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

For lots of animals---humans included---lazing about in the sunshine is one of life's greatest pleasures. But unfortunately, this leisure comes with a cost: sunburn. And, while its most likely victims are the fairer-skinned among us, animals are at risk of sunburn, too. But if this can happen to animals too, why, then, don't we ever see sunburned fish?

"If you think of it, the sun has been here forever in terms of our planet, and all individuals have been exposed to it," said Karina Acevedo-Whitehouse, a molecular epidemiologist from the Autonomous University of Queretaro, in Mexico. So, it's a pretty strong selective pressure that the sun has put on animals and that has led to many mechanisms of reacting to it."

Some of these mechanisms are obvious: hair, fur, wool, feathers and scales（鱼鳞）on many creatures create a barrier between sunshine and skin.

But, "marine mammals（海洋哺乳动物）, and specifically cetaceans（whales, dolphins and porpoises）, are an exception because they don't have fur; they don't have scales," said Acevedo-Whitehouse, who has been studying sunburn in whales for over five years.

In skin samples taken from the backs of blue, sperm and fin whales on their cross-ocean migrations, Acevedo-Whitehouse and her colleagues discovered signs of sunburn from the whales' hours spent breathing and socializing at the surface. But crucially, they also discovered that whales have specialized mechanisms that help them cancel out this burn. "The common adaptation of cetaceans is that they appear to be very effective at repairing damage," she said.

Some whales generate colors that darken and protect their skin; others have genes（基因）that set off a protective stress response in the skin. There are even whales that have developed a hard, keratinized layer（角质层）that protects the delicate skin below. "We were excited to see there isn't really evidence of skin cancer in whales," Acevedo-Whitehouse said. Now, they're trying to understand precisely how those healing mechanisms work.

Every summer, the calls of thousands of swamp sparrows can be heard across North America's wetlands. These little brown birds know only a few songs, but they know them very well. In fact, their musical set list probably hasn't changed much for centuries.

Like humans, baby swamp sparrows learn to communicate by copying adults. From a young age, they learn to copy, or mimic, songs sung by their elders. “Swamp sparrows very rarely make mistakes when they learn their songs,” says biologist Robert Lachlan. In fact, their mimicry is so accurate that the music changes little between generations.

Just like children, the sparrows don't remember every song they hear. Lachlan says. “They don't just learn songs at random; they pick up commoner songs rather than rarer songs.” In other words, they learn songs they hear most often. It's an example of a strategy that scientists call conformist bias. Until recently, this learning ability was thought to be special only to humans.

Between 2008 and 2009, Lachlan's research team recorded the calls of 615 male swamp sparrows across the northeastern United States. The researchers used computer software to break each song into a collection of notes, or syllables. They then measured the differences between the tunes.

The research revealed that only 2 percent of male sparrows sang a different song from the standard tune. The combination of accurate mimicry and conformist bias allows the birds to create traditions that last for centuries. “With those two ingredients together, you end up with traditions that are really stable,” says Lachlan. “The song-types that you hear in the marshes of North America today may well have been there 1,000 years ago.” Lachlan's study is also among the first to measure the longevity of song traditions within a bird species.

The findings are really exciting, says scientist Andrew Farnsworth. He hopes that future research will evolve from these studies. For example, scientists may be able to identify how other animals are able to preserve their cultural traditions. “Seeing the potential for it in other organisms is super cool,” says Farnsworth.