A small crustacean is a type of aquatic arthropod that can range in size from microscopic to over a foot long. Woodlouse (9 letters) is a small, terrestrial crustacean that lives in damp environments. SHRIMP (6 letters) are small, swimming crustaceans that are commonly used as food. Isopod (6 letters) is a type of crustacean that is usually found in the ocean and has a segmented body. Waterflea (9 letters) is a small, freshwater crustacean that is often used as a food source for fish.