Question

How many living species have been described so far?
A. 12 million
B. 8 million
C. 8.7 million
D. 2 million

Answer 1

Hint: The full number of living species incorporates the overall number of plants and animal species. In other words, it is the entirety of combined differences at all levels of natural association. Almost seventy percent of all species recorded are animals. It is said that the plants involve no more than twenty-two percent of the whole species.

Complete answer:
In 2004, IUCN stated that the total number of species is slightly more than 1.5 million. According to the Census of Marine Life, the new total number of plants and animal species on planet Earth evaluated till now is around 8.7 million which includes both prokaryotic and eukaryotic species. It is hard to give out the exact number of existing species on Earth as new numbers of species are added every year to the discovery. Among animals, insects are the most species-rich taxonomic group making up more than 70 percent of the total. It is also estimated that the total number of fungi species is far more than the combined total of the different species of fishes, amphibians, reptiles and mammals.

Therefore the correct option is (C) 8.7 million.

Note: Even after multiple studies and discoveries, it is assumed that only 15 percent of overall species are discovered the rest are yet to be found. The undiscovered species includes 86 percent of land species and 91 percent of marine species of total flora and fauna. The estimation of 8.7 million species is based on the pattern of already known species number i.e. the number of species that are currently catalogued at different levels of biological classification.