MUSCULAR AND SKELETAL SYSTEMS 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 …showed first 75 words of 2233 total…

…showed last 75 words of 2233 total…electric organs consisting of modified muscles known as electroplates. The South American electric eel has more than 6000 plates arranged into 70 columns. Maximum discharge is 100 watts. Interaction of the Two Systems Vertebrates move by application of the principles of the lever. Levers amplify or increase the force or velocity of motion. The amount of amplification depends on the length of the lever. There are three types of skeletal system; all interact with muscles using the lever.