Why are the trophic chains in caves very short?

The length of the food chain in the cave is not long, because it is determined by the amount of energy transferred along the chain. at each link, energy is lost in the form of heat. The amount of energy in the chain, in turn, depends on how much chemical energy will be formed by the initial link – autotrophic organisms (plants). Plants do not generate energy themselves, but absorb it in the form of light and convert it into energy of chemical bonds. Since the level of light in caves is extremely low, less energy is accumulated.