Emerald elysia, http://en.wikipedia.org/wiki/Elysia_chlorotica Spotted salamander, http://www.nature.com/news/2010/100730/full/news.2010.384.html And the pea aphid, http://www.huffingtonpost.com/2012/08/21/pea-aphids-photosynthesis_n_1819615.html What they all have in common is the ability to use plant genes to photosynthesize their own nutrients instead of relying only on food resources. Only these 3 animals, as far as we know, are able to do this. To me that begs the question, why only 3 animals when every single plant on the planet can pull it off? Seems like solar energy is a pretty obvious energy source in nature yet nearly all animals are reliant on plants or animals that eat plants for their nutrients. Why would god only gift these 3 lowly critters with the ability to use photosynthesis when all other animals can't?