Final answer:
While alive, an animal's energy is used for metabolism and life processes. When it dies and isn't eaten, the energy is gradually released into the environment as heat.
Step-by-step explanation:
While alive, an animal's energy is used for metabolism and life processes. The nutrients obtained from food are converted to ATP, which is used by cells for short-term storage and energy. Some energy is stored in the form of glycogen and triglycerides. When the animal dies and isn't eaten, the energy is gradually released into the environment as heat.