Describe the number of species found on the earth.

(N/A) According to the International Union for Conservation of Nature $(IUCN)$ $2004$ data,the total number of plant and animal species described so far is slightly more than $1.5$ million.
For many taxonomic groups,species inventories are more complete in temperate regions than in tropical countries.
Assuming that a large number of species remain undiscovered in the tropics,biologists make a statistical comparison of the temperate-tropical species richness of exhaustively studied groups (like insects) and extrapolate this ratio to other groups of animals and plants.
- This leads to a gross estimate that the total number of species on Earth ranges from $20$ to $50$ million.
- $A$ more conservative and scientifically sound estimate by Robert May places the global species diversity at about $7$ million.
More than $70\%$ of all recorded species are animals,while plants comprise no more than $22\%$ of the total.
Insects are the most species-rich taxonomic group in the animal kingdom,making up more than $70\%$ of the total animals. This means that out of every $10$ animals on Earth,$7$ are insects.
The number of fungi species in the world is more than the combined total number of species of fishes,amphibians,reptiles,and mammals.
However,biologists are still not certain about the exact diversity of prokaryotic species due to difficulties in culturing them in laboratory conditions.