When Michael Phelps announced his retirement at the 2016 Rio Olympics he really had no intention of swimming competitively again. However, that changed when he approached the Discovery Channel to help kick off Shark Week with a race against one of the world’s fastest and most efficient shark-a great white!

On Sunday, July 23 at 7:00 p. m., over five million viewers tuned in to watch the competition. While television viewers saw the competitors swimming side by side, in reality, Phelps raced by himself in the cold Allantic waters off of Cape Town, South Africa. The Discovery Channel film crew then inserted his computer-made competitor simulating (模拟) a real shark’s speed, which was estimated by attracting a great white with a fake seal over the same 100-meter stretch of the Allantic.

Though Phelps managed to complete the distance in an impressive 38.1 seconds, 9.41 seconds faster than his personal best of 47.51 seconds, he was no match for the great shark, which clocked 56. I seconds. Like a true champion, the fish celebrated the victory by leaping out of the water. Phelps, meanwhile, took the loss in good humor, saying: “Remaleh? Nexttime ...warmer water.”

The swimmer later said/4Honestly, the first thought that went through my head when I saw the shark, is that there’s probably very little chance for me to beat him.

While some fans were disappointed that Phelps did not race a live shark in the ocean, organizing that would have been dangerous for the swimmer. Besides, Discovery Channel’s aim in organizing the competition was to cause excitement and interest in sharks. Considering that it was the highest Shark Week special in the program’s 29-year history, they surely succeeded.

You might remember watching Tweety and Sylvester from the Looney Tunes cartoons while growing up. Every time the cat Sylvester would try to eat the bird Tweety, the latter would call its owner and complain about the cat, just as a human would. In reality, several birds are able to mimic (模仿) speech. The most common bird known to do this is the parrot.

Studies have shown that the young birds learn and memorize species-specific songs by mimicking vocalizations (发声) of their father, starting as early as a week after birth. If separated from the father during this sensitive (感觉敏锐的) period, young birds may develop very strange songs.

It is common sense that a singer with a broader vocal range (范围) will be more successful than one with a smaller vocal range. Similarly, male songbirds with the vocal learning ability to learn broader types of songs enjoy higher chances of attracting attention of female. Therefore, such songbirds started achieving broader song learning skills as time went by. Eventually, they ended up with vocal skills so broad that they could not just learn songs from other males in their species, but songs from different species too.

Parrots have been kept as pets for thousands of years, and are probably the most famous mimics. Vocal mimicry in parrots has often caught human’s attention, since they can mimic the difficult vocalizations of human speech learned from their caretakers. The reason for this is not to attract mates. Parrots raised as pets often mimic humans to establish social connections.

In a study on an African Grey parrot, scientists observed that it could not just mimic human speech, but could also learn several hundreds of words and their meanings, recognize objects by names, and even count! The study has made scientists think that parrots are not simply mimicking, but that their vocal ability is very similar to that of human speech. This is a huge discovery, as humans are the only animals known to be capable of using “language” to date.

“The ant and the zebra” sounds like the title of one of Aesop’s fables (寓言). Like all good. fables, this one has a moral, which is that human intervention in nature has unpredictable consequences. Unlike the Greek originals, though, this fable is real.

The story plays out in Laikipia county, Kenya, where the big-headed ants, an invasive (入侵的) species have gradually been replacing the native acacia ants. As Mr Kamaru, a Kenyan biologist from the University of Wyoming, and his colleagues report in Science, the an t invasion has triggered a complicated chain of consequences which has helped zebras at the expense of buffaloes, thus neatly illustrating a phenomenon called trophic cascade (营养级链).

It works like this. A kind of tree — whistling-thorn trees — provides the ants with shelter and food. The ants, meanwhile, protect the trees by seeing off the chief threat to them, the local elephants, which are not keen to eat trees, crawling with biting insects. However, big-headed ants are not so good at keeping the elephants at bay (陷入困境). The elephants move in and chew the trees, removing much of the area’s cover. That throws the local lions into confusion, which often use this cover to hide when hunting zebras. To compensate (补偿), the lions switch to hunting buffaloes, which are more dangerous, but run slower.

Mr Kamaru has put numbers to the process too. In invaded areas, elephants break trees five to seven times as often as in uninvaded ones. And in those uninvaded places, zebra kills are almost three times as frequent as those in the invaded ones. Indeed, between 2003 and 2020, as the big-headed ants spread, the proportion (比例) of local lion kills where the victim was a zebra fell from 67% to 42%. On the contrary, over the same period, the proportion of buffalo kills rose from zero to 42%. Whether the buffaloes blame the ants for their misfortune, no one knows.