Solar-powered slug steals chloroplasts and stores them for emergencies

‘Solar-powered’ sea slugs (Elysia crispata) steal photosynthetic equipment from algae and stockpile it to use as an energy source on a rainy day. The slugs store these stolen tools, called chloroplasts, in specialised depots in their cells — dubbed ‘kleptosomes’. Day-to-day, the chloroplasts let the slugs make nutrients using energy from sunlight. But when the going gets tough the energy-makers become food: the slug breaks them down and absorbs the resulting nutrients. Using this trick, researchers found that Elysia can survive for up to four months without another food source.