If you want to protect rare species, first you have to find them. In the past few years, biologists have developed a powerful new tool to do that. They’ve discovered that they can often find traces of animal DNA in streams, ponds — even oceans.

Biologists usually look for the hellbender (nicknamed the “snot otter”) by prying up enormous stream boulders and snorkeling under them.

“We can actually extract the DNA from this water sample and be able to tell that it’s hellbender DNA. And we know that a hellbender is there without ever having to lift a rock, or maybe even see one,” [said scientist Stephen Spear].

Via NPR.