The horseshoe crab has been around since prehistoric days, but some experts are now worried the biomedical industry is bleeding them dry—literally. In her story for Popular Mechanics, Caren Chesler explores how retrieving the blue blood of the marine invertebrate has become a lucrative and essential industry, thanks to a clotting agent found in that blood. The agent is used to make limulus amoebocyte lysate, a substance that can spot Gram-negative bacteria like E. coli by morphing from a liquid to a clotted gel when it encounters an endotoxin in the bacteria. It's the only such test that has the FDA's OK, and it's used to make sure the bacteria isn't present in and on everything from vaccines to scalpels. The crabs are pulled out of the water, trucked to a biomedical lab where they're drained of about a third of their blood, then thrown back in the sea.
But post-depletion follow-up on the crabs has been limited, meaning no one really knows how they do once they're back in the water after their rigorous ordeal. More than half a million crabs are bled annually, with one estimate saying the liquid can command $14,000 a quart (some experts say that figure may be high). With the Americas' medical device industry expected to grow 25% or so over the next few years, the demand for the horseshoe crab's blood isn't likely to diminish. "Every man, woman, and child, and domestic animal on this planet that uses medical services is connected to the horseshoe crab," a conservationist tells Chesler—meaning bad news if the species moves from the "vulnerable" column, the level it was raised to last year, to the "endangered" one. Read Chesler's full piece, which follows the work of two scientists tracking bled crabs. (Read more Longform stories.)