Horseshoe crabs predate dinosaurs by more than 100 million years. They’ve also saved more than a million human lives thanks to a substance in their blood that the medical industry uses to fight infections! Find out why the horseshoe crab population has been in a downward spiral since the mid-1990s, and what’s being done to save them. William R. Hall is a marine researcher at University of Delaware, which runs a horseshoe crab education website.
