Introduce any animals with obvious characteristics.

Bats are the only mammals that have evolved real flying ability, and most of them also have a keen auditory orientation (or echolocation) system. All bats rest during the day and go out for food at night. This habit makes it easy for them to attack sleeping prey without being hurt by other animals or high temperature sunlight. Bats usually like to live in isolated places, such as caves, cracks, holes or buildings, and some live in trees and rocks. They always rest backwards. They usually gather in groups, ranging from dozens to hundreds of thousands.

Bats have well-developed pectoral muscles, keel-like processes in sternum and well-developed clavicle, all of which are related to their special sports methods. It can fly well, but it needs to glide when it takes off, and it is difficult to fly again once it lands. When flying, the hind legs extend backwards to balance. ?

Bats generally have the habit of hibernating. During hibernation, their metabolic ability is reduced, their breathing and heartbeat are only a few times per minute, their blood flow is slowed down, and their body temperature is reduced to be consistent with the ambient temperature. However, their hibernation is not deep, and they sometimes excrete and eat during hibernation, and they can return to normal immediately after waking up. Their fertility is not high, and there is a phenomenon of "delayed fertilization", that is, fertilization does not occur during mating before hibernation, and sperm spend the winter in the female reproductive tract. After waking up in the next spring, the mating females begin to ovulate and fertilize, and then get pregnant and give birth.