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ambience: Horseshoe crabs, birds, waves in background
Horseshoe crabs are one of the most ancient creatures on earth, older than man, even older than the dinosaurs. One of the keys to their success as a species is the way that they reproduce. I’m Jim Metzner, and this is the Pulse of the Planet. Mike Haramis is a research wildlife biologist with the US Geological Survey. He studies horseshoe crabs in Delaware Bay, where the river meets the sea.
“Wilmington Delaware is at the head of the estuary, and this estuary harbors the world’s largest population of horseshoe crabs. Horseshoe crabs are really not crabs; they’re more related to spiders – they look like the hoof of a horse. This area has uh, one to two million horseshoe crabs that spawn in the spring in a mass spawning event that is one of a, sort of natural wonder.”
7:02 “The crabs come ashore and spawn. They actually burrow into the sands of the beach head and deposit these casts of eggs which are actually cemented to small stones or course sand. The pattern seems to be that the crabs want to spawn as high on the beach as they can, so they choose the high spring tides, in which to peak their spawning. And then in the next month the eggs would be hatching, and the small looking horseshoe crabs would hatch and swim out into the into the bay.”
Horseshoe crabs always lay a surplus of eggs, which helps keep their population up , but what happens to all the eggs that don’t hatch? We’ll find out in our next program.
Pulse of the Planet is presented with support provided by the National Science Foundation. I’m Jim Metzner.