Why does an earth worm find it difficult to move on a slippery surface?

An earthworm finds it difficult to move on a slippery surface because it relies on friction between its body and the ground to propel itself. Its movement is facilitated by the contraction and relaxation of muscles in conjunction with the use of bristles called setae, which anchor into the soil. On a slippery surface, the lack of traction prevents the setae from gripping effectively, making it hard for the worm to push against the ground. As a result, it struggles to gain the necessary grip to navigate.