A new study estimates there are 20 quadrillion individual ants across the globe, which together weigh more than all wild birds and mammals combined
19 September 2022
About 20 quadrillion ants are crawling over Earth, according to a new estimate.
“Anyone who’s looked at ants and realised there are lots of them has probably wondered how many there may be in total – it’s just a question that’s on people’s minds,” says Patrick Schultheiss at the University of Hong Kong, who co-led the study with his colleague Sabine Nooten at the Julius Maximilian University of Würzburg in Germany.
To provide an answer, they compiled data from 489 studies that measured ant densities in different parts of the world using standardised methods. They extrapolated this data to estimate there are approximately 20,000,000,000,000,000, or 20 quadrillion, ants across the globe.
The total biomass of this global ant population – the collective weight of carbon in all the individuals – is about 12 million tonnes. This is more than wild birds and mammals combined, which have a total biomass of 2 million tonnes and 7 million tonnes, respectively. Humans, by comparison, have a total biomass of 60 million tonnes.
Previous estimates of the number of ants on Earth were “essentially educated guesses” that extrapolated from ant densities measured in one or two locations, says Schultheiss. The latest analysis aimed to be more accurate by looking at studies from all continents and written in different languages.
There are still gaps in our knowledge, however, because most ant counts have been conducted on the ground, rather than in trees or underground, says Schultheiss. Statistics from Africa and northern Asia are also limited.
There are 15,700 known species and subspecies of ants. The insects are vital to most ecosystems because of their roles in dispersing seeds, increasing nutrient availability via soil turnover and providing food for ant-eating animals.
Knowing the global ant population is important for conservation purposes, says Nooten.
“With this study, we provide a baseline for the global distribution of the number of ants and the biomass, and in the future we could do repeat studies in the same places using the same methods to see what has changed,” she says.
Journal reference: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.2201550119
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