All along the shoreline, slick shells of horseshoe crabs glisten in the fading daylight. If you listen closely, and you can hear their subtle clacking and the whisper of water over their carapaces. It’s horseshoe crab spawning season in Delaware Bay. Every May and June, on nights when the moon is new and the tide is high, they crawl onto the beach to mate and bury their eggs. The ritual goes back 445 million years. They are bizarre creatures with 10 eyes that offer insights into how vision evolved. And their blood has saved countless human lives — including yours.
What has 10 eyes, legs that chew, and blood that can save your life?
