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The Blood Harvest - Alexis C. Madrigal - The Atlantic


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The thing about the blood that everyone notices first: It's blue, baby blue. 

The marvelous thing about horseshoe crab blood, though, isn't the color. It's a chemical found only in the amoebocytes of its blood cells that can detect mere traces of bacterial presence and trap them in inescapable clots. 

To take advantage of this biological idiosyncrasy, pharmaceutical companies burst the cells that contain the chemical, called coagulogen. Then, they can use the coagulogen to detect contamination in any solution that might come into contact with blood. If there are dangerous bacterial endotoxins in the liquid—even at a concentration of one part per trillion—the horseshoe crab blood extract will go to work, turning the solution into what scientist Fred Bang, who co-discovered the substance, called a "gel."

"This gel immobilized the bacteria but did not kill them," Bang wrote in the 1956 paper announcing the substance. "The gel or clot was stable and tough and remained so for several weeks at room temperature."

If there is no bacterial contamination, then the coagulation does not occur, and the solution can be considered free of bacteria. It's a simple, nearly instantaneous test that goes by the name of the LAL, or Limulus amebocyte lysate, test (after the species name of the crab, Limulus polyphemus).

So, now, the horseshoe blood test is a big business. "Every drug certified by the FDA must be tested using LAL," PBS's Nature documentary noted, "as do surgical implants such as pacemakers and prosthetic devices." 

I don't know about you, but the idea that every single person in America who has ever had an injection has been protected because we harvest the blood of a forgettable sea creature with a hidden chemical superpower makes me feel a little bit crazy. This scenario is not even sci-fi, it's postmodern technology. 

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Horseshoe crabs are an ancient animal, more than half a billion years old. They have their own ways of doing things, a fact we've been exploiting for decades. Their blue blood? That's because copper plays the role in the crabs' blood that iron does in ours. The iron-based, oxygen-carrying hemoglobin molecules in our blood give it that red color; the copper-based, oxygen-carrying hemocyanin molecules in theirs make it baby blue. 

Our own species evolved a thousand times more recently, coming into our current anatomical form a couple hundred thousand years ago. Let's hope we don't wipe horseshoe crabs out after we finish cloning their ancient chemical wisdom. 

Is there a risk of extinction from human for those crabs? I'm pretty sure all this crabs are breed, not taken wild, it would be too expansive for the companies.

They are taken wild and then released:

<First, a team of fishermen captures hundreds of the crabs when they come near the beaches of South Carolina to spawn. They're not very fast and they don't see the danger coming, so the fishermen, who are licensed by the Department of Natural Resources, can just wade around in the shallow waters picking them up and dumping them into a boat floating nearby.

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.>

Extinction could occur from other environmental impacts, like pollution or other changes to their environment.

More, from Wikipedia

Horseshoe crab are used as bait to fish for eels (mostly in the United States) and whelk. However, fishing horseshoe crab is temporarily forbidden in New Jersey (moratorium on harvesting) and restricted to only males in Delaware. A permanent moratorium is in effect in South Carolina.[14]

A low horseshoe crab population in Delaware Bay is hypothesized to endanger the future of the red knot. Red knots, long-distance migratory shorebirds, feed on the protein-rich eggs during their stopovers on the beaches of New Jersey and Delaware.[15] An effort is ongoing to develop adaptive-management plans to regulate horseshoe crab harvests in the bay in a way that protects migrating shorebirds.

So apparently it's less expensive to take them wild than breed them. Interesting.

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