Sustainability of Horseshoe Crab Blood Harvesting

By living in the Greenbelt, my peers and I have been able to look into the products we use in our everyday lives and examine how sustainable these products are and what impact they may have on our environment. While doing research, I came across an issue that has been affecting my hometown of Charleston, South Carolina, the unsustainable practice of horseshoe crab blood harvesting.

The horseshoe crab is a mysterious species, even older than dinosaurs, resulting in them having many unique traits that make them scientifically special (Center for Biology and Diversity). Horseshoe crabs have unique blue blood due to their high copper levels (Animal Welfare Institute). Scientists have found that this agent allows for agglutination, or clotting, when there are endotoxins present. This process is similar to how the blood on the outside of your body hardens if you get a cut; however, in horseshoe crabs, this occurs in the presence of gram-negative bacteria. By taking the blood of horseshoe crabs, scientists are able to test if humans or animals are infected with endotoxins. This process is also used to test any equipment that enters the body of a human or animal. This includes needles used for vaccines, insulin, and replacement joints. The horseshoe crab blood makes sure these materials are truly sterile and do not infect the patient.

While this practice has a profound impact on the medical field, it is also affecting the populations of the horseshoe crabs. The actual process of extracting blood from the crabs does not kill them; however, due to stressful situations and improper care of the horseshoe crabs, 10-30% of them die in the process (Animal Welfare Institute). Many migratory shorebirds like the robin-size red knot depend on the eggs of horseshoe crabs to feed on (NPR). With the dwindling population of the horseshoe crabs, some species of shorebirds are now labeled as vulnerable or endangered as a result. The suspicion that they cannot effectively spawn eggs after a large amount of blood has been extracted has become a prevalent issue (Scientific American). 

Additionally, many sources have shown that the individuals collecting the horseshoe crabs are not complying with state laws to handle them carefully. It’s vital for horseshoe crabs to have their tail to live; however, many of the fishermen collecting the crabs have admitted to holding on to the tails and even breaking them to make it easier to carry and transport the crabs. (NPR) Additional footage has even been taken from Turtle Island, SC, of fisherman grabbing the horseshoe crabs by their tail like spurs and loading hundreds onto small johnboats. In 2021, a record number of 700,000 horseshoe crabs were bled for the roughly 80 million tests (NPR). In addition to the damage to their tails, crabs are also forced to spend anywhere from 24-72 hours out of the ocean, which for aquatic animals is very stressful and leads to the death of many of these crabs (Scientific American). The death toll of these creatures is rising, and as a result, Asian tri-spine horseshoe crabs are now listed as endangered, and the American horseshoe crab is to be listed as vulnerable by the IUCN Red List of Threatened Species (Gene Drive Network).

 

Blood Money: Vested Industry Interests Keep Drain Open on Horseshoe Crab Population | Animal Welfare Institute, awionline.org/awi-quarterly/winter-2021/blood-money-vested-industry-interests-keep-drain-open-horseshoe-crab. Accessed 7 Nov. 2025.