The single-celled protozoan ancestors of animals had their weight supported by water and were able to move by cilia or other simple organelles. The evolution of large and more complex organisms (animals) necessitated the development of support and locomotion systems. Animals use their muscular and skeletal systems for support, locomotion, and maintaining their shape.
Types of Skeletal Systems Movement is a major characteristic of animals. This movement is a result of contraction of muscles. The skeleton helps transmit that movement. …
