how do worms utilize their coelom segmentation and musculatu

how do worms utilize their coelom, segmentation, and musculature (circular and longitudinal) to perform peristaltic movement?

Solution

Answer:

Worms have body walls with longitudinal and circular muscle layers. Contraction of theses muscle layers of the body wall affect the shape of the worm. Circular muscle fibres run in circles concentric to the circumference of the worm whilst longitudinal muscles run parallel to the long axis from one end of a segment to another. These muscles operate upon the liquid-filled body cavity or coelom, which acts as a pressurisable hydrostatic skeleton. When the worm contracts the circular muscles, the segments elongate and makes the worm thinner, but because liquid is essentially incompressible (and so maintains a constant volume) and the increase in pressure forces the liquid outwards, stretching the worm, so the worm becomes longer and thinner. Contraction of the longitudinal fibres shortens the worm, former the coelomic liquid out to the sides and making the worm fatter. Thus the longitudinal muscles then bring the segments back to their original shape, and these movements enable the worm to move forward.