Living in glass houses

...you don't get no privacy.

It was 10 PM, so I went to turn off the aquarium lights. As usual, I looked in to see how things were going; everybody happy? No disasters, no panics? All was calm.

But in the back, half-hidden beside the pump, a pair of crabs were getting ready to mate. I went for the camera.

A tangle of legs. Ma Crab's back. He's underneath her.

It's hard to mate when you're encased in a rigid shell. Crabs have to wait until the female molts; when her new outfit is still soft and pliable, there's a brief window of opportunity, not to be wasted. Her consort, finding her in the process of opening up, grabs her, belly to belly, and holds on until she backs out of the old shell. This may take several hours, or even days. He may even help her with the process; mainly, though, he's making sure he's at hand when the moment comes, and that no other male gets her. (Not a problem for him in the aquarium; there's only one other male, still too young, but he's not taking risks.)

Since his last molt, Pa Crab has been ready, swaggering about with full-size pincers, often frightening the smaller female. Not today; this morning she was hanging around near him. Now, she has allowed him to embrace her tightly. In the photo above, you can see his legs, the striped ones, (hers are spotted) hugging her. Both of them hold their pincers up and away from the body, claws open. They move about, slowly, getting comfortable. After a bit, they squirm down underneath the pump, where they are more private.

I don't know how long it will be until they mate.

Sculpted curves and "teeth" of the female's carapace. Two of her pincers, one of his.