Chinstrap penguins (帽带企鹅) in Antarctica have adapted to hard conditions by sleeping in a very unusual way.

Like other penguins,chinstrap penguins spend much of their time in the water,catching fish to eat. But when the time comes to raise their young, they return to land. Raising young penguins is a challenge. The eggs are often laid in “homes” made of small rocks to keep the eggs from the cold. One parent takes care of the home for long periods of time, while the other parent hunts for food. The parent must often keep a sharp lookout. Birds called brown skuas attack the eggs and young penguins of careless parents. Other penguins in these crowded areas may take stones from the home, putting the young in danger. But it’s hard to stay vigilant and protect a home 24 hours a day. Getting a good night’s sleep could be deadly for the young. How do chinstrap penguins solve the problem?

So a group of scientists began to study them. They recorded the birds on video.Eleven days of studying the penguins discovered that the tired parents were actually sleeping. They take thousands of tiny naps (小睡) each day. Each nap lasts only about 4seconds. By taking over 10,000 naps a day,the scientists say the penguins get a daily total of about 11 hours of sleep. They do it 24/7 for several weeks at a time. They can keep going and raise their young.

It’s not clear if the naps allow the penguins to actually feel rested, or if it’s just enough to allow them to keep going. The scientists don’t know yet if the penguins sleep this way at other times of the year, or only when they’re raising their young. They also don’t know if other kinds of penguins have similar sleeping habits.

Camouflage(伪装) is a type of coloration or pattern that helps an animal blend in with its surroundings. Camouflage is often used by prey as a way to disguise themselves from predators. It is also used by predators to conceal themselves as they follow their prey.

Concealing coloration allows an animal to blend into its environment hiding it from predators. Some animals have fixed camouflage, such as polar bears, whose white coloration helps them blend in with the Arctic snow. Other animals can change their camouflage at will based on where they are. For example, some marine creatures can alter their coloration to blend in with surrounding sand and rock formations. Some other animals have a type of seasonal camouflage. This includes the snowshoe hare, whose fur turns white in winter but brown during summer.

Disruptive coloration includes spots, stripes, and other patterns that breakup the outline of an animal’s shape and sometimes conceal particular body parts. The stripes of a zebra’s coat, for example, create a disruptive pattern to flies, whose compound eyes have trouble processing the pattern. Some animals have a particular type of camouflage called a disruptive eye mask. This is a band of color found on the bodies of birds, fish, and other creatures whose eye is usually easy to spot because of its distinctive shape. The mask makes the eye nearly invisible to avoid being seen by predators.

Disguise is a type of camouflage where an animal takes on the appearance of something else in its environment. Some insects, for example, disguise themselves as leaves by changing their shading. Other creatures also disguise themselves, like the walking stick or stick-bug, which resembles a slim branch.

Mimicry is away for animals to make themselves look like related animals that are more dangerous or otherwise less appealing to predators. This type of camouflage is seen in snakes, butterflies, and moths. For example, the scarlet kingsnake, a type of harmless snake found in the eastern United States, has evolved to look like the coral snake, which is highly poisonous. In this case, the animals’ deceptive coloration helps ward off other creatures that might be looking for a meal.

In Shark Bay, Australia, dolphins that aren't related have been observed teaching each other a new way to use a tool, a behavior that until now scientists have found only in humans and other great apes. It's also the first known example of dolphins transmitting such knowledge within the same generation, rather than between generations.

In a practice called shelling (脱壳) , dolphins will chase fish into discarded giant snail shells on the seafloor, then bring the shells to the surface and shake them with their noses , letting out the water and catching the fish that fall out. “The fact that shelling is socially transmitted among dolphin peers rather than between mother and children sets an important milestone.”. senior study. author Michael Krützen, said in a press statement.

“Though dolphins and great apes have very different evolutionary histories and habitats, they're both long-lived, large-brained mammals with tremendous (巨大的) capacity for innovation and culture,” Krützen says. Maggie Stanton, a psychologist at Franklin & Marshall College in Pennsylvania, who has studied Shark Bay dolphins and chimpanzees at Tanzania's Gombe Stream National Park, agrees. “One chimp (黑猩猩) family in Gombe,” she notes, “may have learned how to use tools to catch ants from a female chimp that joined the community.

In 2007, Krützen launched a study of Shark Bay's dolphins. Scientists observed shelling 42 times among 19 dolphins. Half of these events occurred after a marine heatwave in 2011, which may have caused a die-off among giant sea snails , leading to more discarded shells on the seafloor. “Although 42 observations is a small data set,” the scientists add, “it's likely the behavior is actually common; it only lasts a few seconds , making it harder for people to spot from a boat.”