Animals in the phylum Cnidaria, such as jellyfish and corals, exhibit radial symmetry. This means their body structure is arranged symmetrically around a central axis, allowing for equal distribution of body parts around that axis. This type of symmetry is particularly advantageous for organisms that are sessile or float in water, as it facilitates interaction with the environment from all directions. Radial symmetry enhances their ability to capture prey and respond to stimuli from various angles, which is vital for their survival in aquatic habitats.