Horseshoe crab blood is vital for testing intravenous drugs, but new synthetic alternatives could mean pharma won't bleed this unique species dry

If you have ever gotten a vaccine or received an intravenous drug and did not come down with a potentially life-threatening fever, you can thank a horseshoe crab (Limulus polyphemus). Horseshoe crab blood is used to produce a substance called limulus amebocyte lysate, or LAL, which scientists use to test for toxic substances called endotoxins in intravenous drugs. Identifying LAL as a highly sensitive detector of endotoxins was a 20th-century medical safety breakthrough.