Answer:
1. Tissues
2. Heterotrophic
3. Body cavity
4. Eukaryotes
5. Radial symmetry; bilateral symmetry.
Explanation:
1. All animals except sponges have tissues, groups of cells that work together to perform a specific function.
Sponges are sea animals which are found attached to surfaces. They are multicellular and heterotrophic like other animals, but they lack true tissues and organs.
2. All animals eat other organisms in order to gain building materials for the body. This makes them heterotrophic, since they obtain necessary energy and chemical building blocks from the environment.
Heterotrophs are organisms that cannot manufacture their own food, but obtain it from their environment instead.
3. One key adaptation of animals was the evolution of a body cavity, a fluid-filled gap between the outer wall of the body and the outer wall of the digestive system.
A body cavity is a space found inside the body that is filled with fluid and which holds and protects internal organs. There are several cavities found in the human body and they are separated by membranes as well as many other structures.
4. All animals are eukaryotes, 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 radial symmetry, meaning that their bodies can be divided any way through the center point to yield two even halves.All other adult animals display bilateral symmetry, meaning that their bodies can only be sliced lengthwise through the midline to produce two even halves.
