This phrasing feels misleading. There isn't a ratchet system. The tendon that curls the toes or "holds on" is pulled by gravity so no muscles are used holding the toes closed in the hanging position. To let go the bats use muscles to relax this tendon and uncurl their toes.
That's interesting, thanks for pointing that out. The phrasing came directly from this WWF article.
I came here for a "well-actually".
Thank you, it was informative.
Sloths use their curved claws in a similar fashion but if they die sleeping they hang out dead until they decompose, separate and drop.
I wonder if that happens to bats too.
Damn, nature, you nasty. All kidding aside, that's fascinating. No idea if that happens to bats.
Birds have something similar to not drop from a branch while sleeping. That's why their toes in death are curled together, those muscles are relaxed, so to speak
Don't some/all birds have mechanisms for "locking" their legs/feet so that effort it's required to stay upright on a branch?
