Meet the vampire bat

Photo by Oasalehm. Retrieved from Wikipedia on 10/06/2022.

I watched the movie Morbius over the weekend. It was… a movie. And not a very good one.

Some of the movie’s choices I can look past. Most fantasy / action movies require some suspension of disbelief.

Do I wish they had given more context about the character backstories? Sure.

Can I look past the absolute wildness it is to think merging human and vampire bat DNA would create a vampire? Absolutely.

Does it make any sense how Morbius keeps gaining different powers from his bat DNA? Not at all, but I’m still suspending my disbelief and can look past it.

I can even look past the disregard for lab safety all the characters appeared to have.

But what I can’t accept is the blatant disrespect Morbius had for vampire bats. They told so many lies about these little bats, and it’s unacceptable.

Good news, though: I’m here to set the record straight.

Three species

There are three species of vampire bats, and they’re all pretty small – a wingspan of just 12 – 15 inches and a weight less than 2 ounces. Vampire bats live in warm climates in Mexico, Central America, and South America.

Vampire bats are part of the mammalian family Phyllostomidae, or New World Leaf-nosed Bats. Out of the 160 known bat species in this family, only three have evolved to feed entirely on blood. Most of the other species eat fruit and plants, although some are carnivorous and feed on insects and frogs instead.

Of the three species, the most abundant and well-known is the common vampire bat (Desmodus rotundus). The common vampire bat usually feeds on mammals, usually livestock (since there are lots of farms and livestock in their range). The other two species of vampire bats, the white-winged vampire bat (Diaemus youngi) and the hairy-legged vampire bat (Diphylla ecaudata), prefer to feast on the blood of birds. They are also much less common than the common vampire bat, so I will be focusing on the common vampire bat for the rest of this post.

The struggles of blood-drinking

In case I need to say it: don’t switch to an all-blood diet at home. Obligatory hematophagy, or when you feed exclusively on blood to survive, generally isn’t a good strategy. Animals who are hematophagous have evolved to deal with the unique problems of blood-drinking: the potential for a lot of liquid to overwhelm the kidneys and bladder, a risk of iron poisoning, and dealing with a large amount of protein.

Vampire bats have a few key adaptations to deal with these problems. Their stomach is specially shaped like a windsock so that it can fill up like a water balloon. This helps them get as much water as possible out of their meal. Vampire bats also have leaky stomach cells that iron can easily seep into. This may seem like a bad thing, but stomach and intestinal cells are easily replaceable – the bats can shed the cells (full of iron!) and expel them in their poop to get rid of extra iron.

Vampire bats also have a few other adaptations that I just think are neat. For instance, they have fewer teeth than other bat species – they’re on an all-liquid diet, after all, and so don’t need to chew their food!

Vampire bats also have much more developed thumbs and hind legs than other bats. These let them walk, run, and jump, all things that other bats (having evolved to fly, not walk) can’t really do. And vampire bats are speedy – they can run at about 2.5 miles an hour. Being able to move around well on the ground lets vampire bats stalk and attack their prey from the ground, as well as move away from the body once they’re done eating. You can see a video of a vampire bat running on a treadmill here.

Look at those thumbs. Photo by Ltshears. Retrieved from Wikipedia on 10/06/2022.

It’s blood time

To find their prey, vampire bats use a mixture of sight, smell, and echolocation. When an exposed animal is found, the vampire bat will quietly and lightly get on their body. Vampire bats will then use their infrared perception to look for heat – this signals that blood vessels are close to the surface.

Once a good spot is found, the vampire bat will make a small incision in the skin of their prey. Then, they lap up the blood with their tongue like a cat; they don’t suck up blood like a straw!

Having sharp little teeth helps break the skin without waking their prey. Photo by Jennifer Krauel. Retrieved from Flickr on 10/06/2022.

A vampire bat will continue feeding for 20 – 30 minutes if all goes well and their prey doesn’t wake up. A special protein in their saliva called ‘Draculin’ makes sure that the blood doesn’t clot on their prey’s skin. But don’t worry, vampire bats don’t take that much blood from their prey – only about a single tablespoon.

Still, a tablespoon of extra weight is a lot when you weigh only 2 ounces! And remember, a risk of surviving on only blood is overwhelming your bladder and kidneys with liquid. To combat this, vampire bats begin urinating within just 2 minutes of eating. This allows them to shed the excess water weight from the blood so that they can be light enough to return to their roost.

Sharing is caring

Vampire bats are social animals that live in colonies of individuals typically between 20 and 150 individuals. Within these colonies, males will usually guard a small territory that houses his harem of 8 – 12 females and their pups.

Hanging together. Photo by Josh More. Retrieved from Flickr on 10/06/2022.

Vampire bat colonies are super important for a vampire bat’s survival. Blood isn’t very full of energy, so vampire bats can’t really make fat in their bodies to get them through a tough hunting night. In fact, a vampire bat will starve to death within just 2 days.

But don’t worry! Here’s where the colony comes in. Vampire bats will share their blood meal with individuals who were unsuccessful in finding prey that night by regurgitating a small amount of blood. This keeps all members of the colony alive and the colony stronger overall. Female vampire bats will also groom each other to strengthen bonds within the colony.

And vampire bats are sharing with us in their own way as well. Remember the protein in their spit, Draculin? Draculin is a very powerful anti-coagulant and has the potential to be used as a drug to treat heart attack and stroke victims.

So you see! Vampire bats are not that scary at all. They only drink a little blood, and most of their victims never even know they were there.

Of course, you should be careful if you sleep outside in an area where vampire bats are found. They will occasionally drink from humans. While the blood loss isn’t an issue, vampire bat bites can become infected if not treated properly. In addition, vampire bats do carry rabies, so you should make sure to get your rabies shot if you’ve been bitten!

But all in all, vampire bats are nearly as monstrous as Morbius would make you believe.


Texas Tech University



A-Z Animals



Scientific American

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