🤪 Fun & Weirdpublished 2w ago
Horseshoe crabs bleed bright blue to detect bacterial toxins
Horseshoe crabs have royal blue blood because oxygen is carried by copper-rich hemocyanin instead of iron-rich hemoglobin. Even stranger is its immune defense: specialized cells called amebocytes clot instantly when exposed to bacterial endotoxins, entrapping microbes in a thick gel. Because of this hypersensitivity, biomedical facilities harvest their blood to produce Limulus amebocyte lysate, a critical testing agent used globally to ensure vaccines, IV drips, and medical implants are free from contamination.
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