Ants Construct Ingenious Contraption to Keep From Drowning

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Black imported fire ants using sand to draw liquid from containers.

Black imported fire ants using sand to draw liquid from containers.
Image: Aiming Zhou/Jian Chen

A species of fire ant can turn tiny grains of sand into a powerful tool for extracting food, in a clever design meant to reduce drowning risk.

Humans, apes, crows, elephants, sea otters and other vertebrates are known tool users. Insects, not so much. Indeed, very few invertebrates have displayed this capacity, which is often taken as a sign of low intelligence. This lack-of-ability suggests bugs are inflexible, rule-based creatures incapable of thinking outside the box.

Some insects, like black imported fire ants (Solenopsis richteri), have displayed a tool-building capacity, using grains of sand as a tool while foraging for solid food. This species is native to South America, but they’ve become an invasive species in the southern U.S.

A research team led by Aiming Zhou, an associate professor at Huazhong Agricultural University in China, had a hunch that black imported fire ants can adapt their tool use in the face of risks. To test this assumption, they set up an experiment to see how the fire ants might adjust their tool use in response to foraging risks, namely an increased chance of drowning. Their results form the basis of a new study published this week in Functional Ecology.

For the experiment, the researchers filled several small bottle cap-like containers with sugar water, which is irresistible to ants. For fire ants in the wild, the equivalent food source would be nectar and honeydew, which provides them with a delicious source of carbohydrates.

All things being equal, the ants would normally dive right in and guzzle the sugar water while skimming the surface of the bath—a feat made possible by their water-resistant exoskeletons. Knowing this, and

Researchers watch ants use tools to avoid drowning

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Oct. 8 (UPI) — Scientists have observed ants using sand to draw liquid food out of containers. In addition to helping ants avoid drowning, the strategy allowed them to more efficiently collect sugar water.

Researchers described the first-of-its-kind observation in a new paper, published Thursday in the journal Functional Ecology.

When scientists first presented black imported fire ants with containers of sugar water, the ants were able to float and feed on the surface without drowning. When researchers added a surfactant, the reduced surface tensions forced the ants to adapt.

Faced with the threat of drowning, the ants collected and deposited sand grains inside the containers.

“We found the ants used sand to build a structure that could effectively draw sugar water out of the container to then to be collected,” lead study author Aiming Zhou said in a news release.

“This exceptional tool making skill not only reduced the drowning risk of ants, but also provided a larger space for them to collect sugar water,” said Zhou, an associate professor at Huazhong Agricultural University in China.

When foraging in unadulterated containers of sugar water, the ants declined to use sand or any other tools, but the addition of a surfactant changed the risk-reward calculus.

Scientists were able to trigger sophisticated tool use, as well as illuminate the ants’ ability to recognize shifts in foraging risk.

“We knew some ant species are able to use tools, particularly in collecting liquid food; however, we were surprised by such remarkable tool use displayed by black imported fire ants,” said study co-author Jian Chen.

“Our findings suggest that ants and other social insects may have considerable high cognitive capabilities for unique foraging strategies,” said Chen, a research entomologist at the USDA’s Agricultural Research Service.

Black imported fire ants, Solenopsis richteri, are native to

Ants adapt tool use to avoid drowning

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Ants adapt tool use to avoid drowning
Researchers have observed black imported fire ants using sand to draw liquid food out of containers, when faced with the risk of drowning. This is the first time this sophisticated tool use has been reported in animals. These findings are published in the British Ecological Society journal Functional Ecology. Credit: Dr Aiming Zhou and Dr Jian Chen

Researchers have observed black imported fire ants using sand to draw liquid food out of containers, when faced with the risk of drowning. This is the first time this sophisticated tool use has been reported in animals. These findings are published in the British Ecological Society journal Functional Ecology.


A laboratory experiment has shown for the first time that a species of ant has the remarkable ability to adapt its tool use. When provided with small containers of sugar water, black imported fire ants were able to float and feed on the surface, but when researchers reduced the surface tension, the ants started depositing sand grains on the inside of the container leading out of it.

“We found the ants used sand to build a structure that could effectively draw sugar water out of the container to then to be collected” said Dr. Aiming Zhou, an associate professor at Huazhong Agricultural University, Wuhan, China, and a lead author of the research. “This exceptional tool making skill not only reduced the drowning risk of ants, but also provided a larger space for them to collect sugar water.”

The sand structures were found to be so efficient that they could syphon almost half of the sugar water out of the containers in five minutes.

Researchers altered the surface tension of the sugar water by adding surfactant. When surfactant concentrations were over 0.05%, representing considerable drowning risk, ants were observed building the sand structures