Why don't animal cells have a cell wall?
plant cells have cell walls because these cell walls are made up of cellulose and provide protectition for the plant cells. Animal cells don't have cell walls because the cell walls are made up of phospholipid bilayers and proteins. Even though the animal cells' don't have cell wall for protection, but it has endoskeletons and exoskeletons that can protect the cells as well. As a matter of fact, this is why animals are more flexible than plant cells because lack of the cell walls.
hope this helps