Why do starfish have five arms?

Starfish have five arms as a part of their radial symmetry, which allows them to move, capture prey, and sense their environment efficiently. This pentaradial body structure evolved to distribute sensory and locomotive functions evenly around their bodies, enabling them to react to stimuli from any direction. While five arms are typical, some species may have more. If a starfish loses an arm, it can regenerate it over time, which is a critical survival adaptation. These arms also contain tube feet powered by a water vascular system, aiding in movement and food capture.