Nutrition: food being taken in, taken apart, and taken up. When an organism"s muscles and other organs will be chewed into pieces, broken down by acid and enzymes in their digestive system and then it is absorbed as small molecules into the body. Unlike plants, most animals eat other organisms dead or alive, piecemeal or whole: animals must consume food for both energy and the organic molecules used to assemble new molecules, cells, and tissues, animals have diverse diets. Herbivores: dine mainly on plants and algae, ex: cattle, sea slugs, and caterpillars. Carnivores: mostly eat other animals, ex: sea otters, hawks, and spiders. Omnivores: don"t eat everything, but they consume animals as well as plants or algae, ex: humans, cockroaches, and crows. Animals must eat: to survive and reproduce, they must also balance their consumption, storage, and use of food. 41. 1: an animal"s diet must supply chemical energy, organic molecules, and essential nutrients.