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Toads Too Tiny To Balance (Making Them Clumsy)

EnolaGaia

I knew the job was dangerous when I took it ...
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This category of toads is so small their vestibular systems are under-developed, leaving them clumsy.
These Toadlets Are So Tiny They Can't Balance Anymore, And The Footage Is Ridiculous

Being tiny can certainly have its advantages. You need less food, don't take up as much space, and are harder for predators to spot.

But researchers have just discovered there's a limit to how small a backboned animal can get, while still retaining the ability to balance. Pumpkin toadlets (Brachycephalus) have miniaturized well beyond this limit, resulting in hilariously awkward acrobatics whenever they try to leap.

They crash land on their butts, backs, bellies, and even face – often bouncing before their Skittle-sized bodies finally come to a stop. Luckily the impacts don't appear to harm them. ...

Captivated by these toadlets' magnificently comedic tumbles, Southern Illinois University functional morphologist Richard Essner Jr. and colleagues used CT scans of the inner ears of 147 different species to try to pinpoint the issue.

"They're not great jumpers, and they're not particularly good walkers either," explains herpetologist Edward Stanley from the Florida Museum of Natural History. "They sort of stomp around in a stilted, peg-like version of walking." ...

Their jumping technique doesn't explain much either ...

Instead, the trouble was found in their heads.

When we move we rely on feedback from a system of fluid-filled chambers in our ears – our vestibular system – to tell us which way is up. As the liquid sloshes with our movement, fine hairs detect its orientation and speed, providing our brain with information it uses as our positioning system.

Although these frogs still have vestibular organs, they don't appear to be providing the right information for the frog to be able to correct its orientation.

"Even though the canals are as big as they can possibly be relative to their heads, they're still not big enough for the liquid to move at a rate that would allow them to maintain balance," says Stanley.

This is not the only challenge some Brachycephalus have with their ears. At least two species have such underdeveloped hearing equipment they're deaf to their own mating songs. ...
FULL STORY: https://www.sciencealert.com/these-absurd-frogs-are-so-tiny-they-ve-lost-all-ability-to-balance
 
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