| A | B |
|---|
| Pelecypoda | hatchet foot |
| Gastropoda | stomach foot |
| Amphineura | double nerve |
| Polyplacophora | many plates |
| Cephalopoda | head foot |
| Monoplacophora | single plate |
| Scaphopoda | boat foot |
| radula | rasping tongue |
| mantle | secretes nacre |
| nacre | mother-of-pearl |
| periostracum | horny protein layer |
| prismatic | crystalline shell layer |
| nacreous | smooth shell layer |
| pearl | object covered with nacre |
| foot | used for locomotion |
| byssal threads | used for attachment |
| Bivalvia | two valves, or shells |
| nudibranch | naked gill |
| cones | venomous to humans |
| giant squid | largest invertebrate |
| giant clam | most massive invertebrate |
| octopus | most intelligent invertebrate |
| chromatophores | used for color changes |
| cuttle bone | used for caged birds |
| tentacles | modified foot |
| ammonites | extinct cephalopods |
| fouling | result of torsion |
| pneumostoma | breathing hole in slugs |
| nautilus | only shelled cephalopod |
| cowrie | nacreous layer is external |
| zebra mussel | invasive exotic species in No. Amer. |
| clams, oysters, mussels, etc. | bivalves (Bivalvia, Pelecypoda) |
| squid, octopi, cuttlefish, etc. | cephalopods (Cephalopoda) |
| snails, slugs, abalone, etc. | gastropods (Gastropoda) |
| tusks | scaphopods (Scaphopoda) |
| chitons | polyplacophorans (Polyplacophora, Amphineura) |
| veliger | mollusc larva |
| blue-ringed octopus | saliva contains neurotoxin |
| adductor muscles | hold valves open or closed |
| scallops | have several eyes |
