The birds, the bees, and the snails in my lab

Mating Crepidula fornicata. Photo credit A. Cahill

It's summer. I can tell because I'm working crazy hours again and loving almost every minute of it.

Last Saturday night, around midnight, I was feeding the snails in the lab when I found a mating stack, something I've never seen before. The female had become detached from her substrate, which is why I could see what was going on. She's the bottommost snail on the stack below, with her head towards the right of the shell. Normally she would be holding on to the side of the tank with her large, muscular foot.

You can see two males trying to inseminate her in this photo. The one on the right is the male closest to her in the stack, and he was actively mating at the time. I could tell because the male on the left (second from the female in the stack) withdrew into his shell when I disturbed the water, but the other guy carried on as if nothing was the matter.

The next morning I came back in and the closer male had finished and withdrawn, but the other male was now actively mating with the female. Then I flipped the stack over so the female would be able to reattach to the tank and survive, so I don't know how the drama ended.

Female C. fornicata can store sperm from multiple matings for many months (probably over a year). The eggs that are ultimately laid by this female will have been fertilized by several males -- maybe even all of the males in her stack. And then I will have more larvae to study, and the circle of life work continues on.