Why is there no cell wall in animal cells?

Animal cells do not have a cell wall because they need flexibility, movement, and rapid shape changes; instead they rely on a dynamic cell membrane, an internal cytoskeleton, and an external extracellular matrix for support.

Plants, fungi, and many bacteria have rigid walls that provide shape and protection. While walls are great for resisting pressure, they also limit movement and cell division geometry. Animals evolved complex tissues—muscles, nerves, immune cells—that must bend, crawl, engulf particles, and communicate quickly. A rigid wall would block these actions. Therefore, animal cells are enclosed only by a flexible plasma membrane made of a lipid bilayer with proteins, sugars, and cholesterol.

Instead of walls, animals use a strong cytoskeleton (actin, microtubules, intermediate filaments) to support the cell from inside. They also build a protein-rich extracellular matrix (ECM) that connects cells into tissues. This setup lets tissues be tough yet flexible—think of skin stretching, the heart beating, or white blood cells chasing bacteria.

Another reason is communication and growth. Without a rigid wall, animal cells can form many types of junctions (tight junctions, desmosomes, gap junctions) and can divide in complex ways to sculpt organs during development. The trade-off is that animal cells are more vulnerable to osmotic stress, which they handle using membrane transporters and regulatory pathways.