Tom Gilbert, a geneticist at the University of Copenhagen, has found that leeches are a great way to track down rare creatures. He was inspired after a colleague monitoring rare tapirs in Malaysia was bitten by a terrestrial leech (a common annoyance in tropical rainforests) and wondered whether the blood inside it could be used for DNA analysis. Gilbert tested the idea by feeding 40 leeches goat blood. After he ground them into a paste, he found that every one contained goat DNA, even four months after its last meal. In 2010, Gilbert tried the method on 25 leeches that had been collected in Vietnam. "We kind of hit the jackpot," he says. Twenty-one leeches contained DNA from mammals, two of which were extremely rare. Although there was no evidence of the saola, Gilbert did find DNA from the Annamite striped rabbit. (Scientists first discovered the animal in a Laotian food market in 1995 but have hardly seen it since.) Gilbert is now analyzing the recent meals of leeches collected in countries including Indonesia, Malaysia, and Madagascar.