Ants Construct Ingenious Contraption to Keep From Drowning
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