Vampire bats feed on the blood of warm-blooded animals such as birds, horses and cattle. They do not suck blood. The bats obtain blood by making a small cut in the skin of a sleeping animal with their razor-sharp teeth and then lapping up the blood as it flows from the wound. The bat's saliva contains an anesthetic that reduces the likelihood of the animal feeling the prick. Each bat requires only about two tablespoons of blood every day, so the loss of blood to a prey animal is small and rarely causes any harm.
Bats are blind.
Although they can't see color, bats can see better than we do at night. Bat Biology Bats, like humans, are mammals, having hair and giving birth to living young and feeding them on milk from mammary glands. By listening to the echoes reflected back to them, they can discern objects in their path. Bats are the only true flying mammals. The bones in a bat's wing are the same as those of the human arm and hand, but bat finger bones are greatly elongated and connected by a double membrane of skin to form the wing.