Do you know why different animals or pests (昆虫) have their special colors? Colors in them seem to be used mainly to protect themselves.

Some birds like eating locusts (蝗虫), but birds cannot easily catch them. Why? It is because locusts change their colors together with the change of the colors of crops. When crops are green, locusts look green. But as the harvest time comes, locusts change to the same brown color as crops have. Some other pests with different colors from plants are easily found and eaten by others. So they have to hide themselves for lives and appear only at night.

If you study the animal life, you’ll find the main use of coloring is to protect them. Bears, lions and other animals move quietly through forests. They cannot be easily seen by hunters. This is because they have the colors much like the trees.

Have you ever noticed an even stranger act? A kind of fish in the sea can send out a kind of very black liquid (液体)when it faces danger. While the liquid spreads over (散开), its enemies cannot find it. And it immediately swims away. So it has lived up to now though it is not strong at all.

The local dog park might be getting busier and cat cafés might be opening in every neighborhood, but do you know which traditional pet is the most popular around the world?

The United States is home to the highest number of domestic (驯养的) dogs, cats, and fish, and Americans are more likely to treat their friends like humans. U.S. pet owners spend $50 billion a year on their animal companions, and 36% of dog owners have used some of that money to buy their pet a birthday present.

According to Russian tradition, keeping a cat as a pet is good fortunate, so it's no surprise the cat is Russia's most popular pet. In 2016, 57% of Russian households contained a cat, compared to the 29% that had dogs. On March 1, Russia celebrates National Cat Day as part of celebrations for World Cat Day.

Brazils domestic bird population was about 19 million in 2013, while dogs held top rank at just over 37 million. Brazil has the highest number of small dogs per capital city in the world. The nearly 20 million small dogs are attributed to (归因于) a rapidly-growing middle class living in small urban apartments.

Dogs and cats rank second and third in Britain, while fishes hold the top spot. It has been linked not only to the low maintenance (维护), but also to the fact that many other pets like dogs or cats are not allowed in some places.

The U.S.has more than 4,000 wild bee species,and many are in danger of dying out due to human activity,chemical overuse and climate change.In Colorado,the Girl Scout troops(童子军团)have take on the task of saving bees.They made tiny homes for wild bees called"bee hotels" to fight the big drop in the population of bees.

Bee hotels are like birdhouses for wild bees.Since wild bees don't make honey,they don't live in the containers for bees,but they always need a suitable habitat(栖息地）.Out in the wild, these bees often live holes of dead trees and broken branches.But natural habitats can be hard to come by in the developed areas,which are where bee hotels come in.Dennis vanEngelsdrop,a professor at the University of Maryland,says that bee hotels play an important role in keeping the wild bee population.When wild bees check out of their hotel rooms,they leave their kids behind. A wild bee produces her eggs and leaves food for them to eat.If built correctly,bee hotels can even attract new bee species.

The troops repurposed carboard boxes,paper pipes,etc.to create homes for bees in their local community.A hotel design can be as simple as paper pipes stuck into a box.After building their bee hotels,the girls went out to place them in green pockets of their community,such as community gardens."The most interesting thing I learned is when you think of bees,you just think of honeybees,but there are so many different types,"says Aimee,a Girl Scout.Working with bees can be a daunting task.Many children only know them from the pain of bites.But the Girl Scouts learned to overcome their fears."It was hard for me to go to look at the bees,"says another girl."I'm glad I' did.We need bees for food and flowers.”

Bees are a big deal in the world of plant reproduction.They move pollen(花粉）from one plant to another.While honeybees live communally,most bee species are wild and live on their own.Honeybees may be better known,but wild bees are important pollinators(授花粉者）too.

The bee hotel project also plays an important role in bringing up a new generation of responsible citizens."What you're seeing is that you need bees to survive;so who is better to be concerned about that than the young generation?"vanEngelsdrop says."These efforts are really good because hopefully the girls will show lifelong devotion to the preservation."