Here's why:

* Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to create their own food (glucose) and release oxygen as a byproduct.

* Animal cells do not have the necessary organelles (chloroplasts) to carry out photosynthesis. They obtain energy by consuming other organisms or organic matter.

So, while both plant and animal cells need energy to survive, they get it through different means.