Predict How might an animal's ability to move change if its backbone were rigid like a metal tube?

Its movements would depend entirely on joints on the limbs, like most robots. It would be more difficult to share the body's weight and vertical acceleration loads among the limbs. and without spinal flexibility the impact loads would be much worse. Different gaits (e.g., a horse's walk, canter, trot and gallop) would be difficult since spine motion can ist in implementing fore-and-aft limb motion differences.