Notice that the shoulder and hip bones are much larger and stronger in the frog (left) skeleton than in the perch (right) skeleton. Why do you suppose this is

To kill bacteria from our body especially from stomach

It depends on the surface of the levels. the rougher the surface, the greater is the frictional force. for rougher surfaces, you would need to exert greater force to move the object. the concept is that, you must overcome the frictional force in order to bring the object into motion. this is the reason why we add lubricants to the joints so they could easily move. this answer was on