Horseshoe crabs are harvested by the millions annually for biomedical bleeding, with their welfare and population linked directly to the survival of migratory shorebirds that depend on crab eggs for fuel.
Horseshoe crabs exposed to the biomedical bleeding process experience capture, transport, and the physical stress of being bled of 30% of their blood volume. Whether horseshoe crabs experience pain in a morally significant sense is uncertain given their primitive nervous system, but the physiological stress of blood removal weakens them and some die. The indirect welfare impact is clearer: declining horseshoe crab populations remove the food source that red knot shorebirds depend on for their migration - birds that starve on migration routes stripped of crab eggs. The availability of synthetic alternatives to horseshoe crab bleeding that protect both crabs and shorebirds makes continued reliance on wild harvest an avoidable welfare and conservation problem.