Though she be but little, she is fierce! At half a millimeter long—about the width of a human hair—bdelloid rotifers might be easy to miss. But these tiny freshwater critters are some of the toughest animals on the planet. Comprised entirely of females, they’re particularly notorious for “stealing” genes from other organisms. That ability has allowed them to go 40 million years without sex. New research may explain how this little animal got to where it is today. According to a new study, some b