Malacology is the branch of
invertebrate zoology that deals with the study of the
Mollusca (mollusks or molluscs), the second-largest
phylum of animals in terms of described
species after the
arthropods. Mollusks include
snails and
slugs,
clams,
octopus and
squid, and numerous other kinds, many (but by no means all) of which have
shells. One division of malacology,
conchology, is devoted to the study of mollusk shells. Malacology derives from
Greek ,
malakos, "soft"; and ,
-logia.