Animals don't perform photosynthesis ... they can't take water, oxygen, and sunlight, and mash everything together to manufacture glucose (sugar).
BUT ... that's exactly what PLANTS do ! So animals survive as long as they eat plants, OR as long as they eat other animals that eat plants.
I don't know if ya ever noticed this, but that's exactly how HUMANs survive. We eat plants, and we eat other animals that eat plants. We HAVE TO do that, or else we don't live too long.
So when you get right down to it, photosynthesis is essential to our survival !
