Warning: The content of this post might cause discomfort so please view this on your own will. :)
I saw this beautiful (but lazy) green iguana as we were walking on the walkway, and as I photo shooting it it didn't even bother to move, it actually fell asleep later!
What make me sad was when I see it's tail! (Geez, I still can't get over it, while writing this I myself not looking at the picture!)
I supposed they don't sense a thing at their tail.. here some excerpt from Wikipedia:
Green iguanas possess a row of spines along their backs and along their tails which helps to protect them from predators. Their whiplike tails can be used to deliver painful strikes and like many other lizards, when grabbed by the tail, the iguana can allow it to break, so it can escape and eventually regrow a new one. In addition, iguanas have well developed dewlaps which helps regulate their body temperature. It is also used in courtships and displays.
So after all it's not feeling painful - phew! :D