Lions are opportunists. They prefer to eat without having to do too much work. When resting in the shade, they are also watching the sky to see what is flying by, and even in the heat of the day they will suddenly start up and run a mile across the plains to find out what is going on. If another animal has made a kill, they will drive it off and take the dill for themselves. A grown lion can easily eat 60 pounds of meat at a single feeding. Often they eat until it seems painful for them to lie down.

The lionesses (母狮) , being thinner and faster, are better hunters (猎手) than the males (雄狮). But the males don’t mind. After the kill they move in and take the test share.

Most kills are made at night or just before daybreak. We have seen many, many daylight attempts but only ten kills. Roughly, it’s about twenty daytime attempts for one kill.

When lions are hiding for an attack by a water hole, they wait patiently and can charge at any second. The kill is the exciting moment in the day-to-day life of the lion, since these great animals spend most of their time, about 20 hours a day, sleeping and resting.

Lions are social cats, and when they are having a rest, they love to touch each other. After drinking at a water hole, a lioness rests her head on another’s back. When walking, young lions often touch faces with older ones, an act of close ties among members of the group.

A．are cruel animals

B．are clever animals

C．like to take advantage of other animals

D．like to take every chance to eat

Finding fish is going to get harder as climate change continues to heat the world's oceans. A new study finds that warming seas over the past 80 years have reduced the sustainable catch of 124 species of fish and shellfish. Sustainable catch refers to the amount that can be harvested without doing long-term damage to the health of populations of some species.

Overfishing has made that decline worse, researchers say. Overfishing refers to catching so many fish that the size of the population falls. In some parts of the world, such as the heavily fished Sea of Japan, the decrease is as high as 35 percent. That's a loss of more than one in every three fish.

Researchers examined changes in 235 populations of fish and shellfish between 1930 and 2010. Those fish populations spread far apart across 38 ocean regions. Temperature changes vary from one ocean site to another. But on average over that time, Earth's sea-surface temperatures have risen by about half a degree Celsius.

On average, that warming has caused the sustainable catch to drop by 4.1 percent, the study found. About 8 percent of the fish and shellfish populations the team studied saw losses as a result of the ocean warming. However, about 4 percent of some populations increased. That's because certain species have thrived in warmer waters. One example is a kind of black sea fish. It lives along the northeastern U.S. coast. As warming continues, these fish will reproduce faster until they reach their limit.

About 3.2 billion people worldwide rely on seafood as a source of food. That means it's urgent for commercial fishing fleets and regulators to consider how climate change is affecting the health of all of those fish in the sea.

Most animal species use sounds to communicate.But for spiders，sound is not a big part of their lives.In fact，they have no ears or other specialized sound­sensing organs.So it came as a big surprise to Alexander Sweger when he discovered one species of wolf spider communicates using sound.

Sweger is a scientist who studies various kinds of wolf spiders.Among these wolf spiders is one species that for almost a century has been known as the purring(会发出咕噜声的) spider.Scientists suspected this particular type of wolf spider might be using that purring sound to signal its interest in finding a mate.But no one had ever confirmed this.So Sweger decided to investigate.

“At mating time，male wolf spiders try to catch a female’s attention by creating “persuasive” vibrations(振动)，”says Sweger.They rub one structure of their body against another—somewhat as a cricket(蟋蟀) does—to impress the female.“Purring spiders use the same strategy as every other wolf spider in North America does，and they use the same structures，”says Sweger.But the scientist showed that compared to the courtship(求爱) vibrations made by other wolf spiders，those made by Gladicosa gulosa are far stronger.

Sweger discovered something else as well.When a purring spider was on a surface that is good at transmitting vibrations，such as leaves，an audible(听得见的) sound was produced.If a person is within a meter of the courting spiders，he or she can actually hear the sound.The courtship vibrations made by purring spiders—at least when leaves or paper are involved—create an audible sound so loud that it can broadcast a guy’s message to a distant female.But she apparently only “hears” it if she’s also standing on something that can make a sound，such as a leaf.

Sweger’s learned this in his lab.His team let a male purring spider make those courtship “calls”．The scientists then played a sound recording of the guy’s purr through the air.Males in another cage ignored these calls.So did female spiders standing on something hard.But if the female was atop a surface that could vibrate，like a piece of paper，then she began moving around.It signaled she had picked up the guy’s message.And it suggested she had to “hear” the audible call as a leaf’s vibrations under her feet before she got the message that a potential mate was out there.