A Visit to the Zoo

Yesterday, we visited the Henry Doorly zoo in Omaha, Nebraska.  It was an enjoyable visit but I really noticed one thing:  many of the herbivores and omnivores in captivity were fat, but not the predators.  The big cats were lean and lithe, but the hippopotamus, the bears, the gorillas, the wild pigs, etc. were all fat.  Many of the animals that subsisted mostly or entirely of carbohydrates were the fat animals.  Not all:  the gazelles were lean and lithe, and the fish-eating penguins had lots of body fat, but as a general rule, it fit.  I found this very curious.