Crab blood could save your life. And they have already done so. Horseshoe crabs are marine anthropods that live in the muddy bottoms of shallow ocean waters. Unlike vertebrates, horseshoe crabs do not have hemoglobin in their blood. Instead, they use hemocyanin to carry oxygen, giving their blood a light blue color.
This blue blood is worth $15,000 a quart. The high price tag is in part due to the extensive harvesting process require to obtain the blood. In addition, only 5 companies are licensed by the FDA and are able produce and sell horseshoe crab’s blood.
A clotting agent in the crab’s blood, known as Limulus Amoebocyte Lysate (LAL), is a powerful tool used by the biomedicine industry to detect presence of endotoxins, a pyrogenic substance that evoke fever or hemorrhagic stroke in people, in medical intravenous fluids, injectable drugs, and supplies.
Pharmaceutical industries tap into LAL’s endotoxin binding and clotting ability. Today, LAL has become the worldwide standard screening test for bacterial contamination.
A sample from the commercial product is taken and mixed with LAL. If endotoxins are present, a firm gel will form. If that tested sample is found to contain an amount of gel that exceeds the limit set by the FDA, the sample fails and the product is rejected.
How is LAL collected? To obtain LAL, the blood of horseshoe crabs is harvested. Harvesting means collecting the crabs from their natural habitat and bleeding them. During the bleeding process, up to 1/3 of the crabs’ blood is removed. Then the crabs are released.
Although horseshoe crabs’ blood can be extracted without killing them, there is some question of how harmful bleeding is to the animals. The LAL industry claims that bleeding have no long-term injury on the animals. Research has shown that once returned to the water, the horseshoe crabs’ volume rebounds in about a week. The LAL manufacturers measured crabs’ mortality rates to be less than 3%. However, two recent studies estimate between 10 -30%.
In addition, another recent report from Plymouth State University and the University of New Hampshire showed that donor crabs are impaired after release and often incapable of mating, and thus threatening the population. Reports of horseshoe crab numbers have also show that the crab’s population is declining. The impact of this decline on pharmaceutical and medical device industries still remains unseen. However, we know that without horseshoe crabs and their incredible blood, we would not be as protected from bacterial contamination as we are today.
Researches from the Wetlands Institute have been underway to search for ways to reduce the strain on the crab’s population. Others are searching for synthetic substitute for LAL. These are all examples of ways that people are trying to give back to this life-saving species. They recognize that the horseshoe crab population is important not only to the biomedical community, but it also has a relationship with other creatures, including us. Ensuring its sustainable population will lead to a safer future for many of us.