making Kermit look so sad.

BuzzFeed found the culprit: then-17-year-old Pinja Savolainen from Finland. She told BuzzFeed News that the Kermit doll belongs to her mother, who found it in a market years ago. One day after walking by the doll in the kitchen, she decided to take a picture and share it on Twitter.

"It was originally meant to be just a little joke, but then I realized it was actually pretty fun to photograph him so I decided to make it into a thread," she explained.

'Evil' Kermit

It turns out that Kermit has an evil side, too. Kermit's meme popularity continued to expand with the arrival of the character's take on the "devil-on-the-shoulder" scenario. This is the inner conflict a person feels when they feel tempted to behave badly.

The meme was first shared by Twitter user Anya who used the meme to demonstrate the temptation to steal a cute dog. Once the meme went viral, the internet used the image to poke fun at other common battles of good versus evil.

Want to make your own funny Kermit pictures? Become a puppet master by using Kermit user generators, such as this one. This is a tool that allows users to make their own memes by combining an image with text.

Kermit said it best: "It's Not Easy Being Green."

Neither is being a meme, but the world's favorite frog handles it well. His likeness has been twisted and contorted in so many ways that you never know what viral meme the internet will think of next.

We crawl the web so you don't have to.

*First Published: Nov 21, 2023, 3:09 pm CST

Sarah Kester

Sarah is a multi-platform editor and writer who has been covering various topics—lifestyle, health, and entertainment—for more than a decade. Her work has appeared in Travel + Leisure, Tracy Anderson, Vital Proteins, Healthline, Diply, and more.

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