Photo of the Day #485: Horseshoe crab and ladybugs

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The shell of a horseshoe crab (Limulus polyphemus) crawling withe ladybugs (Coccinellidae). Photographed at Cape Henlopen State Park, Delaware.

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A horseshoe crab (Limulus polyphemus), photographed at Cape Henlopen State Park, Delaware.This weekend I'm headed off to see the annual breeding explosion of horseshoe crabs (Limulus polyphemus) in Delaware Bay. During late May and early June, especially during the full and new moon, scores of the…
Gastropods eating the shell and gills of a horseshoe crab (Limulus polyphemus). Photographed May 17, 2008 at Cape Henlopen State Park, Delaware.
A horseshoe crab (Limulus polyphemus) sculling about in the shallows at Cape Henlopen State Park, Delaware.
A horseshoe crab (Limulus polyphemus), photographed at Cape Henlopen State Park, Delaware.

hurm. Looks penguinish to me. You upload the right picture?

Great photo! Were the ladybirds hunting insect scavengers on the carapace or were they directly scavenging on the horseshoe crab themselves? This picture is a really great portrait of arthropod evolution and the dramatic difference between the terrestrial and marine arthropod faunas...brilliant...

Neil; If you want, I can send you the original hi-res version.

Your question brings up a conundrum about ladybugs that I have yet to find an answer to. During the middle of the spring (April through May, this photo was taken just after finals) I have often seen hordes of ladybugs on the beach. In this case they were on the Limulus carapace, but other times they have just been on the sand. They are often clumped together and not dispersed evenly over the beach. I asked an entomologist at one point and he said he could only imagine that they had been blown onto the beach for some reason, but the regularity with which I see ladybugs on the beach in the spring leads me to think there's something else going on.