I suppose all animal life is dependent on other life for survival. It depends on your ability to dull your sensibilities.
I think the most independent forms of life are the terrestrial forms of
cyanobacteria. All they need to live are sunlight, water, atmospheric nitrogen, and a few minerals from dust. Even plants depend on bacteria to fix nitrogen.
I believe that everything is fair game. Humans are subjected to fatal attacks of fungi, viruses, bacteria, various parasites, and biting insects, and many animals would kill us for food if they could. Now, I would prefer that we not kill and eat some species – whales, songbirds, and turtles, for example – but I can't think of any objective reason not to.
Death is essential for life survival. If you aren't killing animals you are killing vegetables. Nature has no provable preference. I can have a loving relation with a pig or chicken and then eat of the species the same day. My conscience doesn't like it but it allows me to do that anyway.
Christ said, "Let no man be condemned for what he eats".
