Q. What are the two major morphological patterns of cnidarians? Concerning locomotion how do these forms differentiate from each other?
Morphologically, cnidarians classify as medusae or polyps. Medusae are circular convex, like an umbrella and Polyps are cylindrical. Both of the shapes have tentacles.
In general polyps are sessile but some species like hydra can move by performing somersaults and by alternating contact points on the substrate. Medusae can move about expelling water jets by contraction of the body.
A few cnidarians alternate a medusoid and polypoid forms in their life cycle.