Crabs and The Missionary Position

I finished reading a really good book called Beautiful Swimmers (I have mentioned it in a previous post) while sitting pool side in Las Vegas last weekend. And before it all disappears into the recesses of my mind I thought I'd write about it.
I don't know why but for some reason I find crustacean mating rituals really interesting. I am not sure if it's because I never really thought about it before (so it's all new to me), or if through my own anthropomorphic tendencies I think it's really romantic. But anyway I think it's really cool, and I know I say this a lot but totally amazing!

Blue crab females only mate once in their lives, and they can only do it when they have just molted. Timing is everything because within 12 hours of the molt the shell of the female is already hardened too much to allow copulation to occur. Somehow the males know when the the females are going to begin their molt, and woo them before they begin to shed. The normal rigmarole ensues with the female accepting or declining her suitor. Once she has chosen she assumes a friendly posture and the male stands up on his tippy-toes and pulls the female under him and holds her with his walking legs creating a little "cage" around her. This is called the precopulatory embrace (isn't that just the sweetest sounding thing?). The male does this not to keep the female in, but to protect her from other crabs and fish while she sheds her old shell. He stands guard while she, sheltered from predators, wiggles out of her old shell. Once she's done, the male flips her over so they are stomach to stomach, she exposes her gonophores (openings that receive sperm) and he uses his gonopods to deliver the it. This can take anywhere from 5 to 12 hours.
Then the male flips the female back around and faces her forward and he continues to cradle and protect her until her shell is fully hardened and she is no longer vulnerable. This takes about two or so days. After that they go their separate ways, and the next spring their babies are born. It may not last forever, but isn't that about the most romantic thing you've ever heard? Chivalry may be dead in humans, but I am happy to report it's alive and well in the sex lives of blue crabs.


P.S. When I wrote the title it took me a minute to realize the subject of this blog could be seriously misinterpreted from just glancing at the name. But I decided to leave it because I think it's funny even though it was by accident.