"Here's a number that will blow your mind: the horseshoe crab has been on Earth for about 450 million years. That's 200 million years older than the dinosaurs. They've survived five mass extinctions. They watched the dinosaurs come and go. They were here before the first fish, before the first tree. And right here on Florida's shores, they're still coming up out of the water to mate — just like they always have."
Older Than the Dinosaurs
The horseshoe crab (Limulus polyphemus) is one of the oldest living animals on Earth. Horseshoe crabs have existed for roughly 450 million years — predating the dinosaurs by about 200 million years. They have survived all five mass extinction events in Earth's history, including the one that wiped out the dinosaurs 66 million years ago. Despite their name, they are not crabs at all — they are more closely related to spiders and scorpions. The species we see on Florida's shores today is essentially unchanged from its ancestors that crawled through the shallow seas of the Paleozoic era. For scale: when the first horseshoe crabs appeared, there were no trees on land, no fish in the sea, and Florida did not exist. The fact that this ancient animal is still here — on the same beaches where people now build condos — is one of the great wonders of nature. And it turns out, modern medicine cannot function without them.