Reading the comments here, there seem to be two issues entangled. One is which organisms are capable of suffering (which is probably roughly the same set that is capable of experiencing qualia; we might call this the set of sentient beings). The other is which entities we would care about and perhaps try to help.

I don't think the second question is really relevant here. It is not the issue Tiiba is trying to raise. If you're a selfish bastard, or a saintly altruist, fine. That doesn't matter. What matters is what constitutes a sentient being which can experience suffering and similar sensations.

Let us try to devote our attention to this question, and not the issue of what our personal policies are towards helping other people.