What are Horseshoe Crab Blood Uses?

horseshoe crabs, horseshoe crab blood uses
Horseshoe Crabs mating on the beach (via Wikimedia Commons)

What are Horseshoe Crab Blood Uses and How Do They Spawn

Spawning time!


Hi, I’m Edna, a horseshoe crab. I’m not truly a crab, but an arthropod related to scorpions, spiders and ticks. I’m excited because it is the new moon. It is time for me to mate and lay my eggs in the sand. This is a big deal to us horseshoe crabs to actually come out of the water for this special event.

It’s getting dark and the tide is high-I sense it’s time to crawl out of the water. I don’t have good vision, even though I have up to 10 eyes! Although I don’t see as well as humans, my vision is one million times better at night than in the day.

My special chemicals, or pheromones, that I release into the water attract male horseshoe crabs to me in the surf. One of them latches onto my back with a special claw. It’s almost time to lay my eggs!

I begin my climb out of the surf. Waves crash all around me until I make it to the wet sand. I climb out a little further and begin digging a hole to lay my 4,000 eggs. I dig and dig, and finally begin to deposit my eggs. The male horseshoe crab clasped to me fertilizes the eggs as they come out of me.
I finish laying my eggs in the sand, and the male detaches from me.

Where am I going?

Wait, why am I floating in the air? What happened to the sand and water? Something has grasped me. Am I doomed?


I am in a dark place. I scramble to crawl up the wall placed before me but it’s no use. My legs just keep scratching up against something, but I can’t crawl out or over it.

Lots of other horseshoe crabs are piled around me. I sense the moonlight one moment, and the next it is gone. I thought my life might end being eaten by a shark, but surrounded by my fellow horseshoe crabs in the dark?

Where am I?


I am tired after laying all those eggs, so I sleep. When I wake up I am in a bright area. It’s not the warm sun, but there is light all around. I can move all my legs, but I can’t go anywhere. I feel my blue blood being drained from me by a cord, and it’s not a good feeling.

Back home!

Soon enough I am lifted in the air and placed in the dark place again with all the other horseshoe crabs. After what feels like hours, I feel myself lifted into the air again. The warm sun is all around me. Then I am placed down on the wet sand. I’m home! I scurry into the surf and back into the water. What a night and day I’ve had!

Note: So what are horseshoe crab blood uses? Horseshoe crabs blue blood is harvested by the biomedical industry for testing of drugs and medical devices. Their blood is blue because they use copper as a carrier for oxygen, while humans use iron as a carrier of oxygen in their red blood. There are synthetic alternatives to LAL, but their use isn’t fully adopted yet.

It is unknown if all the biomedical industries actually return all the horseshoe crabs they bleed back into the wild as they may be sold for bait instead. There has been a study that horseshoe crabs that are bled and returned to the wild have altered behavior and the females less spawning attempts.

The Atlantic Horseshoe Crab is “Near Threatened” to being endangered.

Check out these websites for more information:
Biomedical bleeding may impact horseshoe crabs spawning behavior and movement

More on horseshoe crab spawning and how to donate to help them!

And check out Plankton:The Real Monsters of the Ocean