Do you agree with Richard Dawkins?

[mediamogul]

You mean a plant that can suffer in the way you do? How do you know definitively that plants can't suffer, and why is sentience where you draw the line?

That's a bit of a loaded question. We are fairly sure of knowing that certain things can suffer. It's the same type of argument against the existence of god. What about a plant would lead us to believe that it was conscious of capable of suffering. We have very good reasons to believe that this with comparable nervous systems to us are capable of suffering.

Because sentience means consciousness and the ability to suffer. Suffering is self-defined as an undesirable state to each organism capable of it. It is based upon the nature of the organism. Happiness is self defined as a desireable state. Each sentient being has the right to be free from uneccessary suffering and the right to reasonably pursue its own happiness provided it does not impinge upon another's rights to be free from suffering and to pursue their own happiness.

Where else would we draw the line? The nature of the organism in question must be the foundational consideration for ethics.