What do animals primarily use to convert biomass into energy?

Animals primarily use oxygen to convert biomass into energy through the process of cellular respiration. This process takes place in their cells, where oxygen is used to break down glucose and other organic molecules derived from consumed food. The breakdown of these molecules releases energy, which is essential for maintaining bodily functions, growth, and overall activity.

In contrast, photosynthesis, which is the process involved in converting light energy into chemical energy, is primarily used by plants, algae, and some bacteria. Water is essential for life and also plays a role in various biological processes, but it does not directly convert biomass into energy in animals. Heat from the sun is significant for plant life and influences climate, but animals depend on consuming organic material and utilizing oxygen, rather than relying on solar energy directly. Thus, oxygen is the key component that allows animals to efficiently convert the energy stored in biomass into a usable form.