I don’t know how clearly you can see these- but these are hundreds of Fiddler Crabs who live in the marsh mud in our tidal creeks. They are a little army that comes out of the mud in the summer when it’s 80 degrees or hotter. They wave their big claw and look very fierce ( and actually are if they pinch you!) They live in these little mud holes and come out when the tide is down. Fiddler on the Creek has them everywhere and they are such fun to watch!
We used to go to Hatteras in the summer and there were always lots of fiddler crabs. Not nearly as many as in your photos though. I don't think we have them in California. Maybe they are an East Coast crab?
…i love fiddler crabs. they seem so cranky in a way, but cute at the same time! they also seem to have boundless energy…i have to admit, i have never seen so many though…pretty impressive. mickey