What Do Earwigs Do With Those Pincers Anyway? | Deep Look

Thanks to CuriosityStream for supporting PBS Digital Studios. Go down by the shoreline, turn over a rock, and you're likely to find this. A maritime earwig. Now don't get stuck on their name. Earwigs are not interested in your ear. Really, they just want to hide out and hunt tiny prey like these sandhoppers. They're cousins to the common European earwig you might find in your backyard. Both earwigs wield fearsome-looking pincers on their rear. But why keep them on their backside when most animals bear their weapons up front? For one thing, earwigs spend the majority of their lives underground. So it's a lot easier to drag those massive pincers than to push them. Scientists call the pincers cerci. They may look like jaws, but they're actually modified legs. You can find them on the earwig's distant relatives too, like cockroaches and crickets. Male earwigs have curved pincers. On females, they're straight. They use them to hunt, to defend themselves from predators, and to brawl. When one male meets another, they size each other up. If they're evenly matched, it's on. Using their pincers, they go straight for each other's abdomens. It's rarely a duel to the death. It's more of a wrestling match. Usually the bigger one with bigger pincers sends his opponent running. The loser scurries off and sulks. But size isn't everything. Check out this guy's pincers. They're pretty symmetric, but this other one's aren't. See how one end curves around the other? They're lopsided. Researchers at San Francisco State University wanted to know if that asymmetry might give some earwigs a competitive advantage. So they staged matches between males to see if the shape of those pincers made a difference. And it did. When evenly sized earwigs battled, those with more asymmetric pincers won more often. And winning could mean more territory, more food, and more access to females. Scientists at Villanova University wanted to know if that asymmetry came at a cost. Now, in most animals, symmetry is a sign of health. It makes them more attractive to potential mates. That's why it's pretty rare to find asymmetry in nature. But earwigs aren't so superficial. The asymmetry that helps the males fight doesn't make them less attractive to mates. Turns out females don't care if a guy's pincers might be a little crooked. CuriosityStream is a subscription streaming service that offers documentaries and non-fiction titles from a variety of filmmakers, including CuriosityStream Originals. You can learn more at curiositystream.com slash deeplook, and use the code deeplook during the sign-up process. So what about female earwigs? They don't go looking for a fight, but they will use their pincers to defend their eggs, mostly from other hungry females. If you like Deep Look, crawl out from under that rock and subscribe. See you next time.