Vampires are mythical beings, right? Tales of the dark-natured, blood-sucking mischief makers have been spread far and wide across the ages. These undead monstrosities are familiar to most thanks to the spread of vampire superstition into Western Europe from the Balkans, where tales of their horrifying exploits were commonplace in the 18th century. Civilizations as ancient as Babylonia recorded tales of blood-consuming spirits over 3,800 years ago. But is there any truth to the legends?
Evolution has already produced quite a selection of truly terrifying creatures. Vampires are no exception to this menagerie of malevolence, so here is a selection of real-life vampires – technically known as hematophagous creatures – to share with you. Happy nightmares, everyone!
If You’re Prey, It Sucks To Be You
Image credit: oriontrail/Shutterstock
At this point, you might be wondering why certain creatures have evolved to feed in this way. Blood is actually a fluid rich in proteins and lipids (fats) that can be extracted from prey, often with minimal effort and completely undetected. Some creatures absolutely need to feed on blood, whereas others choose to if the opportunity arises.
Hematophagy has evolved several times independently in different lineages of animals over time – this is known as convergent evolution. It’s a form of parasitism: The vampire benefits by obtaining nutrients from a host at the host’s expense.
1. Lamprey
Image credit: NOAA/Flickr, CC BY-NC 2.0
There are 38 known still-living, or extant, species of this eel-like creature, whose ancestors have been slithering through the Earth’s oceans and freshwater rivers for at least 500 million years. The majority of these species spend their lives in quite unfrightening ways: Possessing no jaws, lampreys spend up to seven years as harmless, wobbly larvae. However, 18 species go on to grow up to be genuine monsters.
The sea lamprey – Petromyzon marinus – is one such monster, becoming a 90-centimeter-long (35.5-inch-long) parasite, sucking the blood of its fishy victims to survive. When the larvae metamorphose into adults, they develop a suction cup-like mouth. Latching onto its victim, it uses its probing tongue to begin to peel away at the fish scales getting in the way of its delicious crimson blood.
Its specialized teeth, strengthened by the same tough keratin fibers our hair and nails are made out of, are stabbed into the fish, cementing the sea lamprey’s grip. By assuring a continuous supply of blood using anti-clotting secretions, the victim typically bleeds to death or dies of an infection growing within their wound.
This particular vampire is known in some places as an invasive species, destabilizing the local ecosystem with its aggressive, hematophagous feeding frenzies.
2. Vampire Finches
Image credit: Simon J Pierce Photography, www.simonjpierce.com
The Galápagos finches served as one of Darwin’s centerpiece examples of his famed theory of evolution through natural selection, epitomized in “On The Origin of Species.” Those 15 birds (which are actually not finches, but tanagers), each with their very distinct beaks, clearly showed how a group of related birds on a small island chain could have evolved over time to best adapt to their own specific microenvironments.
For example, the large ground finch’s thick, short beak is ideal for cracking open nuts; on the other hand, a subspecies of the sharp-beaked ground finch, with its small, slender bill, is ideal for, well, stabbing other birds and drinking their blood.
Unsurprisingly, this bloodthirsty bird has been given the nickname “vampire finch.” Chiefly, it feeds on boobies – yes, the birds – especially the Nazca and blue-footed boobies. Weirdly, the boobies do not appear to protest too much, offering minimal resistance to this. It is thought that these finches used to clean parasites from the plumage of these birds, and at some point they gained an acquired taste for blood.
3. Torpedo Snails
The Cancellaria cooperii’s shell. Wikimedia Commons, CC BY-SA 3.0
Torpedo snails, known more innocuously as Cooper’s nutmeg, are medium-sized sea snails that prey on the Pacific electric ray, which belongs in the family Torpedinidae.
These parasitic snails are horrifically inventive when it comes to drawing blood from a host. It tracks down its prey by following its distinct chemical trail. After making small cuts on the surface of the ray, it inserts its proboscis – its feeding tube – into the wound. If it can’t get any blood from the ray’s surface skin, it forces its proboscis into the mouth, gill slits or anus instead.
Yikes. At least you could outrun these vampires.
4. Vampire Bats
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Classic vampires, so to speak. Most of the more modern mythology surrounding the nocturnal, hematophagous feeders mentions that vampires can change from human form into bat form in an instant. Although these real-life bats can’t transmogrify into humanoid figures, they are certainly expert blood suckers. There are three bat species that exclusively feed in this way: the common vampire bat, the hairy-legged vampire bat, and the white-winged vampire bat, each with their own specialties.
All three of these bats have front fangs evolved to sever and slice into tough skin. The section of a vampire bat’s brain that processes sound is highly advanced, allowing each to pick up on the regular breathing sounds of sleeping prey, which can include humans on occasion. They hunt almost exclusively at night across a range of environments, using echolocation to build up a “sound map” of their hunting grounds – which range from tropic forests and humid caves to more arid regions. The exception to this is the hairy-legged variant, which has good eyesight but poor echolocation abilities.
Although all vampire bats have the ability to pick up on spikes in thermal radiation generated by their prey, the common vampire bat is even more specialized: It has receptors on its nose that can very precisely sense thermal changes inside the prey itself. These “thermoreceptors” allow it to locate the areas of the prey’s skin where blood is flowing particularly close to the surface. This ability is associated with a section of the common vampire’s brain that resembles the infrared receptor of snakes that can “see” the world around them as heat signatures.
A couple of vampire bats, hanging out. Image credit: belizar/Shutterstock
Contrary to the legends, these vampires don’t go for the necks of humans when they get the rare chance: They’re more likely to go for your big toe – a handy protrusion with a considerable blood flow – as you sleep. As their saliva prevents your blood from clotting (anticoagulant) and stops you feeling the pain of the bite (antiseptic), they drink up while leaving you snoozing away in peace.
To end on a positive note about these vampires after all this somewhat bad press: Their saliva is such a powerful anticoagulant that it is being developed into a drug called “draculin,” which may one day be used to treat heart attacks and strokes by thinning the blood.
