Book excerpt: Traveling from the Delaware Bay to the Florida Panhandle, this examination is a quest through the natural history and science behind one of nature's oldest and oddest survivors--the horseshoe crab. With ten eyes, five pairs of walking legs, a heart half the length of their bodies, and blood that can save a person's life, horseshoe crabs have been on this planet for 445 million years--since long before the dinosaurs arrived. This book explores their unique biology and sex life, explains their importance to medical science and migratory shorebirds, and introduces readers to the people who are working to study and protect them.