An interesting talk by philosopher Peter Godfrey-Smith (Sydney) at IAITV, especially the last twenty minutes (after some initial stage-setting, much of the first ten minutes was given over to what I found a rather unsatisfying discussion of meta-ethical questions, but tastes may vary!).   Crustaceans are sentient, insects probably are, plants are probably not.  But what if we dropped sentience as the sole consideration of moral relevance, and asked about "well-being" regardless of conscious experience, perhaps, in terms of "health" or "preferences"?  That would get plants, bacteria, indeed all cellular life into the circle of moral concern.   To be clear, Godfrey-Smith does not treat that as a reductio of the position, although one could imagine someone going that route. Anyway, I found that discussion interesting and, as one would expect, empirically well-informed.