| A | B |
|---|
| Phylum Molluska | all have soft bodies; some have calcium carbonate shells |
| Phylum Annelida | all are segmented |
| Phylum Arthropoda | all have jointed appendages |
| Phylum Echinodermata | all have spiny skin |
| Class Gastropoda | class of mollusks with one shell or no shell (snails, slugs) |
| Class Bivalvai | class of mollusks with two shells (clams, oysters) |
| Class Cephalopoda | class of mollusks that have their head and feet in the same area (octopus, squid, chambered nautilus) |
| Class Oligocheata | class of annelids with few bristles (earthworm) |
| Class Polycheata | class of annelids with many bristles (Nereis) |
| Class Hirudinea | class of annelids without bristles (leeches) |
| Subphylum Trilobita | extinct arthropod (trilobite) |
| Subphylum Chelicerata | arthropod with chelicera mouth parts (spiders, mites, ticks, hourseshoe crabs) |
| Subphylum Crustacea | arthropods with birameous appendages (crayfish, lobster) |
| Class Arachinida | Class to which spiders belong |
| Class Insecta | Class to which insects belong |
