'Serpent' in the Bible

and He saith, 'Cast it to the earth;' and he casteth it to the earth, and it becometh a serpent -- and Moses fleeth from its presence.

go unto Pharaoh in the morning, lo, he is going out to the water, and thou hast stood to meet him by the edge of the River, and the rod which was turned to a serpent thou dost take in thy hand,