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?
Yes, crawfish are found in freshwater and they resemble small lobsters.
In the South I believe they are called crawdads.
Crawdads is a term that is used to refer to crayfish although I'm not sure if it's limited to the south.
I just saw an ad for Red Lobster where they have them on the menu!  Amazing!  They used to be low class seafood.
Crayfish as food
Crayfish are eaten all over the world. Like other edible crustaceans, only a small portion of the body of a crayfish is edible. In most prepared dishes, such as soups, bisques and étouffées, only the tail portion is served. At crawfish boils or other meals where the entire body of the crayfish is presented, other portions, such as the claw meat, may be eaten.
Claws of larger boiled specimens are often pulled apart to access the meat inside. Another favourite is to suck
"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