Surfing on the web with my keyboard, searching the forums, clicking the posts. Read through the thread to get the scoop-- Create energy? walks closer NOOO! NOOO! grabs physics books and tosses them at the post

The technical term for such a creature would be a photoheterotroph. And, yes, as someone pointed out with the hornet, it is possible, and it is present within another species of insect. The paper suggests lateral transfer is possibility as it possesses genes...you will read it. Lateral transfer during evolution is a fancy of way that fucker was genetically modified by eating plants.

As for larger creatures...hold on...type to create some shyt.

I would first imagine something near water as there are good sources of plants, bacteria, and sun. I think being around some type of water would be likely as aquatic animals usually do not have fur and fur would impede UV absorption, and I would argue the lack of fur, and thus being more likely to dessicate, would make its origins more likely near or in water.

If its origins are aquatic, it is likely not going to be a mammal. To keep things simple, let's say it is an ectotherm. That provides a neat opportunity for photosynthesis to have some function as the sun would provide not only the means for it (artifical light can do it as well) but would directly provide the animal its warmth.

Let's talk about a 'reason' why photosynthesis was selected for: maybe their young are more vulnerable during the day and thus cannot eat as well. Perhaps that photosynthesis provides them with the energy to bioluminescence at night for their young that in turn uses photosynthesis to grow. It could also have a secondary function in which it can scare away predators, which may be a confounding variable as to why their young are better off at night.

Or maybe their young are near water more often and thus are likely to be beneath a canopy, which would limit how much sunlight they receive. Either way, photosynthesis would increase their fitness.