Primary ProducersPlants - These are plants that make food through photosynthesis. Limited by the availability of water, they produce fewer than 200 Kilocalories of food for the animals for each square meter each year. Including:

 Trees, shrubs, cactus, wildflowers, grasses
2nd Trophic Level:

Primary Consumers

Herbivores These animals are usually small and eat little. Many are insects, or reptiles, who are cold blooded and who use less energy to maintain their bodies than mammals and birds do. As food for predators, they provide about 20 Kilocalories per square meter per year for predators. Including: Ants and other insects, rats and mice
3rd Trophic Level:

Secondary ConsumersSmall Carnivores - The

 predators are the secondary consumers. They occupy the third trophic level. Again we see cold-blooded animals, such as snakes, insect-eating lizards, and tarantualas. Only about 2 Kilocalories per square meter per year are stored in their bodies. In the harsher desert environments, they are the top predators.
4th Trophic Level:

Tertiary Consumers

Carnivores - These are high level consumers, carnivores that will eat other carnivores.