Magawa was born in Tanzania in 2014 , and he's a little bigger than normal rats. Magawa and several other rats are part of the " Hero Rat " program run by a group called APOPO. Because the rats are so light , there's little danger that they will cause accidents while working.

From a young age he was trained to sniff out TNT( 炸药). The training normally takes about a year. Magawa's main job is to sniff out a trickier kind of bomb, known as a mine which is hidden,usually underground. In Cambodia , where Magawa works , mines were common during long periods of civil war between 1975 and 1988. During that time , around 5 million mines were planted in the country. About half of Cambodia's minefields haven't yet been cleared. Since 1979 , these mines have killed or injured over 64 ,000 people.

Magawa is taken out to a minefield, which he carefully goes over , section by section. Magawa's master , Malen , guides him carefully across the field on a leash( 绳子 ). When Magawa finds a mine,he scratches at the dirt above it , wigwagging that he's found something.

Because the rats work by sniffing , they're very fast. It only takes Magawa 30 minutes to search an area as big as a tennis court. A human doing the same job would take four days. Malen says that Magawa and his colleagues are very confident in the field. He works quickly and is easily able to make decisions about whether something is a danger or not. Magawa is the star sniffer of the Hero Rat program. He's found 39 landmines and 28 bombs that were dropped from planes , but never exploded.

To honor Magawa , the PDSA made a special gold award that was small enough for Magawa to wear.

Spiders don’t have ears like we do, and many have poor eyesight. But they can sense vibrations (振动). Instead of eardrums that turn soundwave pressure into signals for our brains, spiders hear using tiny, sensitive hairs that move in response to sounds.

Previously, researchers had measured how a single thin piece of spider silk moved in response to sounds in the air. They found that the web silk itself is really good at detecting sounds. In a new study, Ron Miles from Binghamton University and his co-authors provided the first evidence that spiders can pick up sounds in another way through their webs.

To study hearing in animals, researchers placed orb-weaving spiders, which are known to make large, wheel-shaped orb webs, in a specially designed quiet room. They tracked how the spiders reacted to different sounds played on a loudspeaker Depending on how loud the sound was, spiders stretched, turned or raised their forelegs. Researchers noticed that the spiders turned their bodies toward the sound, suggesting they knew where the noise originated.

The ability to use a web like a giant extended ear could help spiders detect prey (猎物). If an insect is flying nearby, for instance, “That’s going to cause the web to vibrate because of the sound,” Miles said “That kind of gets the spider’s attention.”

Spiders might even use their webs to tune in to a variety of sounds “We suspect that the spider is actually able to sort of adjust the tension in the web in order to pick up certain frequencies,” Miles said.

Most microphones today work by sensing pressure and turning it into an electronic signal. But in the natural world, “spiders aren’t sensing pressure.” Miles said “Most animals don’t hear that way, they sense the motion of the air” Future microphones, like those used in hearing aids, could be designed with this in mind.

In the autumn, Buck started to see moose (驼鹿) in the forest. One day he met a group of about twenty. The largest was two meters tall, and his antlers were more than two meters across. When he saw Buck, he got very angry. For hours Buck followed the moose; he wanted the big one, but he wanted him alone. By the evening Buck had driven the big old moose away from the others, and then he began his attack. The animal weighed six hundred and fifty kilos — he was big enough and strong enough to kill Buck in seconds. Patiently, Buck followed him for four days, attacking and then jumping away. He gave him no peace, no time to eat or drink or rest, and slowly the moose became weaker. At the end of the fourth day, Buck pulled the moose down and killed him. He stayed by the dead animal for a day and a half, eating and then turned towards camp and John Thornton.

Five kilometers from the camp, he smelt something strange. Something was wrong. He started to run. After a few hundred meters he found the dead body of Blackie, with an arrow through his side. Then he found another sledge-dog, dying, with an arrow in his neck.

Buck was near the camp now, and could hear voices singing. Then he saw the body of Hans, lying on his face, with ten or fifteen arrows in his back. Buck was suddenly filled with a wild, burning anger. He must take his revenge (报仇).

The Yeehats were dancing around the camp, when they heard a deep and terrible growling. Buck came out of the trees faster than the north wind, and threw himself on the Yeehats like a mad dog. He jumped at the first man, and tore out his throat, killing him at once. He jumped onto a second, then a third man, going each time for the throat. The Yeehats could neither escape nor use their arrows. Buck moved like a storm among them, tearing, biting, destroying, in a madness that he had never known before. Nothing could stop him, and soon the Yeehats were running, wild with fear, back to the forest. Buck followed for some time, and then returned to the camp.

He found Pete, killed in his bed. He followed Thornton’s smell to a deep pool, and found Skeet lying dead by the edge. Thornton’s body was somewhere under the water. All day Buck stayed by the pool or walked restlessly round the camp.