Shunryu Suzuki said,
"If you are not a Buddhist, you think there are Buddhists and non-Buddhists, but if you are a Buddhist you realize everyone's a Buddhist—even the bugs."
I've enjoyed the sentiment of inclusiveness in that quote.
Today I find Suzuki's remark a little Buddhocentric. (Is "Buddhocentric" a word?) Whatever: we can say bugs are sentient beings, yes they are. Bugs have "Buddha nature" and so do all the bacteria that live inside bugs' digestive systems.
Plants have have sentience so deep and so powerful and so profound that their multiple intelligences are barely discernible to any but the most spiritually connected humans. Plants have "Buddha nature" too. Not to mention fungi.
I've come to feel that all of life—from the mitochondria in cells to blue whales to the daffodils awakening outside my front door—all life is deeply and irrevocably interrelated. All life is sentient. All life is sacred. Even stuff we think of as not living is sentient: rocks, water, air. I think rocks know when they're hot or cold. Water freezes when it gets cold; evaporates quickly on hot days. Sentient.
We can say this or that has Buddha nature. Better yet, we give the Buddha some time off. I don't think he wants to lay claim or put his name on wisdom that is self evident to anyone willing to look closely and feel deeply about anything and everything alive.