When vampire bats stick their tongues into a wound, they don’t just suck the blood. They also introduce their saliva there, and this liquid is composed of other amazing invisible adaptations: indeed, vampire bats are venomous.
This information may seem strange. We generally think of venom as a chemical that an animal introduces into the body of its victim to cause pain or death. But the definition given by biologists is broader: it is a secretion produced in a specialized gland of an animal, and which is transmitted to another animal through a wound in order to disturb its physiology. .
Snake venom, the one we know best, can disrupt the physiology so much that it can cause the death of the victim, and this in several ways: for example, by blocking neurons, or by rotting tissues. However, other animals that do not aim to kill their victims also produce venom. Vampire bats, for example, do not seek to eat the whole cow. They just want to take a sip.
Unfortunately, drinking blood has a few downsides. Vertebrates are equipped with many molecules and cells intended to seal wounds. As soon as these detect the slightest tear in a blood vessel, they begin to make clots to stem the flow.
Vampire bats therefore use venom to promote blood circulation. In an article published in 2013, titled Dracula’s Children: Molecular Evolution of Vampire Bat Venoman international team of scientists analyzed the molecules used by vampire bats to bypass blood defenses.
What is most striking about vampire bat venom is that it attacks the victim’s body in many distinct ways. Blood clots form through a series of reactions involving a chain of enzymes. Vampire bats produce different proteins to attack different enzymes in this chain. Blood platelets, which are fragments of cells, also clump together around wounds to help heal them. Vampire bats make distinct compounds which then attack the platelets.
To make their venom, vampire bats reuse old molecules and give them new roles. When a vertebrate forms a blood clot to close a wound, it must break down that clot once the wound has healed. An enzyme called tissue plasminogen activator creates a store of molecules called plasminogen, which dissolve clots. Vampire bats produce activators to carry out this process in their own blood, but they also produce extra in their mouth glands. Thus, when these tissue plasminogen activators enter a wound during the attack, they allow the victim’s plasminogen to be used directly to promote blood circulation.
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