Horseshoe crabs are harvested by the millions for their blue copper-based blood used in pharmaceutical testing, raising welfare concerns about a species that has existed for 450 million years.
Whether horseshoe crabs have welfare-relevant experiences is scientifically uncertain given their distant evolutionary relationship to vertebrates. However, the scale of their harvest for biomedical purposes — hundreds of thousands annually with significant mortality — warrants serious consideration. The availability of a validated synthetic alternative (rFC) that does not require live animals makes continued reliance on crab blood increasingly difficult to justify. From a precautionary welfare perspective, transitioning the pharmaceutical industry to rFC would eliminate the welfare risk entirely while also protecting a remarkable and ecologically important species.