#funfactfriday Ever wonder why and how bats hang upside-down?
Unlike birds, bats cannot launch their bodies into the air from the ground because their wings don't produce enough lift. Resting up high in an upside-down position means they are always set to spread their wings and just drop to take flight. For other mammals, holding onto a resting place upside down would be exhausting, but bats have evolved highly specialized muscles and tendons in their lower body.
Relaxing the tendons and muscles in their feet makes their toes contract to grab their roost and they actually have to clench their muscles and exert energy to let go. This means that a bat will not fall from a roost unless it consciously lets go, even if it passes away in its sleep! They also have special one-way valves in their veins and arteries to prevent blood from rushing to their head.