Extinctions of unknown species

[Bert]

We often hear on nature documentaries that X number of species are going extinct every day (or year). Does anybody list them? WE also hear that there are thoudands of species that have not yet been identified. How does anybody come up with a number for that? Finally, I am sure I have heard that Y number of species are going extict every day before they heve been identified. How on earth do they come up with a figure for that?

[wildwood]

I presume it is all a bit of conjecture. Many nature documentaries are made solely for financial reasons and it does impress to quote numbers.
Having said that, there is no doubt that new species are being identified regularly, but they are mainly insects or smaller life. Some species are extremely localised within a few kilometers. It is a time consuming and costly task to categorise species. On the whole, discovering all the species of life on Earth has a low priority, but really, it is important in that the demise or reduction of species is a good indicator of the state of the ecology.