He was actually gently lowered to the bottom by wire ropes. During editing the wire ropes were erased and the scene was accelerated. While being lowered, the sharptooth also moved about in slow motion (he had to learn tai chi to learn to move so slowly), so when all was edited and sped up we got a realistic depiction of a fall.
How has Swooper managed to survive blind in a cave and only with that wormy small vine around?