Not many organisms can survive in this severe environment, the Sahara Desert, where daytime temperatures can reach 140 degrees Fahrenheit. But an insect called the Saharan silver ant grows well. They rush out onto the sand from their protected nests to gather up the bodies of insects that have died from the heat.

“The hotter the day, the more insect bodies they will find. The more food they have.” said Sarah Pfeffer, an animal behaviorist at Ulm University in Germany. She says that to avoid sinking into the Saharan sand, where they could meet the same fate（命运）as their lunch, silver ants have to be fast.

To document just how quickly the ants move, Pfeffer and her colleagues set up high-speed cameras above a channel between the entrance to the hungry ants’ nest and a food source. The researchers recorded top speeds approaching 35 inches per second.“But if you really look at how big the animals are and you calculate the body length per second, you will come up with a walking speed that is an astonishing 108 body-lengths per second.”That figure makes them the fastest known ant on the planet. By comparison, cheetahs(猎豹）top out at about 16 body lengths per second. The videos showed how the ants achieve such amazing speeds. As they accelerate, their leg movements become synchronized(同步). They increase their running length by bringing all six feet off the sand at once, which Pfeffer describes as a gallop. “Really all legs are lifted from the ground. They are in the air, but it’s not jumping. It’s a very smooth run that they have.”

A closely related ant called Cataglyphis fortis only reaches about 24 inches per second, or two-thirds of the silver ant's max.

The Saharan silver ants' speeds may be impressive, but two insects are even faster. The Califormia coastal mite (壁虱) and the Australian tiger beetle, both of which also grow well at near-deadly temperatures. It seems that to beat the heat, it pays to be fleet.

According to a recent study in Science, pigs are providing convincing new evidence that animals may respond emotionally to music. The finding may lead to ways to improve their welfare on farms. “It’s a really neat study that shows animals are more emotionally attuned (音感好的) to music than people think”, says Charles Snowdon, an animal behaviour expert at the University of Wisconsin.

Music is sometimes used as enrichment for animals and other captive animals. And Snowball the dancing cockatoo (凤头鹦鹉) likes to dance to the Backstreet Boys. But whether these creatures have a true emotional response to the tunes is unclear. That’s what the new study aimed to do — but with pigs. Coauthor Maria Camila Ceballos, an animal welfare scientist, says she chose these animals because they are intelligent and social, and face serious welfare challenges on factory farms.

The researchers composed music that were either consonant or dissonant. To humans, consonant music generally sounds pleasant whereas dissonance tends to sound uncomfortable. The team then filmed six litters of young pigs listening to the music, which was played in a random order with a break in between.

The researchers scored the pigs’ body language using an approach called QBA. Pieces of consonant music were linked to the pigs experiencing positive emotions, whereas the dissonant music was linked to negative emotions, the team reports this month in Scientific Reports. “So we found that, yes, music generates different emotions,” Ceballos says.

Animal welfare scientist Jun Bao from a university in China is skeptical about whether Ceballos’s team detected emotions, however. He recently found that exposure to music increases play and tail wagging in pigs, which he sees as signs of a “positive mood”. However, he says it’s not clear that pigs labeled as “happy” or “uneasy” through QBA actually experience those emotions.

Ceballos hopes the study will help researchers create welfare-improving music, tailor-made to a specific species. Bao also agrees, adding “It’s really interesting, because if it works, it would be the handiest and cheapest way to enrich their environment.”

From Smells to Soundtracks

When a young sawfly, a bee-like insect, is threatened by its attackers like ants, it emits a mixture of unpleasant smells to defend itself. These emissions can seriously annoy a potential enemy.

Scientists wanting to study these smelly compounds—to understand which aspects of them discourage attackers and why—face great challenges. Meetups between sawflies and ants in a lab are difficult to carry out. There are also a very limited quantity of the insects’ emissions. On the side, Jean-Luc Boeve, a zoologist who studies insects, from the Royal Belgian Institute of Natural Sciences, is an amateur musician and composer. He decided to try a different way—the sound approach. “To be honest, I considered this project so unpractical myself that I set it aside,” he said. It was months before Boeve and his partner, Rudi Giot, finally made a resolution to get started on it.

They chose 16 sawfly species’ emissions to translate into sounds. First, they figured out which molecules(分子) were present in each smelly compound and in what amounts. Then they assigned various characteristics of those molecules matching properties of sound. For example, smaller molecules like a kind of acid found in vinegar, a sour-tasting liquid, evaporate(挥发) quickly, so Boeve and Giot assigned them sounds with higher pitch(音高). Larger molecules were given lower-pitched sounds. In all, the scientists created individual audio descriptions for 20 molecules. Then they combined the sound of each molecule present in a sawfly’s smell to construct the insect’s soundtrack. If a molecule was of higher proportion in an emission, they assigned it a higher volume. In such a case, the smaller a molecule is, the higher its pitch will be; and the higher the proportion of a molecule is, the higher its volume will be.

To test out the audio descriptions they created, Boeve and Giot examined people’s reactions to the soundtracks and compared them to ants’ reactions to the original smells. They played the 16 emission soundtracks and the 20 molecule sounds through speakers to about 50 study participants. Then the scientists measured how far people backed up to get to a “comfortable position” away from the noise. Most of the study volunteers told the researchers that the high pitch, as well as the high volume, was what made them withdraw. “Ants and volunteers moved away from a chemical and its matching soundtrack respectively,” the researchers wrote.

Boeve said he hoped the process would give other zoologists a new way to compare sawflies’ chemical defenses with those from other insects. It may also offer researchers clues about which molecules fight off enemies most.