1. All animals except sponges have , groups of cells that work together to perform a specific function. 2. All animals eat other organisms in order to gain building materials for the body. This makes them , since they obtain necessary energy and chemical building blocks from the environment. 3. One key adaptation of animals was the evolution of a(n) , a fluid-filled gap between the outer wall of the body and the outer wall of the digestive system. 4. All animals are , organisms with cells that are relatively large, complex, and contain membrane-enclosed organelles such as the nucleus. 5. Cnidarians are the only animal phylum to display , meaning that their bodies can be divided any way through the center point to yield two even halves. All other adult animals display , meaning that their bodies can only be sliced lengthwise through the midline to produce two even halves.