Atlantic horseshoe crab - Limulus polyphemus

Male

That's a male. You can tell by the second pair of limbs, which in males are shaped like boxing gloves. These are used to hang onto the female during breeding, and you can tell recently bred females sometimes by the presence of wear spots where a male had been clinging to her tail and carapace.

… Jonas Insinga, 4 March, 2012 - 11:42am

Thanks

… John R. Maxwell, 4 March, 2012 - 11:48am

Any time!

I have several shots of these animals from Durham, NH, where they clamber up into the brackish lower waters of the Oyster River, that I could upload to BugGuide. They include close-ups of the male legs and the gnathobase (the chewing, spiny plates surrounding the mouth.)

… Jonas Insinga, 4 March, 2012 - 7:11pm

Here is something

Maybe a female? I liked the hind leg/claw that appears to have 3 pincers on one limb.

Not many people at BugGuide are interested in "crabs" of any type. I recently posted some images of pet Coenobita clypeatus (Caribbean hermit crab) to possibly be used as placeholder images (until we got wild replacements). They would have added a new family (Coenobitidae) to the guide, but no one was interested. People here trip over themselves trying to see how fast they can add guide pages for Butterfly House images as placeholder for some lep that has been recorded in the US once after some hurricane 50 years ago! Yet they totally ignore a crab that actually lives in southern Fl. :-)

… John R. Maxwell, 5 March, 2012 - 12:59am

Probably.

Yeah, you're probably right about it being female.

I have only a rather basic knowledge of crabs. I wish I knew more. To be honest I was surprised that they were added to the guide because I seem to recall some apprehension to the idea of marine crustaceans being added.

… Jonas Insinga, 5 March, 2012 - 6:50pm