What is the main energy storage form in animals?

Glycogen is the primary energy storage form in animals. It serves as a vital energy reserve that can be rapidly mobilized when the body requires glucose, especially during periods of high activity or fasting. Glycogen is a polysaccharide made up of numerous glucose units linked together, allowing for efficient storage. It is primarily stored in the liver and muscles, where it can be easily converted back into glucose when energy is needed.

On the other hand, while glucose is an essential energy currency in cells, it is not stored in large quantities. Starch is a plant-based polysaccharide used for energy storage in plants, and cellulose is a structural component of plant cell walls, providing support but not serving as an energy storage molecule for animals. Therefore, glycogen is uniquely suited as the energy reservoir in animals, enabling swift energy release when necessary.