Mollusks have bilateral symmetry and are coelomed protostomes, but the coelom is only represented by small residual spaces around the pericardial cavity, the gonads, some parts of the nephridia, and in some cases part of the intestine. The foot is used primarily as a means of movement. The foot is also a very important structure, although it has adapted differently depending on the classes of mollusks. It is characterized by having a really powerful and complex musculature. The most widespread use of this organ is that of locomotion, as happens with gastropods. However, in bivalves it serves to burrow or in cephalopods it helps to provide propulsion.
