are crustaceans bugs
Page 1 â Crustaceans â bugs of the sea. Crabs and crayfish are crustaceans, a subdivision of arthropods â the large group of animals without backbones (invertebrates) that includes insects, spiders, mites, scorpions and springtails.Arthropods have jointed legs and a hard outer shell that acts as a skeleton.rabs and crayfish are crustaceans, a subdivision of arthropods â the large group of animals without backbones (invertebrates) that includes insects, spiders, mites, scorpions and springtails.