In the latter case the resistance is caused by dissipation of mechanical energy when the configuration or the direction of flow is sharply changed, by the formation of vortices and secondary flows as a result of the flow breaking away, by the centrifugal forces, etc.
Animals depend on plants for food as plants produce food and energy which animals can't, so, herbivores eat plants to get energy, carnivores eat herbivores and other carnivores for energy and omnivores eat all four, plants, herbivores, carnivores and also other omnivores for energy.
The names depend mostly on what the organism eats and how it contributes to the energy of the ecosystem. 1  Producers - Plants are producers. 2  Consumers - Animals are consumers. 3  Decomposers - Decomposers eat decaying matter (like dead plants and animals).