WEBVTT
Kind: captions
Language: en

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Ancestors of horseshoe crabs date back over
450 million years!

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So the horseshoe crab is oftentimes called
the dinosaur of the ocean.

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Because it’s been around since before the
dinosaurs.

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The dinosaurs went extinct - this guy stayed
around.

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Horseshoe crabs are arthropods - that means
they have an exoskeleton, a segmented body,

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and jointed appendages, but they don’t have
a backbone.

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Horseshoe crabs molt, leaving their old shells
behind and growing new, larger shells.

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Their main eyes are compound, like a housefly’s,
but they also have five more eyes on top of

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their shells, and two underneath!

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They have sensory eyes here, all along their
shell and down their tail, and they can tell

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moonlight, sunlight.

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They have sensors as well, and they can tell
the temperature of the water, the dissolved

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oxygen, all of that just from their body.

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The coolest thing about horseshoe crabs, though,
is their blood.

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It’s actually blue, and copper-based!

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And it’s really useful.

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When this crab gets injured, gets a little
cut on its body, bacteria can get into it

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from the water.

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So the Horseshoe crab blood actually Jell-O’s
around that bacteria and stops it from getting

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into the Horseshoe crab body.

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Because of its special properties, scientists
can use horseshoe crab blood to sniff out

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any harmful bacteria that might be present
in medicines for humans.

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There’s this compound called Limulus Amoebocyte
Lysate, otherwise known as LAL.

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They use the LAL to test every vaccine, needle,
medical equipment, anything that goes into

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your body is tested with the LAL.

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While scientists are working on synthetic
alternatives to horseshoe crab blood, every

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time you get a shot, you have a horseshoe
crab to thank!