Elysia crispata is a herbivorous suctorial feeder. This species will eat the cell sap of algae but do not digest all of it. The lettuce sea slug will use its radula to pierce algal cells and suck their contents out by using its pharynx. Some of the chloroplasts that Elysia crispata eat are not digested. Instead, they are funneled through specific passages in the digestive tract and stored in the parapodia. These chloroplasts, which can live inside the E. crispata for up to four months, undergo photosynthesis while living in the parapodia.
The importance of Sacoglossan kleptoplasty (the use of chloroplasts) has been analyzed in close relatives of Elysia crispata. In an experiment on Elysia timida, specimens kept in the dark for 28 days were found to have lower survival rates (up to -30%) than those kept in the light. This leads us to believe that kleptoplasts provide these mollusks with extra energy to compensate for a shortage of food.
Plant Foods: algae
Primary Diet: herbivore (Algivore)