- It allows for more extensive growth of the organs such as the digestive tract
- Permits contact between endoderm and mesoderm so that tissues can interact during development ex: permis parts of digestive tract to specialize certain regions.
- Permits the formation of an efficient circulatory system with a heart that can drive blood through the vessels without being restricted by a compact body
- Fluid can act as a hydrostatic skeleton. ex: in annelids for movement
- Muscles of digestive system can become independent of muscles o the body wall permitting more variation moveement
- Body movements are much less restricted and allowed the animal to be more flexible