Horseshoe crabs have blue blood that contains a special substance that clots around bacteria to prevent infection from spreading. Called LAL for short, it is used to test medical equipment for bacterial contamination. If you’ve ever had a shot, stitches, or surgery, you can thank horseshoe crabs for helping to keep you safe!
Horseshoe crab blood sells for up to $15,000 a quart! Every year, more than 500,000 horseshoe crabs are captured off the East Coast of the U.S. The creatures are brought aboard special ships, where biomedical companies extract some of their blood and release these ten-legged “blood donors” back into the ocean. Watch this process in this clip from PBS’s Crash: A Tale of Two Species.
Most horseshoe crabs survive the blood donation, but scientists recently discovered that extracting their blood may disorient them and make the females less likely to mate.
Humans aren’t the only animals that depend on horseshoe crabs. Shorebirds such as the robin-sized red knot redknots rely on horseshoe crab eggs to fuel their spring migration from South America to their breeding grounds in the Arctic. For more on these amazing birds, check out the award-winning Moonbird by Phillip Hoose, a great classroom resource.
Scientists are hoping to crack the secrets of LAL to make a synthetic version of this life-saving compound. That would end the harvesting of horseshoe crab blood–good news for these ancient creatures. In the meantime, people are working to protect these gentle life-saving creatures by conserving habitat and other activities. Check out horseshoecrab.org to find out how you can help and download free resources for your classroom, including International Horseshoe Crab Jeopardy!
P.S. Horseshoe crabs aren’t crabs at all! They’re more closely related to spiders and scorpions! Learn more about these amazing ancient animals in my new nonfiction kids’ book Extreme Survivors: Animals That Time Forgot.