Cell walls are a rigid outer layer found in plant cells, fungi, bacteria, and some protists. They provide structural support and protection.

Here are the reasons why animal cells do not need a cell wall:

* Flexibility and movement: Animal cells need to be flexible and move around. A rigid cell wall would restrict their movement and prevent them from changing shape.

* Internal support: Animal cells have an internal cytoskeleton that provides structural support and allows for movement within the cell.

* Cell signaling: Cell walls can hinder communication between cells. Animal cells rely on complex signaling mechanisms that require direct contact between cells.

* Endocytosis and exocytosis: Animal cells use processes like endocytosis (taking in material) and exocytosis (releasing material) to transport substances across their membranes. A rigid cell wall would make these processes difficult.

Instead of a cell wall, animal cells have a cell membrane which provides a barrier between the cell's internal environment and the external environment. The cell membrane is flexible and selectively permeable, allowing certain molecules to pass through while keeping others out.