cicerone imposter wrote:I once thought (sun) light was a necessary component of life.
In most cases it is the driving force to life on this planet. But there are exceptions (geothermal vents hosting lightless environments, and deep badrock bacteria subsisting on water and chemicals filtering through the rock). And caves are not sealed environments in most cases. Food items, or bacteria subsisting from external sources, find their ways into caves and are consumed.
In the most simplistic sense, energy is a necessary component of life. Energy in the form of sunlight is common and accessible through photosynthesis. Energy in the form of heat is available from geothermal sources. But energy is also available in the form of food (which is essentially chemical energy (sugars which are formed in photosynthesis)).
In cave environments food from the outside usually finds its way into the cave environment. Animals come and go from the cave, and water containing bacteria seep through the rocks. Most cave creatures live off of each other, and from the various food items which find their way into the caves.
