The project focuses on the functionality between photosynthetical chloroplasts found in the opisthobranch genera Elysia and Hermea (Saccoglossans). "State of the art" bio optical methods (Pulse Amplitude Modylated fluorometry, spectral absorbtion/Fluoresc ens/irradiance and HPLC) will be used to: identify/quantify photosynthetical processes, to characterize seaslugs using chloroplasts as as food from those retaining chloroplasts and utilizing them as solar powered cells, and to investigate ecological adapt ions or possible evolutionary processes (adaptations). The objecties are: -to describe the anatomy and incorporation of chloroplasts inside the digestive gland in the marine snails by histological methods (detect and visualize the chloroplast sites). -to detect the photosynthetic performance in vivo and in situ by using Pulse Amplitude Modulated fluorometry (PAM), spectral in vivo absorbtion, fluorescens and irradiance (light harvesting and utilization). -to isolate chloroplasts taken from seaslugs (time-series) and characterize pigment composition/functionality (light- and photoprotective pigments versus degraded pigments). -to explain how an incorporated chloroplast obtain its functionality inside the digestive gland of a saccoglossan: to see if saccoglossans adapt to the environment, or if it is a highly coevolved process.