It doesn't, really. Starfish are remarkable animals for their strange characteristics, but radial symmetry doesn't have significant benefit to the survival of the animal.
Symmetry does not aid the jellyfish in any significant way, it is just used to distinguish it from other organisms.
Some of them do - approximately. At a detailed level, they do not.
Box starfish has pentaradial symmetry.
A starfish has radial symmetry
Most Echinoderms have radial symmetry. Sea Urchins, Starfish, Sand Dollars, etc.
radial symmetry
radial symmetry
Radial symmetry
A starfish or a jellyfish.
Animals in the phyla Cnidaria and Echidnodermata (for example starfish and jellyfish) have radial symmetry.
Radial?? jellyfish and starfish
The most prominent animal phyla with radial symmetry are the Echinodermata (starfish and sea urchins) and the Cnidaria (jellyfish and corals).
Bilateral Symmetry - Right down an animal (Worm or fish)Radial Symmetry - Symmetry like a circle (E.g - Starfish)Asymmetrical - No symmetry
Starfish tend to have pentamerous radial symmetry. In other words, the typical starfish has five lines of symmetry throughout their body. Some species have more lines because they have more arms.