I caught one someday. Measured it first from its tail to head, got 6 meters; then from head to tail... astonishing result was 5 mtrs. That's because I was afraid of its teeth :)
Had not seen "tubarao" before, sorry about not putting the thingy on top of the "a", also, could anyone tell me what that thingy is called in english and in portuguese?
In English the symbol is called a tilda. It can be found on most American keyboards on the top row to the left. Someone else will have to help with the Portuguese term.