Why do puppies bite so much? Do you own a croco-pup? Biting (including nipping and mouthing) is a normal behavior in puppies. All puppies go through that terrible "landshark phase." Puppies use their mouths to play because they don't have dexterous fingers and hands as we do.
If we watch puppies interact, we will see how they are constantly nipping each other in play. They'll chase and bite the other puppys' legs, floppy ears and tails as they move and provide lots of interactive fun.
Play in many animals encompasses rehearsing behaviors that will later on turn handy in life. In dogs, many play behaviors mimic hunting. We can see the stalking, the chasing and the pouncing.