My emeral crabs are doing it?

[zrograviti]

I just saw my bigger crab attacking the smaller one. so I was about to stick my hand in and stop him. I took a closer look, the small one was a female and her bottom cover thingy(?) was opened. is my crab going to be a mother now? I don't know what it's called, the thing that I called the bottom cover(lol), the one that has wider thingy is female, right?

[Mr.Lloyd]

Yes,breeding will happen in your tank.I have sand sifting starfish that spend more time on top of each other than they do sifting the sand looking for food.I have found plenty of new little this and thats over the years.Enjoy!