Some sea slugs do not immediately digest the chloroplasts that are found in the algae that they graze upon. Most researchers have argued these captured chloroplasts (often called kleptoplasts because they are stolen) are very slowly digested as snacks. Now a team has explored this odd phenomenon and found that the stolen chloroplasts are functioning like batteries to help enhance the overall fitness of the sea slugs that have captured them.
Ready to reproduce!
Image Courtesy of Sonia Cruz.
To study this, the team radioactively labelled compounds produced by the chloroplasts and tracked them around the bodies of the sea slugs. Amazingly, they found the compounds migrating into slug sexual organs and are playing a part there in the production of compounds that are used in reproduction. Stunned, they wondered what would happen if they interfered with the photosynthetic activity of the these chloroplasts. Sure enough, when the team did this, the slugs that had these stolen chloroplasts reproduced less.
All told, while these slugs are not actually photosynthetic organisms, they get a big sexual boost by stealing chloroplasts from algae and harnessing the nutrients that they generate from sunlight. You can read more in The Economist article that I wrote on this here.