Animals behave in order to satisfy needs.

Every animal, plant and human needs the primary physiological needs of water, food and shelter provided by the abiotic system.    

Organisms in the ecosystem are interdependent. Ecosystem is encompassing all the life on earth in the physical environment that supports it. In addition, an ecosystem involves both the biological (plants, animals, human beings) and non-biological (land, water, soil, and atmosphere) community which interacts as a system. More importantly, the living things are very dependent on the abiotic community since it cannot survive by itself.