do chameleons tongues change color??!!?

[chameleon884]

hey i was wondering if chameleons tongues change color. because when i first got my chameleon his tongue was pink, and then it went purple for a while, then light purple-ish pink color, and now its back to pink!
the inside of his mouth has always stayed pink. does this happen to all chameleons?

 

[Carlton]

It could be that the tongue color changes with the cham's temperature and metabolic rate as it is highly vascularized.

 

[bradleymarky]

my veileds tongue was pink to start with and now its a black blue colour, freaked me out at the start but its normal