Meet the Gastric-Brooding Frog

  • By Anna Rothschild
  • Posted 05.18.17
  • NOVA

These extinct frogs used to barf up their babies—and now scientists are trying to bring them back from the dead. Discover more in this episode of Gross Science.

Running Time: 05:29


Meet the Gastric-Brooding Frog

Published May 18, 2017

Today I’m going to tell you about one of my favorite creatures to ever grace this planet. It’s a frog that’s pretty bizarre but also weirdly sweet and adorable. Sadly, it went extinct just before I was born, so I thought I’d never get the chance to see it. But a few years ago, scientists tried to bring it back from the dead.

I’m Anna and this is Gross Science.

Gastric-brooding frogs were first found in Queensland, Australia in 1972. They looked pretty normal—just your average brownish, greenish frog. But there was nothing average about how they gave birth.

A female frog would lay her eggs, and a male frog would fertilize them externally. So far so normal. But then, the mother frog would swallow the eggs—around 40 of them!

You’d think this would be a terrible idea. After all, stomachs—whether they be frog or human—usually contain strong acid to break down your last meal. But the eggs likely contained a chemical that made the mother’s stomach stop producing acid. That meant the mother couldn’t eat during her pregnancy, which from a human perspective seems awful, but the frogs seemed to make do.

Eventually, tadpoles would hatch from the eggs. And the tadpoles would release mucus that contained more of that acid-blocking chemical. The babies would continue to grow in the stomach for another 6 weeks, getting so big that they’d compress the mother’s lungs. Luckily, these frogs could also breathe through their skin, so the mothers didn’t suffocate.

Finally, the tadpoles would metamorphose into baby frogs, and the mother would vomit them up—usually one at a time over a few days. Though, when provoked some were known to projectile vomit all their babies out at once.

While barfing up your babies’s kinda sweet when you think about it. Gastric-brooding, as this strategy is called, is a way to keep your babies close to you and safe while they’re most vulnerable. It’s really a lot like human pregnancy…only the babies come out the other end…

Anyway, there were two species of these frogs, but both went extinct by the mid-80s. The culprit was likely an invasive fungus—one that poses a major threat to amphibians worldwide, and that humans likely helped to spread around the globe. It’s called chytrid fungus and it affects a frog’s skin. Because frogs use their skin for crucial functions like breathing, staying hydrated, and regulating their temperature, the parasite can easily kill its victims. And it’s highly contagious—by 2013 it had put 42% of the world’s frog species in danger.

Losing all these frogs would be, in a word, devastating. Not only would it have major impacts on ecosystems worldwide, and be a loss of beautiful biodiversity, but there is so much we still have to learn from these creatures that might be beneficial to human health and well-being. Take the gastric-brooding frog. If we’d had more time to study it, maybe we could have learned more about how it turns off stomach acid production, potentially revealing some insights that could help humans with GI problems.

Consequently, back in 2013, some scientists began a project to resurrect the gastric-brooding frog. They took cells from a frozen specimen, cloned the DNA into the egg of another frog species, and ended up creating a living gastric-brooding frog embryo. It only survived for about three days, but they haven’t given up trying. And it’s made some researchers hopeful that “de-extinction”—the process of bringing extinct species back to life—will one day be a solution for reviving at least some of the valuable biodiversity we’ve lost, often due to humans’ impact on the environment.

Obviously, this is a controversial idea. And, I think most scientists would agree that de-extinction is a last-gasp effort in conservation. It in no way means we should stop protecting and preserving the at-risk species we have. That said, while I can’t speak to the ethics of the situation, I will admit that there’s a pretty big part of me that would love to see a gastric-brooding frog vomiting up its babies.




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Host, Writer, Animator, Editor
Anna Rothschild
Camera, Sound
Natasha Ishak
A Race to the Moon
Music Provided by APM


Original Footage
©WGBH Educational Foundation
Images of Gastric-Brooding Frogs Giving Birth
© Michael J. Tyler
Gastric Acid
Shutterstock/decade3d - anatomy online
John Snow Waking Up
Game of Thrones, HBO
Rheobatrachus silus
Wikimedia Commons/ThinkQuest
Baby Belly
Wikimedia Commons/David Roseborough
Wikimedia Commons/Forrest Brem
Wikimedia Commons/ Peter Daszak, Lee Berger, Andrew A. Cunningham, Alex D. Hyatt, D. Earl Green, and Rick Speare
Rain Forest
Wikimedia Commons/Karduelis
Forest of Sai Yok National Park
Wikimedia Commons/uploader
Atelopus zeteki1
Wikimedia Commons/Brian Gratwicke
M fasciolatus
Wikimedia Commons/user:LiquidGhoul


(used with permission from author)
Squeak Pack/squeak_10
Rolling in Chair 1_2
Produced by WGBH for PBS Digital Studios


Image of Gastric-Brooding Frog Giving Birth
© Michael J. Tyler


Want More Info?

Inhibition of Gastric Acid Secretion in the Gastric Brooding Frog, Rheobatrachus silus:

Not Exactly Rocket Science, National Geographic: Resurrecting the Extinct Frog with a Stomach for a Womb:

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