WASHINGTON: The world population is expected to exceed 8 billion in the coming months. Compared to ants, that’s a moderate milestone.
Researchers have made the most thorough assessment yet of the global population of ants — insects colonized almost everywhere on the planet — and the estimated total is a staggering 20 quadrillion of those, or about 2.5 million for each human.
It should come as no surprise when you consider how ubiquitous these busy and social insects are and the fact that they have thrived since the age of dinosaurs, with the oldest known ant fossil dating back about 100 million years to the Cretaceous Period.
“Ants certainly play a very central role in almost every terrestrial ecosystem,” said entomologist Patrick Schultheiss of the University of Würzburg in Germany and the University of Hong Kong, co-lead author of the study published this week in the journal Proceedings of the National Academy of Sciences.
“They are very important for the nutrient cycle, degradation processes, the dispersal of plant seeds and the disturbance of the soil. Ants are also a very diverse group of insects, with the different species fulfilling a wide range of functions. But it is mainly their high abundance that makes they are important environmental players,” Schultheiss said.
More than 12,000 species of ants are known, which are generally black, brown or red in color and possess bodies segmented into three parts. Ranging in size from about four-hundredths of an inch (1 mm) to about 1.2 inches (3 cm) in length, ants typically inhabit soil, leaf litter or rotting plants — and sometimes human kitchens.
Ants, whose closest relatives are bees and wasps, are native to almost everywhere on Earth, as every picnicker knows, except Antarctica, Greenland, Iceland, and some island states.
“I was surprised that the biomass of ants was higher than that of wild mammals and birds combined, reaching 20 percent of human biomass. That gives you an idea of the magnitude of their impact,” said insect ecologist and researcher. co-lead author Sabine Nooten, also of the University of Würzburg and the University of Hong Kong.
“I find the sheer diversity of ants fascinating. They can be small or huge and show the most bizarre adaptations,” Nooten added, citing a widespread ant genus called Strumigenys, known for its long, spiked mouthparts used to sniff at. to hunt small invertebrates.
The researchers based their analysis on 489 studies of ant populations across every continent where ants live.
“Our dataset represents a massive collection effort from thousands of scientists. We were then able to extrapolate the number of ants for different regions of the world and estimate their total global numbers and biomass,” Schultheiss said.
Tropical regions were found to harbor far more ants than other regions, with forests and arid areas having more ants than urban areas.
“There are certain parts of the world where we have little data and we can’t make reliable estimates for all continents. Africa is one such example. We’ve known for a long time that it’s a very ant-rich continent, but also very little studied,” said Schultheiss.
Ants generally live in colonies, sometimes numbering millions, divided into groups with different roles, such as workers, soldiers and queens. The workers, all females, care for the larger queen and her offspring, maintain the nest and forage for food. Males mate with queens and then die.
“Some ants can certainly be really annoying, but that’s a very human-centered perspective,” Schultheiss said.
“Most ants are actually very beneficial, even for us humans,” Schultheiss added. “Think of the amount of organic matter 20 quadrillion ants transport, dispose of, recycle and eat. In fact, ants are so essential to the smooth functioning of biological processes that they can be thought of as ecosystem engineers. The late ant scientist EO Wilson once called them” the little things that run the world.'”