Every year, thousands of Atlantic Horseshoe Crabs Limulus polyphemus take advantage of the Spring high tides to haul themselves up onto the beaches of the Delaware Bay to spawn. These crabs were photographed at high tide this last weekend, by the light of the full moon, as they swarmed onto a Delaware beach (click through for larger versions). These prehistoric-looking creatures look like trilobites emerging from the primordial soup!:
Here’s what these crabs look like during daylight hours:
Some beaches are briefly covered by thousands of crabs:
The abundance of crab eggs in the sand attracts flocks of migrant shorebirds, like these Semipalmated Sandpipers Calidris pusilla, which pause to refuel on their journey north to their breeding grounds:
Other birds, such as gulls, also take advantage of the abundant food supply. Here, this Ring-billed Gull Larus delawarensis is devouring a clump of eggs it found amongst the spawning crabs:
The crabs, and the other wildlife they attract, make for quite a spectacle!
Click through for larger versions of all these images.
Thanks for the magical moonlit photos and a fascinating post. Have always loved horseshoe crabs, though I've never witnessed a sight like the one you describe.
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