Which of the following can be said about both Cnidarians and Ctenophores regarding their movement?

Cnidarians and Ctenophores share a mechanism of movement that involves the contraction of a bell-shaped structure. In Cnidarians, such as jellyfish, this bell is the medusa, which contracts to push water out, allowing the organism to move through the water. Similarly, Ctenophores, or comb jellies, have a gelatinous body that can also contract, and they utilize their ciliary bands, which beat in a coordinated fashion, to aid in movement. The contraction of the bell in both groups facilitates swimming, allowing them to navigate through their aquatic environment.

Understanding this shared technique highlights the evolutionary adaptations these organisms have developed for movement. While Cnidarians can also utilize other methods of locomotion, such as drifting with the current, the bell contraction remains a key similarity in how both groups achieve mobility in their aquatic habitats.