It’s hard not to think of vampires when you think of bats, and while many bats are harmless and helpful fruit- and insect-eaters, not all bats play so nice. There are some that embrace their vampire connections, and they are known, quite unimaginatively, as vampire bats.

There are three species of vampire bat, and each is so unique that they are placed in a separate genus (Desmodus, Diphylla, and Diaemus, for those who are interested). You can find these extra-creepy bats in Central and South America. Their preferred habitats are in tropical and subtropical areas, and they require dark places for roosting, such as caves, wells, hollow trees and buildings.

A white-winged vampire bat. Image by The original uploader was Gcarter2 at English Wikipedia., CC BY-SA 2.5, via Wikimedia Commons

Vampire bats are not overly large animals, with all species ranging in length from seven to nine centimetres. They have greyish brown fur, and in general, look fairly bat-like. They do not have nose leafs life fruit bats — they make do with naked nose pads with grooves in them. Vampire bats are also more suited to moving on the ground than other bat species, using their wings to propel them across the ground in a bounding gait.

You may have guessed — or already know — why vampire bats are named after the mythological Transylvanian monsters. Yes, these bats do suck blood. Common vampire bats feed primarily on mammalian blood, while hairy-legged vampire bats and white-winged vampire bats are more partial to bird blood. They feed only at night, so you don’t need to worry about being attacked by vampire bats (or vampires) when the sun is out.

Vampire bats have distinct skulls and teeth that make feeding on blood easier. Image by Mokele, CC BY 3.0, via Wikimedia Commons

Subsisting solely on blood is a very specialized diet, and vampire bats have some amazing adaptations as a result. They have thermoreceptors in their noses, which are used to locate areas where blood flows close to their prey’s skin. There’s even an area in vampire bats’ brains that is similar in appearance and location to infrared receptors in snakes, as the bats are capable of using infrared to find blood on their prey.

Once the blood is located, the bats have to find a way to access it. They do this with their razor sharp teeth — teeth that lack enamel so they are always incredibly sharp. Once they slice into their poor victim’s skin, vampire bats use their saliva, which is full of anticoagulants, to keep the wound bleeding.

Vampire bats also have a special digestive system to cope with their sanguine diet. To get the nutrients they need, bats typically drink about 20 grams of blood per feeding — which is a lot for creatures that weigh an average of 40 grams. That added weight is a problem for flight animals, so the bats have to jettison some of that extra cargo before they take off and return home. Therefore, their digestive system is designed to digest the blood as soon as possible, and pass on the extra liquid to the kidneys so it can be excreted. Typically, vampire bats start to urinate within two minutes of feeding. That’s some pretty quick digestion!

Vampire bats roosting together in a colony. On cold days, even non-resident males are invited into the colony to help keep the other bats warm. Image by Uwe Schmidt, CC BY-SA 4.0, via Wikimedia Commons

While the picture I’ve painted of vampire bats is one of evil, blood-sucking monsters, vampire bats aren’t all bad. At least, they’re nice to (most) members of their own species. Highly social animals, vampire bats live in colonies consisting groups of females and a few resident males. Non-resident males are shunned and live in separate groups.

Within colonies, vampire bats may share food with bats that are related to them, or bats that they know. A vampire bat can go only two days without feeding, so often a starving bat will beg another for food when sources of meals are scarce. The donor bat will then regurgitate a bit of blood for the beggar to consume. The exact nature of these relationships is still being studied, but it just goes to show that vampire bats are not self-serving, malicious creatures.

Vampire bats have been known to carry rabies, but it is very rare for a vampire bat to pass the disease on to humans. So don’t be afraid of these amazing animals! They are also medically useful, with compounds in their saliva being used in medicine to increase blood flow in stroke patients. See, vampires are friendly after all!

Cover image by Uwe Schmidt, CC BY-SA 4.0, via Wikimedia Commons, cropped to fit