The combination of fluid and tiny hairs in the inner ear help the vertebrate brain interpret an organism’s position in space and provides a sense of balance. Although these vestibular systems evolved hundreds of millions of years ago, some species are no longer able to make good use of them. According to a paper published today (June 15) in Science Advances, pumpkin toadlets (genus Brachycephalus, and they’re actually frogs) from Brazil have evolved to such diminutive size that there isn’t enough of a vestibular signal to keep the amphibians stable while they jump.
Some species freeze while jumping away from predators in order to give the illusion of being a leaf blowing in the breeze and remain motionless even after landing. This doesn’t appear to be what’s happening with Brachycephalus species, however. While the frogs don’t quickly return to their feet, they do move once they hit the ground, as shown in the video below. Additionally, many Brachycephalus frogs are brightly colored and don’t have the leaflike camouflage of other species, further indicating it’s a balance issue rather than a predation avoidance strategy.