In addition, it’s best not to keep fiddler crabs in a tank with fish or any other species; they might try to catch the fish ...

This story appears in the August 2016 issue of National Geographic magazine. All around her, guys wave seductively, beckoning her to their beach homes. How will the female fiddler crab pick a mate?

I stood on the muddy banks of the Great Marsh, a salt marsh an hour north of Boston, and pulled a thumb-sized crab with an ...