Yes you need one.
I’m spread too thin to give it any time right now. Great instrument here’s the link:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3702897623&category=624
Doc
Is that bamboo part that is where I would expect the reed to be the cap or is the mouthpiece really THAT huge? 
That’s the cap. The mouthpiece is pretty huge, still, but it works. The whole thing is, inexplicably, carved from one single piece of bamboo. Beautiful work.
It uses a tenor reed, but plays at about soprano pitch. About 2 octaves, almost fully chromatic. OK, fully chromatic if you cheat on the high F#. Sounds a lot like a sax, really.