Why does a food chain have five or fewer links?

A food chain typically has five or fewer links due to energy loss at each trophic level, as described by the 10% rule, where only about 10% of the energy from one level is transferred to the next. This inefficiency limits the number of trophic levels that can be sustained, as there is not enough energy to support a large number of consumers at higher levels. Additionally, longer food chains become more complex and less stable, making ecosystems more vulnerable to disruptions.