Which polysaccharide is primarily used for energy storage in animals?

Glycogen is the primary polysaccharide responsible for energy storage in animals. It is a highly branched polymer of glucose that allows for rapid mobilization of energy when needed. Glycogen is primarily stored in the liver and muscle tissues, where it can be quickly converted to glucose through a process called glycogenolysis. This response is particularly crucial during periods of increased energy demand, such as during exercise or between meals, ensuring that animals maintain sufficient energy levels for physiological functions.

In contrast, cellulose is primarily a structural polysaccharide found in plant cell walls and is not utilized for energy storage in animals. Starch is the equivalent energy storage polysaccharide in plants, while chitin serves a structural role in fungal cell walls and in the exoskeletons of arthropods, making these options unsuitable for animal energy storage.