Vampire bats are one of four mammalian lineages to have developed venom, along with platypus, water shrews and slow lorises. While many reptiles and invertebrates produce venom for the purpose of killing their prey, bats just want the blood to flow more freely so they can gain a lot in a short amount of time.
“The venom has three functions,” says Fry. “It blocks the coagulant cascade in multiple ways, it dilates the small arteries under the skin and it has an anaesthetic effect so the animal being fed on doesn’t shake the bat off.
Fry says his team has yet to identify the anaesthetic molecule. However, in exploring the anticoagulants they learned that the bat uses not only multiple compounds but many slightly different versions of each.
“This means that even if an antibody is generated against one molecule, there are a number of others that will sneak past the prey’s defence system and keep the blood flowing,” Fry says. “This means the same victim can be fed on night after night.”
The three species of vampire bats have differences in their venom to reflect the common vampire bat’s mammalian diet, while the other two species prefer birds. While Fry has compared their venoms, the venoms that are most effective on humans hold the most interest.
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