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Horseshoe crab blood can detect and trap bacterial toxins, saving human lives.

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The bright blue blood is crucial for human health but the biomedical industry needs to keep the population steady

The helmet-shaped creature has developed a unique defense to compensate for its vulnerability to infection in shallow waters. When faced with toxins produced by bacteria, amebocyte cells in the blood -- colored blue by their copper-based molecules -- identify and congeal around the invading matter, trapping the threat inside a gel-like seal that prevents it from spreading.

Nature's method is now utilized on a grand scale. Over 600,000 crabs are captured each year during the spring mating season, to "donate" around 30% of their blood in a handful of specialist facilities in the United States and Asia. The blood is worth $60,000 a gallon in a global industry valued at $50 million a year.

An extract has been used in the industry-standard limulus amebocyte lysate (LAL) contamination test since the 1970s -- replacing a rabbit-based system. Forty-five minutes of exposure to the crab's blood is enough to reveal endotoxins from gram-negative bacteria which otherwise avoid detection, and is sensitive enough to isolate a threat the equivalent size of a grain of sand in a swimming pool. The U.S. Food and Drug Administration (FDA) requires that intravenous drugs and any medical equipment coming in contact with the body must first pass through the crab's blood, from needles to surgical implants including pacemakers. As a result, thousands more of us survive such procedures.

Too bad they haven't figured out how to make it synthetically yet.

I wonder if horseshoe crabs have an alien abduction narrative in their culture.  :-)

That boat is then brought to shore and the process speeds up as the precious Horseshoe crabs are always returned to the ocean on the same day that they are captured. The crabs are placed inside of a dark, damp, enclosed vehicle and moved to the lab's facility. There, workers remove barnacles, sand and other debris on the shells in order to check for injuries or other obvious ailments. Any injured crabs don't move on to the next step for fear that they will be killed in the process.

Every healthy crab is folded in half at its hinged carapace and strapped to a metal bleeding table. There, a stainless steel needed is pushed into each one, piercing "the pericardium to drain the oxygenated blood that's on its way to the heart," according to Wired. "About 100 milliliters of blood drains into a sterilized bottle."

Once the bleeding is completed, the crabs are released far from where they were caught so that they aren't scooped up and re-bled before they have enough time to regenerate what has already been lost. Work, though, continues in the lab, where the powder-blue blood has to be spun in a centrifuge so that the desired elements can be isolated. The LAL, once siphoned off and bottled, is worth about $15,000 per quart.

Wow, that does sound like alien abduction!

I can see how it's valuable enough for someone to work on a synthetic version.

But I guess scientists are nowhere near that yet. 

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