Now this is a very simple way to increase libido in women. According to a study, people experience an increase in their "dopamine" levels after looking at the photograph of their loved one for 30 seconds or more. Higher dopamine levels increase your desire to have sex. There are three main subclasses of gastropods; the Prosobranchia (ocean snails), Opisthobranchia (sea slugs, sea butterflies and sea hares), and Pulmonata (land and freshwater snails and slugs). Each of the subclasses has evolved in their own way and members differ in their reproduction and life cycles within the subclasses. The gastropod folks are so large it really is impossible to spell out living cycle of each one individual species, but a majority of general rules do apply. The more evolved the species, the more complex their reproductive cycle in addition to their biology. Here we will look at the life span cycle of a gastropod through various examples and how they differ with regards to the type.