At least among more complex organisms, I cannot think of any examples of highly mobile species (like animals) that also incorporate photosynthesis. Perhaps there are examples that I'm unaware of, but even so it seems to be exceedingly rare.
Is there some good reason for this, or is it a mere chance of evolution?
I could speculate, perhaps, in that photosynthesis just doesn't provide enough energy for the relatively high metabolism of mobile species; but even then, there seems there should be a "sweet spot" where some level of mobility would still be "worth it" for a photosynthesizing species, rather than the strict dichotomy that seems to be observable, so I naïvely find that explanation somewhat dissatisfactory. There just seems to be little reason for animals to not practice photosynthesis, if only to be able to eat less than they need to without it.