Earthworms have two muscles which is used in locomotion. Both muscles are circular and longitudinal (inner layer of the series of muscles). The diameter of the earthworms body is reduced when the circular muscles are contracted which makes them appear to be thin. The worm appears short when the longitudinal muscles contract thus, its length is reduced.
Amphioxus on the other hand, have two unique muscle fiber types. This includes deep fibers and smaller but mitochondria-rich superficial fibers. E<span>ach of which has its own innervation.</span>
They are called ENZYMES. Enzymes speed up the rate at which the digestion process occur so that the nutrients in the food can be absorbed by the body and used for the development of the body.