Question

Most natural food chains are only four or five links long, rarely more. the number of trophic levels is limited because

Answer 1

You lose energy with each tropic level. Going higher than four or five wouldn't be sustainable because there is too much energy loss when it reaches that high (when calculating energy dock off a zero: if a plant is 2000 then the creature that eats it will only get 200, then the next one would get 20.)