Transform Boundaries The final type of boundary is one where the two plates slide against each other in a sideways motion. These boundaries between plates is referred to as transform boundaries.
The three regions of the body of the Mollusk are the head-foot, the visceral mass, and the mantle-shell.
Body Plan of the Mollusks In their basic body plan (figure 45.5), mollusks have dis-tinct bilateral symmetry. Their digestive, excretory, andreproductive organs are concentrated in a visceral mass, and a muscular foot is their primary mechanism of loco-motion.