You?ve probably heard the saying, ?You are what you eat.? Of course you don?t become a cow when you eat a hamburger, but you do draw your energy from the energy in the food you consume. All organisms are linked together by the food chain, which illustrates the transfer of energy from one organism to another. A bird gains strength from devouring a frog, which may have eaten a fly, which may have eaten rotten fruit. Science writers Alvin and Virginia Silverstein and Laura Silverstein Nunn describe the many sources of energy we often take for granted every time we eat. The authors also explore relationships in nature and what happens when a part of the food chain is affected by toxic chemicals, foreign species, or nuclear radiation. Finally, they offer ideas for how we can protect our environment and each level of the food chain to maintain its delicate balance.