The Collaborative International Dictionary of English v.0.48:

Snapping \Snap"ping\,
   a. & n. from Snap, v.
   [1913 Webster]

   Snapping beetle. (Zool.) See Snap beetle, under Snap.


   Snapping turtle. (Zool.)
   (a) A large and voracious aquatic turtle (Chelydra
       serpentina) common in the fresh waters of the United
       States; -- so called from its habit of seizing its prey
       by a snap of its jaws. Called also mud turtle.
   (b) See Alligator snapper, under Alligator.
       [1913 Webster]

WordNet (r) 3.0 (2006):

Chelydra serpentina
    n 1: large-headed turtle with powerful hooked jaws found in or
         near water; prone to bite [syn: common snapping turtle,
         snapper, Chelydra serpentina]