What is the original source of energy for all animals in food web?

The original source of energy for all animals in a food web is the sun. Plants use sunlight to convert water and carbon dioxide into glucose and oxygen through the process of photosynthesis. This glucose is then used by plants for growth and reproduction, and it also serves as the primary energy source for herbivores. Herbivores, in turn, are consumed by carnivores, and the energy stored in their tissues is transferred to the carnivores. This process of energy transfer continues up the food web, with each level relying on the energy stored in the level below. Ultimately, all of the energy in a food web can be traced back to the sun.