Spider webs contain information about the species living around them. (Photo: Iurie Nistor, via Wikimedia Commons.)

Have you ever touched a spider web? The spider adds a sticky glue to the web to trap its food. But that’s not all it catches. Scientists have learned that the sticky strands trap environmental DNA (eDNA).

What is eDNA? It’s the tiny bits of DNA living things leave behind. Skin cells, bits of hair, scales – even poop. It’s found in water, soil, and floating in the air.