2. Crab belongs to Lepidoptera and is a crustacean. Their bodies are protected by hard shells, and they breathe through their gills. Taxonomically, it is the same kind of animal as shrimp, lobster and hermit crab. Most kinds of crabs live in the ocean or offshore areas, and some live in fresh water or land. Common crabs are Portunus trituberculatus, Portunus trituberculatus, Eriocheir sinensis and Eriocheir sinensis (Eriocheir sinensis, Eriocheir sinensis and Eriocheir sinensis).