Millions of unseen species fill Earth

This undated photo provided by Penn State University Biology Prof. Blair Hedges shows a threadsnake, the smallest snake species currently known to exist, curled up on a quarter. The tiny snake, found in Barbados, is approximately 1000 mm long, lays one single long egg, and is the shortest of 3,000 species of snakes. Scientists now think there may be 8.8 million species on Earth, but nearly 7 million of them haven’t been discovered yet because they’re too small and hard to find. This threadsnake found as a new species in 2008 by Penn State University professor Blair Hedges in Barbados. It’s the shortest snake in the world, measuring only four inches long. (AP Photo/Penn State University, Blair Hedge)

Our world is a much wilder place than it looks. A new study estimates that Earth has almost 8.8 million species, but we've only discovered about a quarter of them. And some of the yet-to-be-seen ones could be in our own backyards, scientists say. (AP)