Historic numbers of animals across the globe have become endangered or pushed to extinction. But some of these species sit in limbo — not definitively extinct yet missing from the scientific record. Rediscovering a "lost" species is not easy. It can require trips to remote areas and canvassing a large area in search of only a handful of animals. But new technology and stronger partnerships with local communities have helped these hidden, "uncharismatic" creatures come to light.

Have other scientific gray areas you want us to cover in a future episode? Email us at shortwave@npr.org!

Spiderwebs can capture environmental DNA, or eDNA, from vertebrate animals in their area, potentially making them a useful tool in animal monitoring, tracking and conservation.