In case you missed the drum beat of news reports, warnings from pediatricians, and signs at your local pharmacy: flu season is coming! While getting a flu shot (or enduring the flu itself) is a far cry from visiting the seashore, there’s an interesting scientific connection: the blood of Atlantic horseshoe crabs (Limulus polyphemus), which are found in coastal waters from Mexico to Maine, contains a key ingredient in the production of flu shots and other vaccines.
Horseshoe crabs’ white blood cells contain a compound called Limulus Amebocyte Lysate (LAL for short). LAL, researchers have discovered, is what makes the animals’ blood clot when it’s exposed to endotoxins–toxic substances found in the cell walls of certain bacteria, like salmonella, that are released when the bacteria break down. Endotoxins can cause fever, illness, and even death in humans, and, since they’re not living bacteria, normal sterilization does not get rid of them. That’s why biomedical companies have been harvesting LAL from horseshoe crabs since the 1970s and using it to test vaccines, implantable devices, and other medical equipment for the presence of endotoxins.
Our video of the week, a clip from PBS Nature, shows the incredible process by which horseshoe crabs are caught, taken to a laboratory, bled of up to 30 percent of their blue-colored blood, and then released back into the wild.
Read about the horseshoe crab’s fascinating life, how it’s closely intertwined with other species, and how horseshoe crab populations may be threatened in the New Hampshire Wildlife Journal.
Learn more about how researchers discovered LAL and how it is used in the medical industry on the Maryland Department of Natural Resources website.
Find out everything you ever wanted to know about the influenza virus, symptoms of the flu, and how to reduce your risk on the Centers for Disease Control and Prevention’s flu website.
Written by Christine Hoekenga
Christine is a freelance writer, editor, and content strategist, specializing in science and nature. She holds an Bachelor's degree in Environmental Science and Media Studies and a Master's of Science Writing. She has been working in science communication and education for nearly a decade as a journalist, an organizer for conservation groups, and a museum educator. Before joining the Visionlearning team, she served as the New Media and Online Community Manager for the Webby award-winning Smithsonian Ocean Portal. Christine is assisting Visionlearning with developing new modules and glossary terms, managing the blog, and outreach through social media.