>I thought it was organ bass pedals?

It was a little three octave Fender Rhodes Piano Bass. You can see one here:
http://www.melmusic.com.au/articles/collect10.html


Presque Isle, Maine : Why did the band not have a bass player? Did Jim
Morrison have the idea not to?

Ray Manzarek: My left hand was the bass player. I played the keyboard bass.
It sounded full and fat, big and round in concerts. "Lefty" will be mad to
hear you say we never had a bass player.

Notice he uses the word "concerts."  A lot of references to recording
indicate that they used session bass players.