INTEREST in vampires never dies. Next week, the third World Dracula Congress begins in the Transylvanian mountains in Romania, followed by a conference on vampires in Budapest a few days later. Devotees attending lectures such as 鈥淕etting to know the undead鈥� will of course know that Bram Stoker, author of the 1897 novel Dracula, would have been well aware of the vampire bat when he invented his Transylvanian villain.
But just how closely does the vampire bat resemble the vampire of dark imaginings? For starters the bats are nocturnal, and when their 20-centimetre wings are folded up around their small thumb-sized body they can look as though they are wearing a cloak. What鈥檚 more, the bats do feed exclusively on blood 鈥� they require 30 millilitres a day, and are capable of consuming up to 60 per cent of their body weight. Although humans have been known to fall victim to vampire bats, the commonest of the three blood-drinking bats, Desmodus, go for the blood of cows and pigs, given the choice, while Diamus and Diphylla prefer bird blood.
But vampire bats don鈥檛 suck blood the way you might imagine. They have a sophisticated method of extracting a meal efficiently and painlessly. Once a bat has found a victim by echolocation, sound, smell or possibly even heat, it uses the heat sensor on its nose to locate an area of skin rich in capillaries. With its canine teeth it clips away a patch of fur before making a small cut in the skin with its incisors. The bat鈥檚 saliva contains a protein that stops the blood that escapes from the wound from clotting. It then gently laps up the blood with its grooved tongue. Not only does the victim rarely die, it usually isn鈥檛 even aware of the bat鈥檚 presence.
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Any trace of evil? On the contrary. Vampire bats鈥� very survival depends on them being unselfish. Because they risk starvation if they don鈥檛 feed for 2 or 3 days, bats that have had a successful night鈥檚 hunting will regurgitate blood for those back at the ranch.
Vampire bats may also prove to be of medical use. The rare anticoagulant protein in their saliva could be used to treat victims of acute ischaemic stroke. The protein has been nicknamed draculin, but its more technical name is DSPA 鈥� Desmodus rotundus salivary plasminogen activator. Although there is already an effective drug treatment for stroke, it can only be given safely within 3 hours of the attack, whereas DSPA may still be safe if taken many hours later. It seems to be more specific in targeting blood clots 鈥� and has shown much less potential for causing complications.
So even if vampire bats don鈥檛 have supernatural powers, they might one day bring you back from the brink of death.