vampire bat, name for the blood-drinking bats of the family Desmodontidae, found in the New World tropics. Vampire bats feed exclusively on the blood of living animals and are thus the only true parasites among mammals. There are three species ranging from Argentina to N Mexico. They are small (about 3 in./7.5 cm long), round-bodied bats with large, pointed ears and naked snouts. Unlike most bats, vampire bats can walk on all fours with the body lifted off the ground; it is in this manner that they approach their sleeping prey. The bat uses its razor-sharp incisors to make a neat incision, usually without waking the victim, then laps the blood with its tongue. Its saliva contains an anticoagulant that causes the wound to seep for several hours. Vampire bats parasitize a variety of animals, chiefly mammals. Although the quantity of blood they take is insufficent to harm a large animal, they are dangerous to livestock and humans because they transmit serious diseases such as rabies and Chagas's disease. Vampire bats live in caves, tree hollows, and houses. They are mutual groomers, and an effective method of reducing their numbers is to coat a captured bat with a sticky poison and release it; when the bat returns to its roost the poison will be licked by other bats. Members of another bat family, the Megadermatidae, of the Old World tropics, are known as false vampire bats. They are exclusively carnivorous but do not feed on blood. The generic name Vampyrus belongs to a large, fruit-eating bat of Central and South America that was once mistakenly believed to suck blood. True vampire bats are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Chiroptera, family Desmodontidae.