Horseshoe crabs are harvested by the millions for their blood, used to test medical equipment for bacterial contamination, raising serious conservation and welfare concerns.
The welfare impacts of horseshoe crab bleeding — including dehydration, haemolymph loss and exposure to temperature extremes — are significant and often fatal. A synthetic alternative (recombinant factor C) exists and has been validated as equivalent, but regulatory inertia has slowed adoption. The harvesting of horseshoe crabs also reduces the food supply for critically endangered shorebirds.