Horseshoe Crab Blood

Thanks to a natural immuno-response in horseshoe crab blood, biologists have been able to test medicine and healthcare equipment for contamination since 1958.

Living Fossils

Having walked this Earth for over 300 million years, horseshoe crabs are considered living fossils. They’ve been around for so long, they actually predate the first dinosaurs by about 100 million years.

During their history, they’ve evolved very little, and it’s theorized that their close ancestors could be even older.

Strange Biology

Due to the way horseshoe crabs shed their skin, they must regrow two of their four eyes every time they molt. Possessing no teeth, the horseshoe crab must also break its food apart with its legs before shoving it straight into its open mouth.

While it may have crab in its name, the horseshoe crab is not a crustacean, but an arachnomorph. They are more related to spiders than crabs!

Blue Blood

Their circulatory system is completely open, meaning their blood doesn’t pass through veins or capillaries but circulates around the entire cavity of their body. Horseshoe crabs don’t have white blood cells to fight off infection. Instead, their blood is able to detect toxins and bacteria, and then form a robust gel casing around anything harmful.

While most animal blood is red due to a reliance on iron, horseshoe crab’s is rich with copper, making it blue. By 1958, scientists developed a way to use their blood to validate the purity of medicine and equipment. Prior to this, infections caused by attempts at medical care were sometimes worse than the injury itself.

horseshoe crab blood