● Since there are published records of all the species discovered and named, we know how many species in all have been recorded so far, but it is `color{violet}("not easy to answer the question")` of how many species there are on `color{violet}("earth.")`

● According to the `color{violet}("IUCN (2004)")`, the total number of `color{violet}("plant")` and `color{violet}("animal")` species described so far is slightly more than 1.5 million, but we have no clear idea of how many species are yet to be `color{violet}("discovered")` and `color{violet}("described.")`

● Estimates vary widely and many of them are only `color{violet}("educated guesses.")`

● For many `color{violet}("taxonomic")` groups, species inventories are more complete in temperate than in `color{violet}("tropical countries.")`

● Considering that an overwhelmingly large proportion of the species waiting to be discovered are in the `color{violet}("tropics, biologists")` make a statistical comparison of the `color{violet}("temperate-tropical")` species richness of an exhaustively studied group of insects and extrapolate this `color{violet}("ratio")` to other groups of `color{violet}("animals")` and `color{violet}("plants")` to come up with a gross estimate of the `color{violet}("total number")` of species on `color{violet}("earth.")`

● Some extreme estimates range from 20 to 50 million, but a more `color{violet}("conservative")` and `color{violet}("scientifically sound")` estimate made by `color{violet}("Robert")` May places the global species diversity at about 7 million.

● Let us look at some interesting aspects about `color{violet}("earth’s biodiversity")` based on the currently available species inventories.

● More than 70 per cent of all the species recorded are `color{violet}("animals")`, while `color{violet}("plants (including algae, fungi, bryophytes, gymnosperms")` and `color{violet}("angiosperms")` ) comprise no more than 22 per cent of the total.

● Among `color{violet}("animals")`, insects are the most species-rich `color{violet}("taxonomic")` group, making up more than 70 per cent of the total.

● That means, out of every 10 animals on this planet, 7 are insects.

● The number of `color{violet}("fungi")` species in the world is more than the `color{violet}("combined total")` of the species of `color{violet}("fishes, amphibians, reptiles")` and `color{violet}("mammals.")`

● `color{violet}("Biodiversity")` is depicted showing species number of `color{violet}("major taxa.")`

● It should be noted that these estimates do not give any figures for `color{violet}("prokaryotes.")`

● `color{violet}("Biologists")` are not sure about how many `color{violet}("prokaryotic")` species there might be.

● The problem is that `color{violet}("conventional taxonomic methods")` are not suitable for `color{violet}("identifying microbial species")` and many species are simply not culturable under `color{violet}("laboratory conditions.")`

● If we accept `color{violet}("biochemical")` or `color{violet}("molecular criteria")` for delineating species for this group, then their `color{violet}("diversity")` alone might run into millions.

● Although India has only `color{violet}("2.4 per cent")` of the `color{violet}("world’s land area")`, its share of the `color{violet}("global species diversity")` is an impressive 8.1 per cent.

● That is what makes our country one of the `color{violet}("12 mega diversity")` countries of the world.

● Nearly `color{violet}("45,000 species")` of `color{violet}("plants")` and twice as many of `color{violet}("animals")` have been recorded from India.

● If we accept May’s global estimates, only `color{violet}("22 per cent")` of the total species have been recorded so far.

● Applying this proportion to India’s `color{violet}("diversity figures")`, we estimate that there are probably more than `color{violet}("1,00,000 plant")` species and more than `color{violet}("3,00, 000 animal")` species yet to be `color{violet}("discovered")` and `color{violet}("described.")`

● Questions like would the inventory of the `color{violet}("biological wealth")` of our country ever be completed and regarding the immense trained manpower (taxonomists) and the time required to complete the job `color{violet}("plague the ecologists.")`

● The situation appears more hopeless when we realise that a `color{violet}("large fraction")` of these species faces the threat of becoming extinct even before we `color{violet}("discover")` them.

● `color{violet}("Nature’s biological library")` is burning even before we catalogued the titles of all the books stocked there.