The criteria for deciding divisions in plants are different from the criteria for deciding the sub-groups among animals because the body design of plant is different from the animals. Plants are static and remain fixed to substratum. They are autorophic, hence they can prepare their own food by the process of photosynthesis. While animals move in search of food and shelter. They are heterotrophic; hence they are directly or indirectly dependent on plants or other animals for their food. Thus, the body design of the two groups is based on the need to make their own food in case of plants and to acquire it from external source in case of animals. The other characteristics such as presence or absence of skeleton, etc. are used to make subgroups among animals.