The giant freshwater crayfish (Astacopsis gouldi) is the largest freshwater invertebrate in the world. These native Tasmanian crayfish are bigger than any found in the Amazon, the Congo or the Mississippi! The giant freshwater crayfish is also often called the giant freshwater lobster, but lobster usually refers to marine species. Here are some pictures of giant freshwater crayfish. A big thankyou goes to the world renowned expert on their ecology, Todd Walsh, who provided these pictures.