The horseshoe crab has protected our health for decades. Now it's time to return the favor.

For half a century, the blue blood of the horseshoe crab has protected medical advances by enabling endotoxin tests used in vaccines, drugs, and devices. In the United States, fishermen harvest about 1.5 million horseshoe crabs annually, with two-thirds bled for endotoxin testing and the rest sold for bait. Massachusetts hosts two of the world’s largest producers of the crab blood assay. Roughly 40% of the about 340,000 crabs caught and bled in the state are killed afterward for bait, while the remainder are returned to the ocean after blood loss that can dull their tidal behavior. The eggs support coastal ecosystems by feeding small fish and fueling shorebird migrations, including the red knot, which is listed as threatened. Demand for endotoxin testing is projected to rise 25% by 2030.

Massachusetts, home to major producers, faces ecological costs as the industry grows and lauds the need for a transition away from crab blood toward synthetic alternatives, which are increasingly available. The community is evaluating policy steps to hasten this shift, balancing health protections with crab conservation. The broader scientific and regulatory response highlights how a long-standing medical tool now intersects with wildlife protection and sustainability goals.