Vampire Bats - Common, White Winged and Hairy Legged Blood Suckers
Blood suckers. Creatures of the night. Vampire Bats! They do exist and they do suck blood, including human blood. Fortunately among the three different species of bloodsuckers - Common, Hairy Legged and White-Winged Vampire Bats - only Common Vampire Bats feed on mammal blood and none of the bats will turn you into a vampire, though some of you may wish they could.
The worst result from a vampire bat bite is Rabies, a terrifying disease that can infect many animals and be transferred to people through an animal bite. Yet vampire bats attacking humans are uncommon. For all the unjustified fears people have about vampire bats, it's time to learn the truth.
Common Vampire Bat Feeding
Hunting and Feeding
Vampire Bats need to feed on blood every day and going a few days without will result in the blackness of death. Yet their choice of prey is big mammals or birds, dangerous prey that could easily kill them if they are noticed. Therefore nature provided them ways to feed stealthily without detection.
When the sun sets Vampire bats leave their dark hiding place, usually a cave or a hollow tree, to hunt. Upon finding a victim the bats target the juiciest blood veins using thermal sensors in their nose. Razor sharp and enamel-less upper incisors then painlessly pierce through flesh without any disturbance letting the prey sleep in peace. Enzymes within the bat saliva prevent blood from clotting while grooves within the tongue let the blood flow into the mouth. It's not sucking blood but instead lapping it.
Common Vampire Bat
Common Vampire Bat (Desmodus rotundus)
When someone says Vampire Bat, they most likely are thinking of the Common Vampire Bat found in Mexico and most of South America. Living in colonies averaging 100 bats, Common Vampires feed on mammal blood, not bird blood like the other two species of vampire making them a pain to ranchers due to the risk of disease in their livestock. The most abundant and well studied of the vampire bat species, Common Vampires have flourished due to the rise of domestic livestock in their territories.
Able to run and jump great distances, Common Vampires attack from the ground and feed for 20-30 minutes. Within minutes of feeding, they begin urinating plasma to lighten their load as they can drink over half their body weight in blood (about 1 fluid ounce) which would make them too heavy to fly. When they've finished feeding and urinating, they can gain flight by using their thumbs to push off the ground.
After returning home from feeding the Vampires groom each other. During this time, they can request a regurgitated meal from another bat if their hunt proved unfruitful. The shared meals are a necessity as not every vampire will always succeed in feeding and a bat successful tonight could be unsuccessful the following night. Usually a male Common Vampire would share blood with females or children. The other two Vampire species are assumed to have the same habit but it has not been as well documented.
White Winged Vampire Bat
White-Winged Vampire Bat (Diaemus youngi)
Unlike the Common Vampire Bat, White Winged bats are not as well studied and a rarer species who feed on birds, not mammals. Found from Southern Mexico to South America and Trinidad, the White Winged bat is unique from its two brethren species in that it has 22 teeth, a set of molars the other species lack and white wing tips, hence the name. Two cup sized glands hidden in the rear of its mouth can be pushed forward to emit a foul musky spray to show its dominance or agitation.
Needing to hunt frequently, the White Winged Vampire is a skilled branch climber and likes to target its avian and chicken prey by approaching from behind, hanging under a branch and using it as cover to stealthily approach its target. They lack much of the ground movement of the Common Vampire Bat.
The primary feeding area is the bird's backward-pointing toe or the hallux. Feeding from behind provides stealth and some protection as it painlessly bites the bird with razor sharp incisors while hanging from a branch, using the anticoagulant in its injected saliva to make the blood flow unceasingly for a while, letting the bat feed uninterrupted and unnoticed.
White Winged Vampires have also been seen to land or climb onto the backs of hens, causing the hen to crouch, letting the bat get its meal from the back of the birds head. Apparently the hen's reaction to the bat is the same as when it's mounted by a rooster.
Hairy Legged Vampire Bat
Hairy Legged Vampire Bat (Diphylla ecaudata)
Mostly unstudied and rare like the White-Winged Vampire, the Hairy Legged Vampire Bat has its own unique habits and adaptations. Named most likely for the hair near the back of its hind legs, the Hairy Legged Vampire has a well developed calcar growing out of its heel bone that works similar to an opposable thumb. While many bats have calcars, the other two vampire species lack such a predominant bone, and no bats make use of it like the Hairy Legged Vampire.
Using its teeth in similar methods to the other Vampire bats, the Hairy Legged Vampire feasts on birds blood, using its calcar to help hang from the bird unlike the White Tailed Vampire who stays attached to a branch. The focus of its bite is also near the waste and genital openings of birds unlike the White Wing Vampire who focuses on bird's toes.
How a Stroke Works
Medicinal Studies (Desmoteplase) for Strokes
One of the enzymes in Vampire Bat saliva called Desmoteplase or DSPA, has been studied as a way to break up blood clots in stroke patients. It's the same enzyme which enables vampire bats to easily lap up the blood of its victim by halting coagulation. High hopes were placed on the recent clinical trials that it could be a feasible alternative to t-PA, the only anti-blood clotting drug on market for helping with strokes. t-PA needs to be administered within 3 hours of the onset of the stroke. DSPA, on the other hand, showed it may be usable up to 9 hours after a stroke.
Original tests were done on mice back in 2003 and it had showed enough success to move up to human clinical trials which wrapped up towards the end of 2008. Unfortunately, the results which have been published this year (2009) have shown that the Desmoteplase did little better than a placebo. The disappointing results mean another trip back to the drawing board for finding stroke related cures, leaving t-PA still the only medicine on the market, limited though it may be.
More on Vampire Bats
- Common Vampire Bats, Common Vampire Bat Pictures, Common Vampire Bat Facts - National Geographic
Learn all you wanted to know about common vampire bats with pictures, videos, photos, facts, and news from National Geographic.
- White Winged Vampire Bats
A researcher's observations of captive White Winged Vampire Bats
- The Curious, Bloody Lives of Vampire Bats | Natural History Magazine
A great source for information on the White-Winged Vampire and Hairy Legged Vampire Bats
- The illustrated story of the Vampire bat
Good general knowledge about the Common Vampire Bat