I found it surprising that some shellfish are found in freshwater.
I have heard of freshwater pearls, so I'm not so surprised.  How many kinds are there?
I am not sure as to the number but I do know that some crustaceans that are enjoyed by diners are lobster, shrimp, and crabs.
Are crawfish from fresh water?
Crayfish
Crayfish, also known as crawfish, crawdads, freshwater lobsters, mountain lobsters, mudbugs, or yabbies are freshwater crustaceans resembling small lobsters (to which they are related). Taxonomically, they are members of the superfamilies Astacoidea and Parastacoidea. They breathe through feather-like gills. Some species are found in brooks and streams where fresh water is running, while others thrive in swamps, ditches, and paddy fields. Most crayfish cannot tolerate polluted water, although some species such as "Procambarus clarkii" are hardier
"I have been labeled as an Intelligent Design (ID) proponent. I am not. I do not know how to use science to prove intelligent design although some others might. I am sympathetic to the arguments on the matter and I find some of them intriguing, but the scientific proof is not there, in my opinion. So I prefer to be free of that ID label."
He had also said that he felt the explanations offered by evolution are incomplete, and he found it hard to believe that