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Fun Facts About Horseshoe Crabs

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They’re funny little things.  First time I saw a horseshoe crab was kayaking at Hagen’s Cove, Florida near Steinhatchee.  As I was kayaking toward the islands, something scooted under me on the bottom of the ocean.  At first I thought it was a stingray. Then when I got a look at it, I really had no idea what it was? What exactly are horseshoe crabs? Manta Rays with armor?

My friend, who grew up on the Gulf Coast, told me it was a horseshoe crab.  Taking a look at the tail, I asked her does it sting or bite? “No.” she told me. Okay then what exactly does it do?  They look like something from when dinosaurs roamed the earth.

Fun Facts About Horseshoe Crabs

So I decided to do some research about these funny looking guys and learned so much! First they’re considered living fossils and they do actually predate dinosaurs on the earth.  Some scientists estimate one of the species to have been around 450 million years! What a gene pool right? 

Even though they’re called crabs, they’re not actually crabs.  They’re actually more like a spider. Like arachnids, they have legs positioned near their mouths. These legs are actually like pinchers that help move food closer to their mouths and crush it up. What do horseshoe crabs eat?  They foods of choice are sea worms, mollusks and crustaceans. (Sea worms?)

Like me many folks think the tail might be dangerous but it’s not. It’s mainly used for steering and to flip themselves if they land on their backs.  Even cooler? These guys can swim upside down.

Talk about making babies!

And talk about making babies!  Each spring, these busy little guys make their way upshore to mate and lay their eggs at night.  Delaware Bay is one of the most popular love drive-ins where you can see hundreds mating and laying their eggs.  4,000 clusters of eggs will be deposited by the females and she will repeat this several times each night. Sometimes laying up to 20,000 eggs in an evening. Wow! What a job!

That may sound like a lot of eggs if you add it up, but most of these eggs won’t make it horseshoe crab status.  They’ll be eaten by migratory birds, some fish and sea turtles. Part of the food chain.

Talk about seeing clearly, horseshoe crabs have 9 eyes. Why so many eyes? Some are used to look for a mate while others are used to detect movement and see at night.

It takes 10 years for horseshoe crabs to reach maturity.  Along the way, they’ll shed their exoskeleton (outside) an average of 16 times before they reach mature adults. After that, it’s unsual for them to shed their exoskeleton.

And finally, they’re medical heroes to us humans.  They don’t have blood like we do. Rather they have amebocytes that attack viruses and other pathogens by trapping them in  a wall of gooky stuff.   Scientists use this amebocytes to test the safety of bloods and vaccines.  It’s not a pretty sight though.

Roughly 30% of the horseshoe crab’s blood is extracted then they are released back into the water. Unfortunately quite a few don’t recover from the process and die. That’s a pretty large number for an animal that’s helping us humans.  Scientists are looking for a synthetic option and I hope they find one quickly. National Geographic has an article about how the horseshoe crab is helping to develop a vaccine for Covid-19. You can read it here: Horseshoe crab blood is key to making a COVID-19 vaccine—but the ecosystem may suffer.

And there you have it.  Aren’t horseshoe crabs fascinating? I have to say now that I know more about them, they’re probably one of my favorite to see when I kayak on the west coast.

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About Denise

Denise Sanger lives a life split between her love for fitness and her passion for travel particularly to the BEACH.  Denise also has a love of marketing and lives in beautiful Suwannee County, Florida. You can find out more about Denise here: About Denise

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