I've had some experience with crayfish (crawdads) on two different occasions. My first experience was a wild caught one from Arkansas that I took home (California) and stuck in my tank and he lived a long time until my brother stuck some plant crystals that suck water up and killed everything in the tank (I was about 9 and loved the fish tank, lets just say I made him VERY sorry for doing that).
The second time I was very unlucky/lucky (how ever you want to look at it) and got a crawdad from my neighbor in germany who got them from the fish store. He was missing one claw so I took it. Well, after a couple of months I had about 4 baby crayfish. A couple months later I had 1 great crayfish, 4 parent crayfish and about 10 baby crayfish. After doing some research I came to find out I had a self procreating species. It was a pretty thing until I got tired of them making babies without permission. They are called Marmorkrebs or marbled crawdads.
The second time I was very unlucky/lucky (how ever you want to look at it) and got a crawdad from my neighbor in germany who got them from the fish store. He was missing one claw so I took it. Well, after a couple of months I had about 4 baby crayfish. A couple months later I had 1 great crayfish, 4 parent crayfish and about 10 baby crayfish. After doing some research I came to find out I had a self procreating species. It was a pretty thing until I got tired of them making babies without permission. They are called Marmorkrebs or marbled crawdads.