ช้วยแปลประโยคนี้ให้หน่อยค่ะ

Snails and slugs move by contracting and relaxing muscles in the foot. There are two sets of muscle fibers,each performs a different task. When moving forward one set contracts pulling the snail from the front and pushing it off toward the back.At the same time the second set pulls the outer surface of the sole forward. Both halves can move seperatly, creating a sort of locomotion called reptation.