Threats of extinction

This letter I sent to Deccan Herald. Even if it is not published, the editor may read it. That will serve my purpose.
Sir,
The Edit’s (Threats of extinction, Nov.23) concern about preserving earth’s biodiversity may be shared by many, but it may not carry conviction as its facts are doubtful. One instance is the claim that one in four of all species on earth is facing extinction. So far only about two million species have been catalogued, of which, according to a World Conservation Union study reported by the BBC in Nov. 2004, only 15,589 species are threatened with extinction. This is only about one in one hundred and twenty.
Furthermore, while the species known now are only of the already explored habitats, about two thirds of earth’s habitat, the deep-sea or ‘benthos’, remain unexplored. How many species live there is a guess that varies wildly between 10 million and 100 million. With such a scrappy knowledge about even the size of earth's biodiversity, let alone their symbiosis, it is hazardous to generalize that all flora and fauna on the “entire earth are interconnected in the web of life”.
Lastly, the “balance of life”, lost when dinosaurs and thousands of other life forms perished but “replaced” after about 30 million years that the Edit refers to, is a romantic notion, not a scientific fact.