I am given to understand that "crawdad" and "crayfish" refer to the same creature (or group of creatures resembling small lobsters that live in freshwater), and that the difference is dialectical.

According to Wikipedia, "crayfish" becomes "crawfish" in parts of the US ([1]), but what brought on the "-dad" ending change?


  [1]: https://en.wikipedia.org/wiki/Crayfish "Wikipedia - Crayfish"