Have you seen how fish are able to swim in a school so precisely relating to their fish-fellows and never clumsily bump into one another? That's because they have a highly developed sense of feeling in their bodies, which enables them to feel not only the movement of the water against their skin but the presence of other beings who are close. They certainly are not cold-blooded in the sense that they are dull, insensitive, and have no feelings.
Yes, all of life is sacred, including plants; and yes, there is research that demonstrates that plants have feelings - they feel it when their leaves or stems are ripped - and there is scientific evidence that while plants do not have brains and nervous systems like animals, they nevertheless actively work to ensure their survival - they want to live, thrive, reproduce, evolve.