It allows the animal to undergo rapid, purposeful movement in any direction.
Explanation:
The radial symmetry allows the animal to have a more controlled displacement, this advantage is evidenced in the response to predators which is faster than an animal with bilateral symmetry.
Also predators know its preys so they usually don't get confuse about their shape. No necessarily for having a radial symmetry the animal gets food from all sides ( the seastars have radial symmetry but the movement of their extremities do not allow them to get food from every place around). And sensing the environment is not necesarily an advantage because it don't let you know what is above you.
So an advantage of radial symmetry is the huge capacity of movement.
