Because suppose that sun have 1 lakh joule energy then plant will get only1% that is 1000then deer will get 100 joule and loin eat it and get 10 joule then lion eat him the next day then he get 1 joule energy .therefore loin is getting the remaining energy of deer for 3 days after this energy level become so low that lion can't survive on it. hope this will help you
How can he survive on such a low amount of energy when even a deer requires more?? The digestion process in lion will take more energy than that in deer. Plus it has to spend a lot of amount of energy for hunting. I dont think 10Joules is enough for that.