Welcome to brain Stuff from how Stuff Works. Hey, brain Stuff, Lauren Vogel Bomb. Here. When you look at a horseshoe crab, you're looking at half billion years into the past. These primitive animals were around long before the dinosaurs and survived ice ages and asteroids almost unchanged their cozy ecological Niche necessitated few body modifications, So while horseshoe crabs today are
different than their ancestors, they're not that much different. You're also looking at a creature whose value approaches a half billion dollars a year to the biomedical and commercial fishing industries. The blood of horseshoe crabs is extremely important to science. It's capable of detecting a certain type of bacteria in humans, thereby saving lives. More on that in a moment, but
a bit of biology first. Horseshoe crabs resemble semi circular armored tanks and are an appropriate army green to brown color. Despite their name, they are more closely related to spiders and scorpions than to crab abs. Of the four species of horseshoe crabs around today, Limulus polyphemus is found along North America's eastern coast from Maine to Mexico. The other three species are found in Southeast Asia. Horseshoe crabs can be found in abundance on many beaches near their spawning zones.
They commonly become overturned by the action of waves during spawning and may not be able to write themselves, which leads to death. But not every horseshoe crab you see on the beach is dead. They also molt, leaving behind their old exo skeleton and forming a newer, bigger one. The horseshoe body has three sections. The large head or prosema, houses the brain and heart, and six pairs of appendages
are attached to it. In males, the first pair are hook like and used to clamp onto a female during mating. In the abdomen or opus, those sma muscles control the gills and tail, called the tellson. The tellson serves as a rudder and helps crabs write themselves if they get flipped over during spawning. Females are third bigger than males and can weigh twice as much upwards of ten pounds that's about four and of kilos. It takes about ten years for horseshoe crab to grow to adult size. Spawning
peaks in May and June. At high tide during the full or new moon, the female digs a hollow in the sand beneath her and lays a cluster of several thousand eggs, which are fertilized by the male clinging to her back. Satellite males closely follow the couple for the chance to pass on their jeans to some of the eggs. The female repeats the process several times per night and may spawn for several nights. All told, each breeding female can lay up to a hundred thousand eggs a season.
Delaware Bay has the largest spotting population in the world and as a stop oversight for shorebirds in the Atlantic Flyway, which is the north south path to and from Arctic breeding grounds. Up to a million birds flocked to the site to gorge on horseshoe crab eggs, building their strength for the journey north. But decades of overharvesting crabs as bait to catch welk, eel and conk have decimated their
populations and turned the egg feast into near famine. Hundreds of thousands of crabs are taken every year for bait. Then there's the effect of shoreline development and habitat loss. Beaches, intertidal flats, and deep bay waters are all necessary for crabs survival and reproduction, but are increasingly encroached upon by
construction and poisoned by fertilizer runoff. We spoke via email with John Tannacretti, a professor of earthen environmental sciences at Malloy College and director of the Center for Environmental Research and Coastal Oceans Monitoring. He said we monitored more than a hundred and fifteen sites on Long Island for over seventeen years and found that horseshoe crab habitat has declined
by more than eight percent. A loss of habitat means loss of breeding animals, clearly seen in the long term decline in horseshoe crabs in the area by about one percent per year. Though their health is critically threatened by humans, we benefit enormously from horseshoe crabs. Horseshoes. Copper based blue tinged blood contains a clotting agent called lumulus ambo site ly sate or l A L, which detects endotoxins released by bacteria that can cause fever, stroke, organ damage, and
even death. L A L is used to test drugs, vaccines, and medical devices, and it's so essential to biomedical companies that manufacturing around the world would halt if the supply was cut off. Understandably, L A L is one of the most valuable fluids on Earth, at a price of about fifteen thousand dollars a quart. Horseshoe blood developed this remarkable clotting ability as a response to life in an
oceanic soup of bacteria. When microbes invadim mammal, millions of tiny blood vessels limit their spread and white blood cells bite them off. But not so with horseshoe crabs. Their blood moves freely through their tissues and organs, providing a wide playing field for bacterial infection. But these bacteria and crabs have co evolved for millions of years, and so crabs have defenses to Horseshoe crabs don't have an immune
system exactly. Their single type of blood cell and ambo site, which is a cell that can move around, does all the usual work of blood cells, repairing wounds, gobbling up dead cells, transporting and storing digested material. But these amibo sites also release a substance that clots like wild when they detect a bacterial and a toxin, clots entrap the invading bacteria, limiting further infection. Larger clots can also seal
a wound. Before L A L was discovered, BioMed companies used rabbits to test for endotoxins because rabbit blood also tends to clot in the presence of these toxins. If after injection with the test substance and animal developed signs of infection, which could take up to forty eight hours, the sample was determined to be contaminated and the rabbit
would die. The discovery of L A L has saved countless rabbits from this fatal testing, but in turn, hundreds of thousands of crabs every year participate in an involuntary blood drive to harvest horseshoe crab blood. The unspecting creatures, larger females being preferred, are hauled out of shallow coastal areas and brought to a lab where they're chilled for an hour or so, and then of the crabs blood is drained off. After leading, the animals are returned to
the ocean. The sooner they're returned, the more likely they are to survive, which is important because though this is considered a low mortality catch and release procedure, as many as thirty percent of horseshoe crabs can die from the bleeding process, and because of the demand for L A
L the toll on horseshoe crabs can be huge. Six hundred thousand crabs are harvested every year for BioMed purposes, meaning up to a hundred and eighty thousand crabs may be lost to the procedure every year, and the long term impact may be much worse. In areas where the most crabs are harvested for blood letting, fewer females show
up to spawn. North America's own Limuleus polyphemus was placed on the vulnerable list by the International Union for the Conservation of Nature in and the problem is worse in Asia, where no animals are returned to their habitat. Tan O Creti said in Singapore, during the breeding season, ten thousand adults per day are harvested blood out and then prepared for sale as food. At this rate, they could be extinct. At this rate, they could be extinct there in a decade.
Tennecredi boils down the next steps needed quote. Three things have to happen immediately and consistently, one stop all collection for bait to get FDA approval of synthetic L A L, and three protect crab breeding sites. There has been progress on synthetic L A L. Although an effective L A L substitute has been available for fifteen years, only one facility could produce it, and BioMed companies didn't want to
rely on a single source. But then another facility began production and Eli Lillian Company announced it would phase out natural L A L by in the next few years and phase in synthetic L A L. Good news. Indeed. Today's episode was written by Laura and Fick and produced by Tyler Clang for iHeart Radio's How Stuff Works. For more on this and lots of other continually spawning topics, visit our home planet how stuff Works dot com and
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