Conservation of Species

I believe that in order to know what species need to be saved, we must first understand their place in the ecosystem. What I mean by this is that we need to know how the ecosystem will be affected if a certain species is no longer a part of it. The lack of a certain species can have a "domino affect" on an eco-system; in theory if a particular insect were to disappear another species (let's call them species A), that feeds on these insects is without a food source, species A would either die off or significantly be reduced in number. Perhaps another species (let's call them species B) feeds on species A, if species B is without a constant food source they in turn could also die off or be reduced in number.
This can seem very complicated; however it shows how important every species can be to a certain eco-system; from the lowly insects to the "dominant" humans.
Humans tend to save species that are "cute" or "adorable." We base our intentions off of the mere look of an animal. But who'd want to save a hairy tarantula? Or a slimy fish? What people don't seem to realize is that these "gross" insects and "dull" fish are important to the ecosystems that they reside in. So before we decide to save a certain species based only on their "cuteness" factor we should consider the affect of losing the other "less cute" species.
When it comes to balancing the needs of humans with that of animals, I only have one thing to say: We as human-beings need to realize that this world was not put here just for us. We are not here so we can drain this world of its resources and merely leave. We need to know that other organisms exist with us, and that they have just as any right to exist and thrive as we do.