Every Animal Leaves a Genetic Signature Behind
A fish does not need to be caught to be identified. As it swims, it sheds scales, mucus, urine, and faeces, each carrying fragments of its DNA into the surrounding water. The same is true for every aquatic creature: otters, frogs, turtles, even microscopic zooplankton. A cup of river water, properly collected and preserved, holds a floating library of every species that has passed through in the preceding days.
