For the first time, scientists have estimated how many ants live on the Earth’s surface based on 465 previous studies. The estimated total number of 20 quadrillion is about 2.5 million times greater than the number of humans – and is associated with several uncertainties, according to the research team in their study in the specialized journal “PNAS” a fluctuation range of more or less than 5 quadrillion ants. However, the actual number could be even higher as there are no valid estimates available for ants that live underground. For other habitats, the team led by researchers from the University of Hong Kong evaluated the available regional censuses and extrapolated them according to the total area of the different habitat types.
More biomass than wild birds and mammals combined
So far, there have only been much rougher estimates, which have been extrapolated to Earth’s global land mass based on small investigations of areas in England, for example, says zoologist Patrick Schultheiss, who has since moved from the Asian metropolis to the University . from Würzburg. This estimate resulted in a number of a few quadrillion ants – which is at least similar to the current result in terms of magnitude. “We had no idea what the number could be – everything was surprising,” he says. The estimated biomass of ants is greater than that of wild birds and mammals combined and amounts to about 20% of the biomass of all humans.
“Our first concern was to find out if the density of ants is the same in different regions”, explains Schultheiss, explaining the team’s motivation – this allows drawing conclusions about the importance and integration of insects in different ecosystems. About 60% of ants that live above ground live in tropical forests; the number of ants per area is higher there than on the steppes, for example, but lower in parkland landscapes. It was already known that the number of ant species in the tropics is higher, says Schultheiss.
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Still large gaps in knowledge
It is also important that with the review the team has determined for which regions of the world there are studies on the ant populations that occur in each case. There are many surveys for southern Africa, but not for the northernmost regions of the continent. In total, the team was able to draw on around 1,300 local censuses around the world. “We hope the study will encourage people to collect data,” says Schultheiss. Datasets on regional occurrences are extremely important and allow conclusions to be drawn about what ants can do.
“Filling in the remaining knowledge gaps is of utmost importance to obtain a comprehensive picture of insect diversity – and a global understanding of the world’s patterns of biodiversity and their drivers,” the team writes in their paper. “As a global community, we must focus our efforts on the regions, habitats and regional communities we know the least about – while we still can.”