1. of, relating to, or situated on the side of a radially symmetrical animal (such as a starfish or sea anemone) that bears the mouth
Usage: biology; zoology

Examples

• The actinal surface of the starfish contains the mouth and tube feet used for feeding.
• Sea anemones have their tentacles arranged around the actinal pole.
• In echinoderms, the actinal side is typically the ventral or lower surface.
• The actinal region of the sea urchin is where the mouth is located.