The poorest frog on the planet: As small as a fingernail, after evolution, it loses its jumping instinct

The leaps of frogs are considered the wonders of evolution. When you see a frog shrugging, squeezing its hips back and then bouncing on its legs – two of the most powerful bio-springs in the animal kingdom – the frog is performing a classic leap that makes brand for their species.

And then it flew through the air, stretching its legs like skillful long jumpers. The frog's front legs flexed before stretching forward, landing and supporting its entire bulky body as it sped away like a cannonball.

"Oppp", the frog stuck to the ground again after drawing a perfect parabola in the air. It all happened in the span of a blink of an eye.

Most frogs can jump 10-20 times their body length, averaging 1.5 meters. In particular, the South African spiked frog can jump up to 3.3 meters, which is 44 times their size.

With that ratio, a 1m7 long jumper must jump over a distance of 74.8 meters to break the frog record. The number is equivalent to the length of two Airbus A320 aircraft combined.

Now, if you want to beat the frogs in the long jump, you'll have to pick an opponent that's just right for you.

The good news is that there is such a clumsy frog. A frog will score 0 points in any of its jumps. Because they always dance like this:

The performance you just watched is part of a study published in the journal Science Advances. In it, scientists are trying to decipher why in the world there is a species of frog that jumps such vestibular jumps?

Richard Essner, a biologist at Southern Illinois University, Edwardsville, said all other frogs have a perfect jump, with "a very precise, controlled landing."

Particularly for this frog species, Brachycephalus (also known as pumpkin toad) they only perform to about half of the test. The frog was still in the air with all the hopes of its species placed on it, but the way it landed was unacceptable.

Its hind legs stiffened, the frog twirled around in the air like a ballet dancer but fell flat on its feet. Instead of landing gently with its forelegs, the frog sometimes hits its chest, sometimes hits its back and even its head on the ground.

And then it lay sprawled out, bawling there as a rebuke to God: Why would evolution create a failure like me?

Welcome to the story of the pumpkin toad: Frogs with vestibular jumps

First of all, you can call them toads, or frogs. All toads are frogs and belong to the genus Anura, meaning "adults without tails". They are the amphibians with the largest population on the planet with more than 7,500 species.

However, toads have been discriminated against because of their rough and clumsy appearance. Toads are mainly terrestrial, so their legs are not webbed, or crawling, and the hind legs are short.

On the contrary, not every species of frog you can call a toad. Because frogs have their own pride. Frogs have smooth skin, they spend more time in the water, have webbed feet and long thighs. Frogs therefore often jump higher and farther than toads.

So maybe, we should call them pumpkin toads appropriately (in fact, if you search for "pumpkin frog" on Google, the results are just dishes).

As mentioned, pumpkin toad has the scientific name Brachycephalus. They are commonly found living in the forests of southeastern Brazil. Pumpkin toad is one of the smallest frogs in the world, with a body length of only about 9.5-13.5 mm. Which means a toad like this can sit snuggly on your thumb.

Its closest relative, the flea frog (Psyllophryne), also rarely exceeds 10 mm in length. Then there are a variety of other small frog species that live in northeastern Brazil and Cuba such as B. darkside, B. margaritatus, B. pulex, Eleutherodactylus iberia and E. limbatus. All of them have a body size in millimeters.

The shrinking size is an evolutionary advantage of Brachycephalus toads, scientists say. These pumpkin toads require less food as they have small bodies. Moreover, because of their small body area, they can also hide better on the forest floor, huddling under dry leaves without being detected by large predators.

However, when a species of frog shrinks its body size, problems begin to arise. That is what makes pumpkin toads have such vestibular jumps.

In their new study, Richard Essner and colleagues examined the legs of pumpkin toads, to see if there was a problem with their toothpick-sized feet.

Essner discovered that the pumpkin toads only have three functional toes, less than other frogs, but their entire leg muscles are still functioning well. The frog's jumping technique is also no problem. They still bounce pretty high and far in the first half of the jump. The anomaly occurred only in the second half of the jump, when the frog landed.

They seem to be unable to determine their altitude, not to time their bodies in the air, and even lose their orientation on the ground.

To find out why, Essner and Marcio Pie, a biologist at Edge Hill University, UK, conducted an experiment. They gave the pumpkin toads and a CT scanner to see if there was a problem with the creature's vestibule?

Because if you compare their jumps with the gait and staggered falls of vestibular patients, there seems to be a remarkable similarity.

We know the vestibular system is like a gimbal in the brain, which stabilizes the image of the world we see, and keeps our bodies balanced.

The vestibular system is located deep in the ear canal, with three semicircular canals filled with fluid. These semicircular tubes are spaced 90 degrees apart, with a lining containing lots of tiny hairs. When we walk, the shaking of the body moves the viscous fluids in the semicircular canals of the vestibular system.

The shifting fluid causes the tiny hairs to swing back and forth with each movement, which sends these signals back to the brain, where our neural processing system analyzes the vibrations and cancels them out for vision and vision. The body always feels balanced.

That's when the vestibular system has problems, or when you step off a ferris wheel, the vestibular system and fluids are disturbed, causing you to be dizzy, unsteady and nauseous.

Structure of the vestibular system.

The problem with pumpkin toads happens there, too, inside the microcircle

It turns out that when a species of frog shrinks its body size, its brain and vestibular system in the cochlea are also shrunk to the limit. Scientists have previously discovered that small frogs can be deaf, preventing them from hearing their mates' calls during mating season.

The problem with pumpkin toads is even more serious. Essner and Pie said that when they looked at the vestibular systems in the cochlea of ​​these frogs, they were so small they were almost useless. All three semicircular canals containing fluid are surprisingly narrow. "We even have to measure them in micrometers," says Pie.

In fact, the pumpkin toad possesses one of the smallest vestibular structures ever recorded in a vertebrate, when they are still fully developed. And what are the consequences of that record?

Every time a pumpkin toad jumps into the air, the fluid in their vestibular system does not move, but is still stuck to the sides of the semicircular canal by friction. "It's like you're sucking on a glass of syrup while squeezing the straw, the liquids don't have the same acceleration as their motion," explains Marguerite Matherne, a mechanical engineer at Northeastern University.

This disruption caused the pumpkin toad to eventually fail to position itself in space. Although it jumped into the air, it didn't know when it was about to fall in preparation for a safe landing.

Essner and Pie call this clumsiness with a euphemism an "uncontrollable landing". All pumpkin toads, with all their jumps, make the same mistake. "They dance like crazy drunks all their lives," says Pie.

Now, if evolution has shrunk frogs to the point of losing their vestibular function, the next question is whether these frogs can survive in a complex world?

In fact, frogs' jumping instinct is what they have developed to escape predators. When a frog senses danger, it jumps. And you rarely catch them, right?

In fact, although pumpkin toads are clumsy, you rarely catch them, says Pie. "Sometimes the two of us looking for a whole day can only catch one," he said.

That's because the pumpkin toads used a different evasion strategy. When they are in danger, they will still jump. But the clumsy landing turned out to help the frog slip through the dense foliage of the forest floor. Now, the frog just lay there, motionless. It will be rare for any carnivores to find them again.

In Brazil, pumpkin toads still thrive. The rainforest floor also provides them with a lot of food, many insects that this tiny frog can still hunt and eat. During hunting trips, pumpkin toads move very stealthily and slowly, like chameleons.

At this rate, their vestibular system can still take on the task of balancing the body. "And they're still alive and well," Essner said. Only, I don't know, will evolution continue to shrink pumpkin toads and cause their vestibular system to lose more function?

"If the toads keep getting smaller, they may no longer have vestibular function," says Pie. At that time, it is unknown how they will have to walk and dance.