I have never payed attention to their behavior. but thanks for pointing that out I went there in the evening (of the one day they are open until 9pm) so maybe it was really tired. and in its tank there are no threats so it doesn't need to be careful.
haha while shooting I get so active I always forget to look at the animals' names so I had to look it up quickly. It is called giant girdled lizard (Cordylus giganteus) although they are not that big at all - my estimation is they're around 25-30cm long.