On a moonless, starless night the vampires come out to hunt for food. The faces of their victims twist as they struggle in pain, their teeth changing shape as they themselves become vampires. Vampire stories are many. But is it really true that bats suck human blood and pass on the bad habit to people? Life is not so dramatic and such ideas are products of the human imagination. Bats sucking blood? It's just their way of getting by and surviving!

Are all bats bloodsuckers? In fact, there are only three kinds of bat in the world that feed on blood, and all of them are found in Latin America. Two of them are already practically extinct, and very little is known about them.

Do vampire bats attack people? People should not flatter themselves: "Human" is not an item that appears on the bat's menu. Of course, just like snakes, if you disturb a vampire you could become a kind of light snack.

The prey of the vampire bat is so extensive as to include sea lions and pelicans that inhabit the regions of coastal northern Chile. Near human settlements, however, it prefers to feed on a variety of domesticated animals such as chickens, cows horses and pigs, which do not move about at night. It is said that dogs, being able to hear very high-pitched sounds, have a kind of defensive system and are not easy prey for the vampire bat.

Is the bite of the vampire fatal? A vampire bat can digest up to 40cc of blood in one evening, an amount so small that the victim will not feel any ill effects. However, because vampires have a good memory and return to feed on the same herd of animals again and again, their prey can gradually be weakened. Yet the real danger from the bite of the vampire is not loss of blood but rabies, although most bats that contract rabies die before they can pass it on.

Are vampires an agricultural pest? As a carrier of rabies, the vampire bat can actually cause high losses for ranches. But the blame cannot really be laid at their door. Researchers point out that before Columbus reached the Americas, vampire bats existed only in small numbers. The arrival of European settlers with livestock brought a new supply of food, and the following unprecedented deforestation that occurred allowed the raising of even more cattle. The result has been an unchecked expansion of the vampire bat to a degree where it has actually become an agricultural pest in some areas.

With large numbers of vampire bats spreading disease and causing heavy losses in livestock, over the past 30 years in Latin America there have been large-scale campaigns to restrict its numbers. Unfortunately, this has meant that many insect and fruit eating bats which are beneficial to people have been mistaken for vampires and been killed in large numbers.

Are vampire bats as vicious as Dracula? Zoologists think that vampires are the most fragile species of all the bats. Out of nearly a thousand species, only the vampire hunts a prey that is up to 10,000 times its own size. They spend much of their time on the ground so as to creep up on animals, so they often get crushed to death. The mortality rate is more than 50 percent, and is especially high among young vampires going out for their first bite. Choosing to feed on such large animals makes the lot of the vampire not an easy one.

Do vampire bats "suck" blood? In fact, the vampire bat does not actually suck blood as humans would like to believe. It licks it up with very rapid movements.

Because there is no need to chew blood. the vampire's teeth are actually smaller than those of other bats. Its front incisors are large and razor-sharp, however, enabling it to penetrate the skin of a sleeping animal without it feeling a thing.

The vampire can find areas on the back and neck with concentrated capillaries and a good supply of blood, which will flow up special grooves on the underside of its tongue. Its saliva contains an anticoagulant so it can drink quickly without the blood clotting. Researchers are at present working on recreating this anticlotting agent, which is far more advanced than anything that modern medicine has come up with.

The vampire bat can feed for up to 30 minutes, and absorb as much as its own weight in blood. Because blood is 80 percent water, the bat has a highly efficient system that, at the time of feeding, can absorb proteins and excrete excess water. No need then to worry about being too full to fly. This remarkable ability to rapidly absorb nutriments is also a miracle that the medical world is striving to understand.

In the world of bats the vampire is one of the more advanced species and has a high degree of social consciousness. In a colony of 70-80 bats, the brave, mature male bats will act as guards for the weaker females. What is even more surprising is that, when the opportunities of finding food are scarce, vampires will actually regurgitate blood to give to their hungry relatives. Has your view of vampire bats changed?

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(cartoon by Wu Hung-fu)