CRUSTACEANS

"Crustaceans form a major and very diverse group within the arthropod phylum. Most live in the marine waters around the globe today, and are the familiar giant spider crab in front of you, lobsters, shrimp, even barnacles which are also crustaceans. The tiny sow bugs which you have probably seen in your garden plot, are the only crustaceans that live on land. They are the only ones that are able to breathe air. All the rest of the crustaceans must take their oxygen from sea water or from fresh water."