It’s always used as a specific fact for horseshoe crabs but hemocyanin is very common in the hemolymph/circulatory systems of mollusks and arthropods. Most regular crabs, squid and octopus, clams, spiders, and shrimp. They just don’t make good blood farms like horseshoe crabs do and don’t have Limulus Amebocyte Lysate.
It’s always used as a specific fact for horseshoe crabs but hemocyanin is very common in the hemolymph/circulatory systems of mollusks and arthropods. Most regular crabs, squid and octopus, clams, spiders, and shrimp. They just don’t make good blood farms like horseshoe crabs do and don’t have Limulus Amebocyte Lysate.