Which animal organ system is responsible for extracting energy from the environment?

The digestive system is responsible for extracting energy from the environment in animals. It breaks down food into nutrients, which are then absorbed into the bloodstream and utilized by the body for energy. This process involves various organs, including the stomach, intestines, and accessory organs like the liver and pancreas. Overall, the digestive system plays a crucial role in converting food into usable energy for growth and metabolic functions.