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Australian ground frogs take the standard weirdness of frog reproduction and development to the next level...and then to the next-next level. From swallowing eggs to putting tadpoles in pockets, these amphibians are doing their own thing.

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We are so excited to show you these frogs! If you'd like to learn more about Australian frogs and see how folks filmed the pouched frog, check out this video from the cool people over at Pobblebonks & Kundagungans:

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Here in North America, we tend to think of Australia as a continent full of mammals, but weird. You got kangaroos instead of deer, wombats instead of woodchucks, and sugar gliders instead of squirrels. But what if I told you that some of Australia’s weirdest animals aren’t mammals at all? Turns out, Australia is full of  frogs that are also very weird.

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Meet the family of frogs known as Australian ground frogs or Australian water frogs. There are over 100 species in this family, and they’re mostly found on their namesake continent, and also live in Papua New Guinea and Tasmania.

Now, most frogs undergo metamorphosis. They go from egg to tadpole to frog, essentially rearranging their whole bodies in the process. And yes, we can take a moment to appreciate just how strange that seems to us, even though probably it shouldn't, because metamorphosis is thought to happen in something like 60 to 80% of all animals, so we’re actually the oddballs here.

But this family of frogs takes the standard weirdness of frog reproduction and development to the next level and then to the next-next level. Take, for example, the turtle frog. It lives underground in sandy burrows that it digs with its beefy arms. It doesn’t hop, and its diet is mostly made up of termites.

It’s not only incredibly goofy-looking, but it also just skips the tadpole stage. It lays eggs in the moist parts of its burrow, and then the turtle frog babies hatch straight from their eggs as tiny frogs, no intermediate step necessary. This has a name. It's called direct development, and it means that the frog doesn’t have to depend on having a water source available for laying its eggs. Turtle frog burrows stay humid enough to keep the eggs from drying out, even though they live in a relatively dry environment.

And it’s not the only frog in this family that has direct development, either. The sandhill frogs and the forest toadlet do this, too. Direct development has actually evolved in a bunch of different frogs, and it’s probably helped them spread into more diverse habitats.

But the turtle frog hardly seems weird at all when you compare it to the pouched frog. Now, the pouched frog does go through a tadpole phase, but the tadpoles do not live in pools of water. These frogs inhabit cool, wet forests, unlike the turtle frog, and females lay their eggs in a blob of goo on the ground under logs or leaf litter. They don’t actually need to be in water to hatch into tadpoles.

Both the male and female frogs guard the blob of eggs, and when the eggs hatch, the males crawl on over, because they’re also not hoppers, and they let the tadpoles climb up their body into little pouches on their hips, where they hang out for two to three  months while turning into froglets, which is odd enough on its own, but there’s an extra helping of weirdness here, too: the tadpoles don’t eat, even though some researchers have suggested that the whole point of being a tadpole is to eat.

Seriously, the evolutionary point of metamorphosis might be so that the young and the adults of the same species specialize in eating different foods, but these little guys just don’t. And, according to one study on the patterns of frog reproduction, that might mean that non-feeding tadpoles are a kind of intermediate step between regular tadpoles and direct development.

So maybe given enough time, the pouched frog will become a direct developer, like the turtle frog, but the weirdness of both of these frogs does not hold a candle to the most bizarre members of their family, the gastric brooding frogs. Instead of keeping their young in cute little hip pockets, the two species of gastric brooding frogs swallowed them.

A female would lay her eggs and then swallow them, and the eggs and tadpoles would secrete a substance that turned off her stomach’s ability to make hydrochloric acid to keep her from digesting them. The eggs would hatch into 20 to 25 tadpoles in her stomach and live there for at least six weeks, growing in size. They’d eventually get so big that her stomach would literally squash her lungs, so it’s a good thing that these frogs could also breathe through their skin.

Meanwhile, the mother frog wouldn’t eat at all during this whole time. And then, I mean, you know how this has to end right? It’s gonna get gross. After the tadpoles completed their metamorphosis, the mother frog would just barf them up, actually  vomiting them out as little froglets.

Now, I have to ask, why? Why would this strange and unique method of reproduction evolve in the first place? Well, the researcher who first discovered how these frogs reproduced speculated that they started out as direct developers, like the turtle frog and the sandhill frogs, and that cannibalism was the first step toward gastric brooding, but we don’t know for sure. There are other frogs who swallow their tadpoles and carry them around in their vocal sacs, for example. And unfortunately we may never know, because both species of gastric brooding frogs went extinct in the 1980s for reasons that are also not totally clear.

All hope is not lost, though! There’s a team of researchers actively working on de-extincting the southern gastric brooding frog. In 2013, they announced that they were able to transfer genetic material from frog tissue frozen decades ago into the eggs of a frog that is still around today, and some of those eggs started to divide, growing into early embryos before stopping. While they didn’t make it all the way to the tadpole stage, the team did confirm that the gastric brooding frog’s DNA was making copies of itself inside the eggs, which they think is a good first step toward de-extinction.

And who knows? Maybe they will succeed in bringing it back and making this family of weirdly reproducing frogs complete again. Being the frog that came back from the dead would definitely put this animal in the hall of fame of Bizarre Beasts.

The Bizarre Beasts pin club subscription window is open now until the end of September 5th, and this month’s pin is, drumroll, just wait for it. It’s a sandhill frog. There he is! Oh my God! He’s so good! It’s just. Ahhhh! Sign up today and you’ll get this frog pin in the middle of the month and pins after that around the time each new video goes live.

Follow us on Twitter and send pictures of you accessorizing with your Bizarre Beasts pin at @BizarreBeasts, and on Instagram and Facebook at @BizarreBeastsShow, for more weird frog facts. And, as always, profits from the pin club go to support our community’s efforts to decrease maternal mortality in Sierra Leone.

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