V is for Vampire Bats.

You may be excused thinking that vampire bats are the stuff of legend. Not only do they exist, there is actually 3 distinct species of vampire bat, belonging to their own genus. They are found in Central and Southern America; in hot, humid, tropical regions. Their actual habitats are usually extremely dark, meaning they are found often in caves or hollowed out trees. Increasingly, bats are being found in uninhabited buildings and can cause quite a shock for passing humans.

Vampire bats, like pretty much all bats, like to hunt at night. What has made vampire bats the centre of many horror stories and myths is that they feed on blood. This is called hematophagy and there are 3 different species of bat which have this diet: the common vampire bat, the hairy-legged vampire bat and the white-winged vampire bat. The vampires almost always feed on the blood of mammals. This is perhaps because mammals are much easier for the bats to detect because they have the ability to ‘see’ thermal areas of animals. This also allows them to identify the best part of the animal to bite; the best part being the warmest as this indicates the greatest blood flow. When they have selected which part to bite, they create a small incision in the skin and start to lick up the blood in a similar method to how a dog drinks water. If there is hair or fur on the bat’s victim, then the bat will use its canine teeth to ‘cut’ the hair in a similar method to a barber’s blade. This means the teeth have to be extremely sharp and this aided by a lack of enamel on the outer edges of the teeth.

One of the most important part for a bat’s diet is ensuring that the blood flows and they get enough of a fresh supply. In order to prolong the prey’s blood’s clogging mechanism, the saliva of the bat has special anticoagulants that inhibit blood clotting as well as compounds that stop the restriction of blood vessels near the surface. This allows for a constant, fresh supply of blood. This is important because the bat can drink over half their weight in blood in just 20 minutes. This is only possible due to special adaptations in their digestion. If they did not have an accelerated digestion, then the bat would be too heavy and too slow to fly away from any predators. The stomach lining rapidly absorbs the blood plasma, which is quickly transported to the kidneys. The vital nutrients are then absorbed and the excess liquid is sent to the bladder. This all means that after a 30 minute feed, a bat is able to urinate the excess liquid in just two minutes after feeding. The whole feeding process of a vampire bat is up to 2 hours – this includes leaving its habitat, finding prey and drinking the blood.

Bats have also be known to feed on humans. Whilst this is quite rate and will not cause immediate death, bats that feed on humans can be extremely dangerous to local populations. Bats are known for spreading rabies. Although only 0.5% of bats possess rabies, it is largely asymptomatic in bats and therefore they have little fitness change if they have the virus. This means that they may just be as likely to feed on a human as a ‘normal, healthy’ bat. Rabies is perhaps even more dangerous to humans in that it is much more transmissible to livestock than it is to humans. This can cause the death of the local food supply and therefore cause human starvation and death!

Bats aren’t all doom and gloom for human health. The unique properties of the bat’s saliva (as shown above) is currently being used in human medicine. Research is currently being undertaken in trying to use the anti-coagulate properties of the saliva in aiding stroke patients at restoring blood flow to the brain! Vampire bats have also aided humans in creating many different ‘monsters’ for horror films. The most obvious example is the character of ‘dracula’ a vampire who feeds on humans. This has been rebooted numerous times – including the recent vampires in the Twilight series! Vampire bats then have given us the ultimate monster of all – A shiny Edward Cullen!

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