ATTISH KANHAI
RESEARCH OFFICER
If I asked you to name all the living creatures you know, I am sure it would take you a couple minutes to come up with a list of several hundred, starting with your house plants, pets, to livestock and the things you may see every day like the trees in the green areas you regularly traverse. These all make up biodiversity.
But, if I were to ask how many species make up the entire planet, then the answer gets more complicated. There is no definitive answer as to the exact number of species found on planet Earth. Even the best estimates vary significantly because we have not come close to describing all the species on the planet. So how many do we actually know?
The International Union for the Conservation of Nature (IUCN) Red List tracks the number of described species and updates based on the latest works of taxonomists, biologists that group organisms into categories. Taxaonomy, however, is a field that is ever changing. When getting down to the nitty gritty of what defines a separate species in the scientific sense, things can get very messy. It is easy to differentiate between a bird and a worm for instance, however, separating different worm species is a bit more challenging. Sometimes one single species can be split into several different species due to the smallest of differences or conversely, several separate species can be combined into one.
As if this was not complicated enough, conventions on the naming of a species are also the subject of fierce debate among rival taxonomists. As it stands now, anyone can name a species, or decide which to recognise as valid and which not, there are actually no set rules. This creates issues about which list of species is valid.
I mentioned the IUCN red list earlier, however, this is not the only organisation available. The catalogue of life is another such list. A few years ago, after, shall we say, rousing debate in which one group of taxonomists may have accused the other group of being dictatorial, taxonomists drafted a set of ten principles to govern species nomenclature which they have adopted and used to govern an endorsed global list of species. This is still under review.
There is also yet another wrinkle in the answer to the question, how many species exist on Earth? Scientists are constantly discovering new species. Each year, hundreds of new species are named. In 2023 alone, researchers at the California Academy of Sciences described 153 new plant, animal and fungi species. While this may seem like a lot, given that it is estimated we have only yet described ten-20 per cent of Earth’s species, documenting all life could take centuries and, worryingly, many species may disappear from the planet before they’re even named.
Biodiversity remains under threat from major issues such as habitat loss, pollution, climate change, over exploitation of species and invasive species. The 2022 World Wildlife Fund’s Living Planet Report, found that, on average there was a 68 per cent drop in mammal, bird, fish, reptile and amp
