The bats are the only mammals that have managed to perfect flight. They have managed to develop wings, but have started to have a nocturnal life, so in order to be more effective, they have developed their senses like the smell and hearing better, and also developed something new, echolocation. Because the eyesight was not really needed, the bats became almost blind, having very bad eyesight. The echolocation replaced their eyesight though, and it has proven as a very effective adaptation. It is an adaptation that manages to locate objects, food source, be it insects or flowering plants, as well as caves for shelter from predators and cold weather.
Typically in mammals, the gender of an organism is determined by the sex chromosomes. In the case of humans, this happens to be the X and the Y chromosomes. So as you may recall, if you are XX, you are female. If you are XY, you are male.
