Taken primarily from Kozloff, 1987, 1996 (Copyright 1987, 1996, University of Washington Press. Used in this web page by permission of University of Washington Press)
|Lower taxonomic level||Main Page||Alphabetic Index||Systematic Index||Glossary|
|1a||Flattened body has 8 dorsal shell plates, usually visible dorsally. Attach to rocks||Class Polyplacophora,
|1b||Body does not have 8 dorsal shell plates, may or may not be flattened||2|
|2a||Body laterally compressed, has two valves hinged together dorsally. Head rudimentary but often have large foot and gills||Class Bivalvia,
|2b||Body does not have two valves hinged together dorsally||3|
|3a||One shell, tubular, curved in less than 1/2 circle and opening on both ends, tapered so that one end is considerably smaller than the other||Class Scaphopoda,
|3b||Shell not as above||4|
|4a||Have 8 to 10 tentacles
with suckers instead of a creeping foot. No external shell (in our
area), but may have a reduced, internal shell. Mouth has a beak.
Large, complex eyes not on stalks
|4b||No shell, or have a single shell which is curved into a spiral, a pyramid,
or ear-shaped (in our area). Crawl on muscular creeping foot.
|5a||Gastropods with shells||Snails,
|5b||Gastropods without shells||Nudibranchs