When it comes to the matter of animals that ingest and digest blood (a process called hematophagy), you might be surprised just how many there are. The long list includes bed-bugs, lampreys, Torpedo snails (a type of sea-snail), fleas, horseflies, and Geospiza difficilis septentrionalis – the “vampire finch” of the Galapagos Islands. It’s a bird which just happens to supplement its diet with fresh blood. Of course, the most famous of all the blood-drinking animals is the bat. More specifically: the vampire bat. There are no less than three kinds of vampire bat: the hairy-legged, the white-winged, and the common vampire bat, all of which have their origins in the New World.
Just like its horror-movie counterpart, this particular breed of vampire prefers to spend its time in places dominated by just one thing: darkness. Caverns, tunnels, abandoned buildings, and caves are among the most favorite abodes of the vampire bat. To say that the vampire bat is a unique creature is not an understatement. It uses what are termed thermo-receptors – sensory neurons – to identify those parts of potential prey where the blood is closest to the surface of the skin and easily accessible.
In terms of its attacks, and again just like its fictional, horror-movie-based counterparts, the vampire bat very often feeds on creatures that are sleeping, as this makes them far less likely to fight back. The brain of the vampire bat – and primarily the inferior colliculus, which controls how the brain interprets sound – is particularly honed to allow it to detect an animal that is specifically in the sleep-state.
There are other parallels between vampire bats and the likes of the characters in True Blood and The Strain. To survive, they have to keep drinking blood, almost endlessly. Studies have shown that vampire bats cannot go for more than approximately forty-eight hours without a significant amount of the red stuff flowing through their systems. Perhaps most fascinating of all is what happens when a vampire bat fails to find fresh blood. It will approach another member of the colony and, in a fashion that is still not fully understood, give a sign that it is in dire need of food. The other bat, in response, will regurgitate tiny amounts of its own, recent intake of blood, thus providing its fellow-vampire with much-needed nourishment. Yep, not just blood, but puked up blood!
Now, we come to the most important aspect of the life and feeding activities of the vampire bat. If it shatters some cherished assumptions, that’s too damned bad, but – contrary to what many people believe – vampire bats do not suck blood. Ever. Instead, when a bat lands on its sleeping prey, it makes a tiny incision, with its razor-sharp teeth, that provokes the flow of blood – in much the same way that blood flows to the surface of our skin when it’s cut. The bat then proceeds to lap the protein-rich blood, rather than suck it.
Rather incredibly, if the skin of the prey is covered in significant amounts of hair, the vampire bat has the ability to use its teeth to “shave” the hair away, thus allowing it to feed easier. Most ingenious of all, Mother Nature has taken steps to ensure the saliva of the vampire bat contains anticoagulants that prevent the blood of its prey from clotting. The blood, as a result, runs and runs – and runs even more.
To demonstrate the sheer speed and ability with which the vampire bat can feed voraciously on its victim, a fully-grown specimen can lap around fifty percent of its own body weight in less than half an hour. Count Dracula would be envious. The vampire bat has a near-unique digestive system that allows its stomach to absorb plasma from the blood. From there, it makes its way to the kidneys, and finally to the bladder. It’s a very quick process, too: from intake to urination, the passage of time is around one and a half minutes. And, like all of us, when it’s done feeding, the vampire bat finds a good place to settle down, relax, and let the process of digestion do its thing.