Speaker 1: Welcome to brain Stuff from how Stuff Works. Hey, brain Stuff,
Speaker 1: Lauren Vogel Bomb. Here. When you look at a horseshoe crab,
Speaker 1: you're looking at half billion years into the past. These
Speaker 1: primitive animals were around long before the dinosaurs and survived
Speaker 1: ice ages and asteroids almost unchanged their cozy ecological Niche
Speaker 1: necessitated few body modifications, So while horseshoe crabs today are
Speaker 1: different than their ancestors, they're not that much different. You're
Speaker 1: also looking at a creature whose value approaches a half
Speaker 1: billion dollars a year to the biomedical and commercial fishing industries.
Speaker 1: The blood of horseshoe crabs is extremely important to science.
Speaker 1: It's capable of detecting a certain type of bacteria in humans,
Speaker 1: thereby saving lives. More on that in a moment, but
Speaker 1: a bit of biology first. Horseshoe crabs resemble semi circular
Speaker 1: armored tanks and are an appropriate army green to brown color.
Speaker 1: Despite their name, they are more closely related to spiders
Speaker 1: and scorpions than to crab abs. Of the four species
Speaker 1: of horseshoe crabs around today, Limulus polyphemus is found along
Speaker 1: North America's eastern coast from Maine to Mexico. The other
Speaker 1: three species are found in Southeast Asia. Horseshoe crabs can
Speaker 1: be found in abundance on many beaches near their spawning zones.
Speaker 1: They commonly become overturned by the action of waves during
Speaker 1: spawning and may not be able to write themselves, which
Speaker 1: leads to death. But not every horseshoe crab you see
Speaker 1: on the beach is dead. They also molt, leaving behind
Speaker 1: their old exo skeleton and forming a newer, bigger one.
Speaker 1: The horseshoe body has three sections. The large head or prosema,
Speaker 1: houses the brain and heart, and six pairs of appendages
Speaker 1: are attached to it. In males, the first pair are
Speaker 1: hook like and used to clamp onto a female during mating.
Speaker 1: In the abdomen or opus, those sma muscles control the
Speaker 1: gills and tail, called the tellson. The tellson serves as
Speaker 1: a rudder and helps crabs write themselves if they get
Speaker 1: flipped over during spawning. Females are third bigger than males
Speaker 1: and can weigh twice as much upwards of ten pounds
Speaker 1: that's about four and of kilos. It takes about ten
Speaker 1: years for horseshoe crab to grow to adult size. Spawning
Speaker 1: peaks in May and June. At high tide during the
Speaker 1: full or new moon, the female digs a hollow in
Speaker 1: the sand beneath her and lays a cluster of several
Speaker 1: thousand eggs, which are fertilized by the male clinging to
Speaker 1: her back. Satellite males closely follow the couple for the
Speaker 1: chance to pass on their jeans to some of the eggs.
Speaker 1: The female repeats the process several times per night and
Speaker 1: may spawn for several nights. All told, each breeding female
Speaker 1: can lay up to a hundred thousand eggs a season.
Speaker 1: Delaware Bay has the largest spotting population in the world
Speaker 1: and as a stop oversight for shorebirds in the Atlantic Flyway,
Speaker 1: which is the north south path to and from Arctic
Speaker 1: breeding grounds. Up to a million birds flocked to the
Speaker 1: site to gorge on horseshoe crab eggs, building their strength
Speaker 1: for the journey north. But decades of overharvesting crabs as
Speaker 1: bait to catch welk, eel and conk have decimated their
Speaker 1: populations and turned the egg feast into near famine. Hundreds
Speaker 1: of thousands of crabs are taken every year for bait.
Speaker 1: Then there's the effect of shoreline development and habitat loss. Beaches,
Speaker 1: intertidal flats, and deep bay waters are all necessary for
Speaker 1: crabs survival and reproduction, but are increasingly encroached upon by
Speaker 1: construction and poisoned by fertilizer runoff. We spoke via email
Speaker 1: with John Tannacretti, a professor of earthen environmental sciences at
Speaker 1: Malloy College and director of the Center for Environmental Research
Speaker 1: and Coastal Oceans Monitoring. He said we monitored more than
Speaker 1: a hundred and fifteen sites on Long Island for over
Speaker 1: seventeen years and found that horseshoe crab habitat has declined
Speaker 1: by more than eight percent. A loss of habitat means
Speaker 1: loss of breeding animals, clearly seen in the long term
Speaker 1: decline in horseshoe crabs in the area by about one
Speaker 1: percent per year. Though their health is critically threatened by humans,
Speaker 1: we benefit enormously from horseshoe crabs. Horseshoes. Copper based blue
Speaker 1: tinged blood contains a clotting agent called lumulus ambo site
Speaker 1: ly sate or l A L, which detects endotoxins released
Speaker 1: by bacteria that can cause fever, stroke, organ damage, and
Speaker 1: even death. L A L is used to test drugs, vaccines,
Speaker 1: and medical devices, and it's so essential to biomedical companies
Speaker 1: that manufacturing around the world would halt if the supply
Speaker 1: was cut off. Understandably, L A L is one of
Speaker 1: the most valuable fluids on Earth, at a price of
Speaker 1: about fifteen thousand dollars a quart. Horseshoe blood developed this
Speaker 1: remarkable clotting ability as a response to life in an
Speaker 1: oceanic soup of bacteria. When microbes invadim mammal, millions of
Speaker 1: tiny blood vessels limit their spread and white blood cells
Speaker 1: bite them off. But not so with horseshoe crabs. Their
Speaker 1: blood moves freely through their tissues and organs, providing a
Speaker 1: wide playing field for bacterial infection. But these bacteria and
Speaker 1: crabs have co evolved for millions of years, and so
Speaker 1: crabs have defenses to Horseshoe crabs don't have an immune
Speaker 1: system exactly. Their single type of blood cell and ambo site,
Speaker 1: which is a cell that can move around, does all
Speaker 1: the usual work of blood cells, repairing wounds, gobbling up
Speaker 1: dead cells, transporting and storing digested material. But these amibo
Speaker 1: sites also release a substance that clots like wild when
Speaker 1: they detect a bacterial and a toxin, clots entrap the
Speaker 1: invading bacteria, limiting further infection. Larger clots can also seal
Speaker 1: a wound. Before L A L was discovered, BioMed companies
Speaker 1: used rabbits to test for endotoxins because rabbit blood also
Speaker 1: tends to clot in the presence of these toxins. If
Speaker 1: after injection with the test substance and animal developed signs
Speaker 1: of infection, which could take up to forty eight hours,
Speaker 1: the sample was determined to be contaminated and the rabbit
Speaker 1: would die. The discovery of L A L has saved
Speaker 1: countless rabbits from this fatal testing, but in turn, hundreds
Speaker 1: of thousands of crabs every year participate in an involuntary
Speaker 1: blood drive to harvest horseshoe crab blood. The unspecting creatures,
Speaker 1: larger females being preferred, are hauled out of shallow coastal
Speaker 1: areas and brought to a lab where they're chilled for
Speaker 1: an hour or so, and then of the crabs blood
Speaker 1: is drained off. After leading, the animals are returned to
Speaker 1: the ocean. The sooner they're returned, the more likely they
Speaker 1: are to survive, which is important because though this is
Speaker 1: considered a low mortality catch and release procedure, as many
Speaker 1: as thirty percent of horseshoe crabs can die from the
Speaker 1: bleeding process, and because of the demand for L A
Speaker 1: L the toll on horseshoe crabs can be huge. Six
Speaker 1: hundred thousand crabs are harvested every year for BioMed purposes,
Speaker 1: meaning up to a hundred and eighty thousand crabs may
Speaker 1: be lost to the procedure every year, and the long
Speaker 1: term impact may be much worse. In areas where the
Speaker 1: most crabs are harvested for blood letting, fewer females show
Speaker 1: up to spawn. North America's own Limuleus polyphemus was placed
Speaker 1: on the vulnerable list by the International Union for the
Speaker 1: Conservation of Nature in and the problem is worse in Asia,
Speaker 1: where no animals are returned to their habitat. Tan O
Speaker 1: Creti said in Singapore, during the breeding season, ten thousand
Speaker 1: adults per day are harvested blood out and then prepared
Speaker 1: for sale as food. At this rate, they could be extinct.
Speaker 1: At this rate, they could be extinct there in a decade.
Speaker 1: Tennecredi boils down the next steps needed quote. Three things
Speaker 1: have to happen immediately and consistently, one stop all collection
Speaker 1: for bait to get FDA approval of synthetic L A L,
Speaker 1: and three protect crab breeding sites. There has been progress
Speaker 1: on synthetic L A L. Although an effective L A
Speaker 1: L substitute has been available for fifteen years, only one
Speaker 1: facility could produce it, and BioMed companies didn't want to
Speaker 1: rely on a single source. But then another facility began
Speaker 1: production and Eli Lillian Company announced it would phase out
Speaker 1: natural L A L by in the next few years
Speaker 1: and phase in synthetic L A L. Good news. Indeed.
Speaker 1: Today's episode was written by Laura and Fick and produced
Speaker 1: by Tyler Clang for iHeart Radio's How Stuff Works. For
Speaker 1: more on this and lots of other continually spawning topics,
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