My RES is about 4 in. and has recently started biting at his dock and also his rock.
Not just little nibbles, I mean full on gripping and using claws to help out.
I feed him plenty and he even eats a cuttlebone, so I know he's not malnourished.
Possibly just being playful?
I also noticed that he's been drinking a lot more water today than normal.
The dock is a ZooMed basking dock and the rock is a decorative rock that he likes to climb more than the dock.
Here's a video:
http://www.youtube.com/watch?v=UKWwJqlnZUg



