An Etymological Dictionary of the German Language/krabbeln
krabbeln, vb., ‘to crawl,’ with LG. permutation, in contrast to MidHG. krappeln, of which the variant krabelen occurs, whence also earlier ModHG. krabeln. The form with a double labial may be due to its being popularly connected with Krabbe (Krappe), for in Scand. also a simple form is found without this double labial, Scand. krafla, ‘to scratch with the nails,’ and krafsa, ‘to shuffle with the feet.’ E. grabble, grapple, grab are connected with LG. and Du. grabbeln.