Chances are you owe your life to the horseshoe crab. In the 1950s, scientists discovered that LAL (Limulus amoebocyte lysate), a clotting agent found in the critter's powder-blue blood, binds to fungi and endotoxins, coagulating into a thick gel around such invaders. The result: a simple, surefire way to detect impurities in pharmaceutical drugs and medical supplies. Here's how drug developer Charles River, one of five companies licensed by the FDA to produce and sell LAL, harvests crabs and turns their blood into tests that can detect bacteria and other contaminants at less than one part per trillion—without killing the creatures.
Photo: Andrew Tingle