Butch the Common Snapping Turtle (Chelydra serpentina) Yearling
 
 

Snapping Turtles can grow very fast in captivity when the are well fed, protected, and kept in warmer water.  Butch was about 1½ inches long when I acquired him in March 2005.  In the 8 months since then, he has grown to a shell length of 5 inches.  That's a growth rate of about 4 inches per year.  The bigger he grows, the grumpier he seems to become.  Watch those fingers!

One of the features that distinguishes the Common Snapping Turtle (above) from the Alligator Snapping Turtle is the presence of saw-like (serrated) projections from the top surface (dorsum) of the tail.  Although these give the turtle the appearance of having an alligator-like tail, they should not be confused with the Alligator Snapper, which lacks these projections.  Go figure.