Chemical energy from the food they've eaten. Ultimately that energy comes from the sun
Carbohydrates are the primary energy source for herbivores (cows, horses, etc.). Proteins are the primary energy source for carnivores (dogs, cats, etc.).
Glucose is the only energy source that the brain can use.
Carbohydrates
light energy
The greates source of energy is the Sun
protiens
Wind
solar
Wind energy.
Carbohydrates
Carbohydrates
Carbohydrates