Elysia chlorotica not only resembles a leaf, but uses plant-type cells to draw energy from the sun, too! This remarkable seaslug is able to extract chloroplasts from the algae it feeds on and incorporate them into their own tissues. The young slugs feed on algae and digest everything but the photosynthesising organelles, which are stored in the intestine and then actually taken up by the host cells themselves. The chloroplasts remain fully functional for up to a year, and nourish the slug cells by providing sugars generated in photosynthesis – it has been demonstrated that the animals can survive several months on this energy source alone. This relationship has doubtless impacted on the overall morphology of the species, which has a broad, flat dorsal surface, helping to maximise light capture, and exhibits the characteristic green colour of adult E. chlorotica as a direct result of chlorophyll uptake. 

Image courtesy of Patrick Krug.

Organelles: Anatomical components of a cell, such as the nucleus and mitochondria.