Here's why:
* Photosynthesis: Plants, a vital component of many aquariums and terrariums, use light as the primary energy source for photosynthesis. They convert light energy into chemical energy, which is used for growth and development.
* Ecosystem Balance: Light is also essential for maintaining the overall balance of the ecosystem. It regulates the growth of algae, which is a food source for many aquatic animals. It also influences the behavior of many animals, like fish and reptiles, who rely on light for warmth and regulation of their circadian rhythm.
While other energy sources like heat, chemical energy from food, and electrical energy for filtration systems are important, light is the fundamental energy source driving the ecosystem dynamics in these enclosed environments.