What is the function of the ventral surfaceof a worm?

The ventral surface of a worm is the underside that typically faces the substrate it moves on. It plays a crucial role in locomotion by allowing the worm to anchor itself and push against the ground as it contracts and expands its body segments. This surface is often equipped with setae, small bristle-like structures, which aid in gripping the soil and enhancing movement. Additionally, the ventral surface may help with moisture absorption and protection from environmental factors.