In the The Voyage of the Beagle Darwin mentions a stop in the Cape of South Africa where he observed African Elephants and rhinos. He noted that the areas supporting these large land mammals were far less richly vegetated when compared to the jungles of South America. He speculated that it was not the quantity of food that sustains such large bodies, but perhaps its caloric content.
In terms of form, the nose of the elephant is the most specialized and highly evolved in the animal kingdom. It can function as a hand, stabilizer, siphon, trumpet, flyswatter, spray hose, weapon, snorkel, monitor, or a reassuring arm.