June 13, 2023 — Horseshoe crabs used to be everywhere. Millions of years before dinosaurs roamed the planet, each spring, the hard-shelled creatures gathered to mate in massive mounds along the beaches of the Atlantic coast. Later, migratory shorebirds like the robin-size red knot learned to fly up from South America to join them for a feast. The crabs’ eggs gave the birds the energy they needed to keep flying north to breed in the Arctic.
But humans began to want something from the crabs, too — their blood. In the 1960s, scientists discovered that the sky blue blood inside horseshoe crabs would clot when it detected bacterial toxins. Vaccines, drugs and medical devices have to be sterile before they’re put inside people. A better toxin-detection system meant less contamination risk for patients, so fishermen soon started collecting and selling the prehistoric animals to be bled.
A synthetic alternative was later invented and has since been approved in Europe as an equivalent to the ingredient that requires horseshoe crabs. But in the U.S., the blood harvest isn’t shrinking. It’s growing. Five companies along the East Coast — with operations in South Carolina, New Jersey, Massachusetts, Virginia and Maryland — drained over 700,000 crabs in 2021. That’s more than any other year since officials started keeping track in 2004. Since then, the number of crabs bled by the industry has more than doubled. At least 80 million tests are performed each year around the world using the blood-derived ingredient.