In a new study, researchers analyzed the DNA and microbiome of three species of vampire bat, the only obligate blood-eating mammals (aka sanguivores) in the world. Their results revealed that gut bacteria are key to the bats' ability to survive on the vital red liquid. (See "The Vampires That Feed on Vampires.")

It seems that these gut critters evolved to help the bats live on blood meals, says study leader Marie Lisandra Zepeda Mendoza, a geneticist at the University of Copenhagen. The "holistic" study, which examined both the microbiota and the bat's DNA, is among the first of its kind to investigate how vampire bats digest blood, Mendoza says by email.

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