Do Vampires Really Suck Blood From Their Victims?

By Howard J. Bennett

Now that Halloween is just around the corner, I thought I should say a word or two about vampires. Not the fake ones that lurk about in horror movies, but the real ones—vampire bats—that fly around at night!

There are more than 1000 species of bats in the world, but only three of them feed on blood. All three live in Central and South America.

Bats are nocturnal creatures. They sleep during the day and come out at night to feed. They live in caves, tree hollows, and buildings. The common vampire bat has a 6- to 8-inch wingspan and a body the size of an adult thumb.

Although movie vampires suck blood from their victims, vampire bats do not. Instead, they get their dinner in a more civilized manner. After making a tiny cut in an animal’s skin with their razor-sharp teeth, they lap up the blood with their tongues. Imagine licking melted ice cream from the side of an ice cream cone and you’ll get the idea how this works.

The common vampire bat feeds on horses, pigs, and cows, while the other two species prefer birds. Although vampire bats occasionally bite humans, we are not on their regular menu.

Blood contains chemicals that cause it to clot. That’s why you stop bleeding if you’ve been injured. All blood-sucking animals have chemicals in their saliva that keep blood from clotting. The chemical in a vampire bat’s saliva is called draculin, which is an obvious nod to Count Dracula, the most famous vampire ever.

On a good night, a vampire bat will consume half its body weight in blood. If an 80-pound kid tried to do that, he would have to drink 5 gallons! However, because vampire bats are so small, they drain only a tablespoon of blood from their host.

Blood is made up of solid elements like red and white blood cells and a watery substance called plasma. Because vampire bats ingest so much blood, they must eliminate excess water right away or they would be too heavy to fly. Luckily, they have very efficient kidneys and start to pee while they are still eating. That means their host’s body serves as both a cafeteria and a bathroom!

When vampire bats return to the roost, they meet face to face and groom one another. If one bat went unfed, another one will often regurgitate (throw up) blood to share his bounty. Would you do the same thing if your sister came home late for dinner one night?

Although the bite of a vampire bat is not itself dangerous, it can spread a serious disease called rabies. Therefore, if you ever see or hear about someone being bitten by a bat, tell a grownup right away. Unless, of course, it is a 4-year-old dressed up as a bat for Halloween. In that case, just give him a piece of candy.

© 2012 Howard J. Bennett. All Rights Reserved.
(First published in the Washington Post 10/27/08)

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