Often thought of as the most intelligent invertebrates. They have a very advanced brain and nervous system, keen vision and tentacles with great tactile ability. Metabolic rates are high and these mollusks have a closed circulatory system. They can swim using fins or are jet propelled. They have beak like teeth for feeding.
Muscular foot produces slime to aid in locomotion.
The circulatory system is open with a two chambered heart pushing blood around the coelom. The respiratory structures have blood vessels associated with them. The blood is blue because copper is the basis of the hemocyanin pigment. The life cycle of all gastropods include a trochophore larva stage. Some times this is free swimming, may remain in the eggs.