Their Ancestors Survived the Last Great Extinction. Will Horseshoe crabs Survive Us?

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It’s that time of the year again on Long Island, Atlantic horseshoe crabs (Limulus Polyphemus) travel from the depths of the ocean to cruise our beaches in search of romantic rendezvous. Female horseshoe crabs carry thousands of eggs to deposit in the sand at the upper edges of the high tide line. Males follow, jostling each other for position behind a female. The successful male will fertilize the eggs after the female deposits her eggs in a shallow nest. They will remain together depositing and fertilizing eggs while the tide recedes. On the next high tide the female will pull the male back out to deeper water. She may repeat these rendezvous 4 or 5 times during the spawning season with potentially new males competing each time.

Mud snails (Ilyanassa obsoleta) in a sand depression.

Back when I worked as a naturalist on the Long Island Aquarium tour boat I learned that mud snails (Ilyanassa obsoleta) are attracted to freshly laid horseshoe crab eggs, clumping by the dozens in the depressions left behind by the crabs, so it’s an easy way to find a nest. I was recently delighted to unexpectedly come across such a site, especially because it was on a rocky beach popularly used by dog walkers, along the shores of the very busy Port Jefferson Harbor.

Horseshoe crab eggs.

But my delight was crushed yesterday when I found the dead body of a very large female whose carapace showed signs of being stabbed. Was this an intentional act of cruelty or ignorance. I will not know. Are there still people who fear horseshoe crabs, thinking the tail (telson) is used as a weapon?

Large body of a dead female horseshoe crab.
Horseshoe crab females develop approximately 80,000 eggs every year and will lay around 20 cluster of eggs each spawning season.

We just have to continue educating people on how important these animals are to us and our environment. Their ancestors have been around for over 450 million years and survived the extinction of the dinosaurs. Let’s save these magical encounters with “living fossils” for future generations to experience.

Some Links for more information:

Wikipedia – Horseshoe crab

ERDG The Horseshoe Crab

IFLScience – How Horseshoe Crab Blood Saves Millions of Lives

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