What limits the length of each food chain in an ecosystem?

Living organisms, eating representatives of the previous level, receive the energy stored in its cells and tissues. It spends a significant part of this energy (up to 90%) on movement, breathing, heating the body, etc. and only 10% accumulates in its body the form of proteins (muscles), fats (adipose tissue). Thus, only 10% of the energy accumulated by the previous level is transferred to the next level. This is why food chains cannot be very long.