a snail has a basic anatomy like any other mollusk. they have a shell, a nervous system, a circulatory system, a respiratory system, and a reproductive system. the circulatory system has an open heart system, which pumps blood which flows over all of the organs in the snails body without veins or arteries. the respiratory system includes gills and lungs. they need gills to be able to live in water. they have lungs because their bodies adapted to their environment because of frequent droughts; so they need lungs to breathe during the droughts. their nervous system includes their brain, which controls their body. they are one of the only species of snails that are not hermaphrodites. each gender has its own reproductive parts.