How many species do we share our planet with?
It's such a basic, fundamental question to understanding the world around us. Some researchers have even mused that it would be among the first questions visitors from another planet would ask us.
It's almost unthinkable that we would not know this number, or at least have a good estimate. But the truth is, it's a question where the world’s taxonomists produce very different estimates.
An important distinction is how many species we have identified and described versus how many species there actually are.
As the chart explains, we've only identified a small fraction of the world's species, so these numbers are very different.
The honest answer to the question “How many species are there?” is that we don’t really know.
by ourworldindata
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**Data source:** International Union for Conservation of Nature Red List of Threatened Species (2025)
**Tools used:** initial plotting with the OWID-Grapher; finishing in Figma
Pretty cool!
Always amazed when I am reminded how relatively rare mammals are, yet we are to a large degree the dominant type people think of. There’s 15 different arachnid species for every mammal.
A small thing: I would have liked a bar for bacteria and archea, even if we know it is only a few % that are identified and described. It annoys me that the “All Groups” bar is not equal to totalling the others. I know it says it’s selected groups, but it also says it’s the number for each taxonomic group just before that.
What defines a species is fairly subjective and depends on what animal you are looking at. There are a lot more defined species than are shown in this chart. That’s just what the IUCN red list recognise. (I gathered all of the data for and built the official world register for animals, zoobank.org)
It’s humbling to see that mammals, the group we belong to and focus on most, represent the tiniest sliver of the chart at only 6,815 species. We spend billions on conservation for mammals while there are likely millions of insects and fungi doing the heavy lifting for our entire ecosystem that we havent even bothered to name yet. It really puts our “biological ego” into perspective lol
As Robert May once said:
> To a first approximation, all species are insects