Science and nature are strange sometimes. Take horseshoe crabs, for example. They look like helmets with long prickly tails scurrying along the sea floor.

On the inside, they are just as unusual. Bright, milky, blue blood flows in their bodies. That sounds like science fiction—not fact!

Believe it or not, that unusual blue blood is critical for medical progress. It’s the only natural resource in the United States that is used to make sure injectable medicine isn’t contaminated. Clean needles depend on the blue blood of horseshoe crabs.  

Every year, thousands of horseshoe crabs arrive in laboratories. Scientists safely collect their blue blood. They take just enough blood so that the crabs aren’t hurt. Then the crabs go back home to the ocean. Many of the crabs come from the coast of South Carolina.

What makes horseshoe crab blood blue? And why does that matter? The blood is blue because it has copper in it. It is also filled with valuable proteins. Scientists use those proteins to check medical products for bacteria.

Back in the 1950s, scientists discovered that horseshoe crabs have a strong immune system. That means their blood is really good at fighting off bacteria. Scientists used the blue blood to develop the LAL test. That test makes sure medical materials and supplies are free of bacteria. Horseshoe crabs are the only domestic source of the LAL test’s key ingredient.

Foster Jordan is senior vice president of Charles River. That company tests most of the world’s medical devices. The company uses crab blood to make sure things like IV bags, dialysis solutions, and even surgical cleaning wipes are safe to use. “If it touches your blood, it’s been tested by LAL. And, more than likely, it’s been tested by us,” says Mr. Jordan.

Synthetic (man-made) alternatives aren’t widely accepted by the healthcare industry. That’s why scientists depend on crabs for medical supply cleanliness. 

Why? God cares for our lives. He provided horseshoe crab blood to use in medicine.