Yabbies are a freshwater crustacean and outside of Australia are called freshwater crayfish. We have freshwater crayfish that are somewhat bigger than yabbies. Yabbies grow from 3" to 12" and have claws than can do some damage, especially those 6" and over. Bloody good eating.

I think what we call Crayfish and Lobster are the same thing and our Lobsters claws are not as large as American Lobsters, going by pics I have seen. Anybody know for sure.

May have to google this if nobody knows for sure.