I know that when lesser daedra's physical forms are destroyed, they are cast back into oblivion; however my question is, what classifies as 'destroyed'? Obviously, removing said daedroth's head, or disintegrating their body would do it; but what biological requirements does their body have to meet for their physical form to keep living? Would they require their "organs" to be functioning? Would they require mundane things, such as breathing or eating to maintain their physical form? (At least while in the mundus; while in their respective planes of Oblivion, I doubt it matters.)
What do you think? I myself wouldn't count on them requiring food or drink; but I do think that at least in certain ones, such as dremora, you could cause them to bleed to death with a large enough wound; implying that they require that blood...