As water is pushed in one direction, the jellyfish moves in the opposite direction. In addition to swimming, jellyfish are also carried by wind, waves, and currents. Ctenophora The Ctenophores, or comb jellies, are often mistaken for jellyfish due to their clear, jelly-like bodies. In fact, at one time the comb jellies were included in the same phylum as Cnidarians. However, upon closer inspection, it is evident that there are distinct differences.
Comb jellies are all free swimming and never go through alternation of generations as jellyfish do.
There are approximately 100 known species of Ctenophores and all are restricted to marine environments. Lacking the bell that is present in most jellyfish, comb jellies rely on eight rows of cilia for locomotion. The name ctenophore comes from the Greek word for comb, cteno, referring to the rows or combs of cilia in the animal. The cilia wave in unison, enabling the comb jellies to move. Ctenophores are the largest animals that use cilia for locomotion.