Horseshoe crabs are captured and bled to produce limulus amebocyte lysate (LAL) used in medical safety testing, causing mortality and welfare concerns in wild populations.
Horseshoe crabs captured for bleeding are transported, physically restrained, punctured to extract large volumes of blood, and then returned to the sea — or not, as some die in the process. The welfare implications of a procedure that kills up to 30% of individuals are significant, especially for an ecologically important species. The availability of synthetic rFC means that horseshoe crab bleeding is no longer necessary, making continued use difficult to justify on welfare or conservation grounds.