ttps:////»https://www.w3.org/TR/REC-html40/loose.dtd»>
Incredibly, they like to stay that way to save energy when taking off for a flight. “This way of sleeping has been very useful for bats. Flying uses a lot of energy and one of the moments when more energy is expended is during takeoff. When you are upside down, taking off is much easier because you use the force of gravity as an impulse”, says biologist Caroline Cotrim Aires, from the University of São Paulo (USP). If this position is so advantageous, why don’t birds hang around like bats? The answer may lie in the evolution of each group of these animals. “Bats have quadrupeds as their closest ancestors, while birds are closest to bipeds, in this case dinosaurs. In the process of adopting flight, quadrupeds developed their upper limbs, while the lower limbs were regressing. The bipeds, on the other hand, kept their lower limbs functional and firm to run when they were about to take flight”, says Caroline.
Although the vast majority of bats rest upside down, individuals of some species sleep lying down, resting their bellies in tight places such as tile gaps and holes.
In this strange position, gravity helps in the beginning of the flight
1 – Bats don’t get tired of staying upside down because they have an efficient system of locks in the tendons of the feet that ease the weight of the animal. The 180º twist in the position of the feet in relation to the body also makes it easier to stand upside down
2 – Thanks to the force of gravity, when the bat lets go it gains momentum to start flying without wasting energy. It’s an advantage over birds that need a little run to take off or even an initial jump before flight and wear out much more