AFAIK, there are no animals or plants or even viuses on Earth that have DNA made from anything other than Adenosine, Cysteine, Guanine, and Thymine.
So any argument about "species" is kind of lame and has no meaning.
Life on earth is based on the above. Any proteins or amino acid complexes that are different are ruthlessly attacked.
Perhaps we are a bit too proud of ourselves. Something like 90% of living beings on earth are too small to be seen by the naked eye, they are bacteria.
And 80% of those live undeground or in the oceans.
I would say we aren't nearly proud enough of ourselves. My prediction is that that will change within 10,000 years.. Prove me wrong! =)
Exactly.