WEBVTT - Why is Horseshoe Crab Blood So Expensive?

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<v Speaker 1>Welcome to brain Stuff from how Stuff Works. Hey, brain Stuff,

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<v Speaker 1>Lauren Vogel Bomb. Here. When you look at a horseshoe crab,

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<v Speaker 1>you're looking at half billion years into the past. These

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<v Speaker 1>primitive animals were around long before the dinosaurs and survived

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<v Speaker 1>ice ages and asteroids almost unchanged their cozy ecological Niche

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<v Speaker 1>necessitated few body modifications, So while horseshoe crabs today are

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<v Speaker 1>different than their ancestors, they're not that much different. You're

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<v Speaker 1>also looking at a creature whose value approaches a half

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<v Speaker 1>billion dollars a year to the biomedical and commercial fishing industries.

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<v Speaker 1>The blood of horseshoe crabs is extremely important to science.

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<v Speaker 1>It's capable of detecting a certain type of bacteria in humans,

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<v Speaker 1>thereby saving lives. More on that in a moment, but

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<v Speaker 1>a bit of biology first. Horseshoe crabs resemble semi circular

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<v Speaker 1>armored tanks and are an appropriate army green to brown color.

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<v Speaker 1>Despite their name, they are more closely related to spiders

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<v Speaker 1>and scorpions than to crab abs. Of the four species

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<v Speaker 1>of horseshoe crabs around today, Limulus polyphemus is found along

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<v Speaker 1>North America's eastern coast from Maine to Mexico. The other

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<v Speaker 1>three species are found in Southeast Asia. Horseshoe crabs can

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<v Speaker 1>be found in abundance on many beaches near their spawning zones.

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<v Speaker 1>They commonly become overturned by the action of waves during

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<v Speaker 1>spawning and may not be able to write themselves, which

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<v Speaker 1>leads to death. But not every horseshoe crab you see

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<v Speaker 1>on the beach is dead. They also molt, leaving behind

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<v Speaker 1>their old exo skeleton and forming a newer, bigger one.

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<v Speaker 1>The horseshoe body has three sections. The large head or prosema,

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<v Speaker 1>houses the brain and heart, and six pairs of appendages

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<v Speaker 1>are attached to it. In males, the first pair are

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<v Speaker 1>hook like and used to clamp onto a female during mating.

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<v Speaker 1>In the abdomen or opus, those sma muscles control the

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<v Speaker 1>gills and tail, called the tellson. The tellson serves as

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<v Speaker 1>a rudder and helps crabs write themselves if they get

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<v Speaker 1>flipped over during spawning. Females are third bigger than males

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<v Speaker 1>and can weigh twice as much upwards of ten pounds

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<v Speaker 1>that's about four and of kilos. It takes about ten

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<v Speaker 1>years for horseshoe crab to grow to adult size. Spawning

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<v Speaker 1>peaks in May and June. At high tide during the

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<v Speaker 1>full or new moon, the female digs a hollow in

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<v Speaker 1>the sand beneath her and lays a cluster of several

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<v Speaker 1>thousand eggs, which are fertilized by the male clinging to

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<v Speaker 1>her back. Satellite males closely follow the couple for the

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<v Speaker 1>chance to pass on their jeans to some of the eggs.

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<v Speaker 1>The female repeats the process several times per night and

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<v Speaker 1>may spawn for several nights. All told, each breeding female

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<v Speaker 1>can lay up to a hundred thousand eggs a season.

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<v Speaker 1>Delaware Bay has the largest spotting population in the world

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<v Speaker 1>and as a stop oversight for shorebirds in the Atlantic Flyway,

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<v Speaker 1>which is the north south path to and from Arctic

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<v Speaker 1>breeding grounds. Up to a million birds flocked to the

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<v Speaker 1>site to gorge on horseshoe crab eggs, building their strength

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<v Speaker 1>for the journey north. But decades of overharvesting crabs as

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<v Speaker 1>bait to catch welk, eel and conk have decimated their

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<v Speaker 1>populations and turned the egg feast into near famine. Hundreds

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<v Speaker 1>of thousands of crabs are taken every year for bait.

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<v Speaker 1>Then there's the effect of shoreline development and habitat loss. Beaches,

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<v Speaker 1>intertidal flats, and deep bay waters are all necessary for

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<v Speaker 1>crabs survival and reproduction, but are increasingly encroached upon by

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<v Speaker 1>construction and poisoned by fertilizer runoff. We spoke via email

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<v Speaker 1>with John Tannacretti, a professor of earthen environmental sciences at

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<v Speaker 1>Malloy College and director of the Center for Environmental Research

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<v Speaker 1>and Coastal Oceans Monitoring. He said we monitored more than

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<v Speaker 1>a hundred and fifteen sites on Long Island for over

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<v Speaker 1>seventeen years and found that horseshoe crab habitat has declined

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<v Speaker 1>by more than eight percent. A loss of habitat means

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<v Speaker 1>loss of breeding animals, clearly seen in the long term

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<v Speaker 1>decline in horseshoe crabs in the area by about one

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<v Speaker 1>percent per year. Though their health is critically threatened by humans,

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<v Speaker 1>we benefit enormously from horseshoe crabs. Horseshoes. Copper based blue

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<v Speaker 1>tinged blood contains a clotting agent called lumulus ambo site

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<v Speaker 1>ly sate or l A L, which detects endotoxins released

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<v Speaker 1>by bacteria that can cause fever, stroke, organ damage, and

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<v Speaker 1>even death. L A L is used to test drugs, vaccines,

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<v Speaker 1>and medical devices, and it's so essential to biomedical companies

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<v Speaker 1>that manufacturing around the world would halt if the supply

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<v Speaker 1>was cut off. Understandably, L A L is one of

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<v Speaker 1>the most valuable fluids on Earth, at a price of

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<v Speaker 1>about fifteen thousand dollars a quart. Horseshoe blood developed this

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<v Speaker 1>remarkable clotting ability as a response to life in an

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<v Speaker 1>oceanic soup of bacteria. When microbes invadim mammal, millions of

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<v Speaker 1>tiny blood vessels limit their spread and white blood cells

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<v Speaker 1>bite them off. But not so with horseshoe crabs. Their

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<v Speaker 1>blood moves freely through their tissues and organs, providing a

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<v Speaker 1>wide playing field for bacterial infection. But these bacteria and

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<v Speaker 1>crabs have co evolved for millions of years, and so

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<v Speaker 1>crabs have defenses to Horseshoe crabs don't have an immune

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<v Speaker 1>system exactly. Their single type of blood cell and ambo site,

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<v Speaker 1>which is a cell that can move around, does all

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<v Speaker 1>the usual work of blood cells, repairing wounds, gobbling up

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<v Speaker 1>dead cells, transporting and storing digested material. But these amibo

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<v Speaker 1>sites also release a substance that clots like wild when

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<v Speaker 1>they detect a bacterial and a toxin, clots entrap the

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<v Speaker 1>invading bacteria, limiting further infection. Larger clots can also seal

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<v Speaker 1>a wound. Before L A L was discovered, BioMed companies

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<v Speaker 1>used rabbits to test for endotoxins because rabbit blood also

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<v Speaker 1>tends to clot in the presence of these toxins. If

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<v Speaker 1>after injection with the test substance and animal developed signs

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<v Speaker 1>of infection, which could take up to forty eight hours,

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<v Speaker 1>the sample was determined to be contaminated and the rabbit

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<v Speaker 1>would die. The discovery of L A L has saved

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<v Speaker 1>countless rabbits from this fatal testing, but in turn, hundreds

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<v Speaker 1>of thousands of crabs every year participate in an involuntary

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<v Speaker 1>blood drive to harvest horseshoe crab blood. The unspecting creatures,

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<v Speaker 1>larger females being preferred, are hauled out of shallow coastal

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<v Speaker 1>areas and brought to a lab where they're chilled for

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<v Speaker 1>an hour or so, and then of the crabs blood

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<v Speaker 1>is drained off. After leading, the animals are returned to

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<v Speaker 1>the ocean. The sooner they're returned, the more likely they

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<v Speaker 1>are to survive, which is important because though this is

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<v Speaker 1>considered a low mortality catch and release procedure, as many

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<v Speaker 1>as thirty percent of horseshoe crabs can die from the

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<v Speaker 1>bleeding process, and because of the demand for L A

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<v Speaker 1>L the toll on horseshoe crabs can be huge. Six

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<v Speaker 1>hundred thousand crabs are harvested every year for BioMed purposes,

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<v Speaker 1>meaning up to a hundred and eighty thousand crabs may

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<v Speaker 1>be lost to the procedure every year, and the long

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<v Speaker 1>term impact may be much worse. In areas where the

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<v Speaker 1>most crabs are harvested for blood letting, fewer females show

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<v Speaker 1>up to spawn. North America's own Limuleus polyphemus was placed

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<v Speaker 1>on the vulnerable list by the International Union for the

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<v Speaker 1>Conservation of Nature in and the problem is worse in Asia,

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<v Speaker 1>where no animals are returned to their habitat. Tan O

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<v Speaker 1>Creti said in Singapore, during the breeding season, ten thousand

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<v Speaker 1>adults per day are harvested blood out and then prepared

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<v Speaker 1>for sale as food. At this rate, they could be extinct.

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<v Speaker 1>At this rate, they could be extinct there in a decade.

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<v Speaker 1>Tennecredi boils down the next steps needed quote. Three things

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<v Speaker 1>have to happen immediately and consistently, one stop all collection

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<v Speaker 1>for bait to get FDA approval of synthetic L A L,

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<v Speaker 1>and three protect crab breeding sites. There has been progress

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<v Speaker 1>on synthetic L A L. Although an effective L A

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<v Speaker 1>L substitute has been available for fifteen years, only one

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<v Speaker 1>facility could produce it, and BioMed companies didn't want to

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<v Speaker 1>rely on a single source. But then another facility began

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<v Speaker 1>production and Eli Lillian Company announced it would phase out

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<v Speaker 1>natural L A L by in the next few years

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<v Speaker 1>and phase in synthetic L A L. Good news. Indeed.

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<v Speaker 1>Today's episode was written by Laura and Fick and produced

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<v Speaker 1>by Tyler Clang for iHeart Radio's How Stuff Works. For

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<v Speaker 1>more on this and lots of other continually spawning topics,

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<v Speaker 1>visit our home planet how stuff Works dot com and

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<v Speaker 1>for more podcasts. For my heart Radio, visit the iHeart

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<v Speaker 1>Radio app, Apple Podcasts, or where where you listen to

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