We all know that zebras have stripes (条纹). However, both animal experts and zebra fans all over the world haven’t known the reason for centuries. But now it appears that some researchers in California may have finally solved the age-old mystery!

In order to find the reason why zebras have stripes, a team of scientists led by Professor Tim Caro set to work. They began by comparing the thickness, location, and the stripes on seven species of zebras that live in various geographic locations. They then examined some factors that may continuously affect zebras, such as their natural enemies, the temperatures of their living places and the small insects around them like flies. To their amazement, the only factor that was linked with the stripes was the annoying flies. The zebras with the most obvious and the largest number of stripes mostly live in areas with more flies.

But that led to another question: why are zebras the only kind of animal smart enough to develop the stripes? After all, there are plenty of other animals like horses and donkeys, which are facing the same trouble. Upon closer examination of the black and white animals, the researchers noticed that unlike the others, zebras have very short coats of hair, making them particularly easy to be bitten (咬) by the flies!

While Tim says that this mystery is finally solved, it has given rise to a new one. Why are these fearless flies that have no fears of attacking animals that are thousands of times bigger, afraid of black and white stripes? If you have any answer, be sure to add it to the comments below. It may help the professor with his new research!

Otters（水獭）are cute water animals. These days, keeping otters as pets is getting popular. In Japan, some “Otter Cafes（咖啡馆）” are open for business. People can pay to play with the otters there and to take photos with them. In Indonesia, people go swimming with their pet otters and take funny videos. These photos and videos posted online have interested more people to buy otters as pets.

However, these enjoyable photos and videos hide the damage that the online trade is doing to otters. In fact, wild otters are facing many threats — they have long been hunted for their coats; in some places, fishermen have been killing otters in order to stop them from eating fish; and now, the online pet trade has become another big problem for otters.

In the wild, baby otters usually stay with their mothers during their first year of life. According to a report, 70% of the otters sold online are under one year old. These baby otters have been stolen from their mothers. When they are kept as pets by humans, they do not live full and natural lives.

Otters are very social. They live in family groups of up to 15 in the wild. Keeping an otter as a pet can make it very sad and lonely.

These animals also need enough space to swim. Their owners’   bathtubs（浴缸）or pools are nowhere near as large as the bodies of water in the wild.

On the other hand, it’s not proper to keep otters as pets at home. They have a very special fishy smell. If they are kept indoors, they will leave a lot of waste around the house. This would make the smell even more unpleasant. Besides, when otters are unhappy, they will make loud noises and even attack（攻击）people. If a person is hurt by an otter, he or she needs to go to hospital at once.

So we should stop the otter pet trade and never share photos and videos about them online.

Mona is an Australian koala. She is seven years old. She is very cute. She likes sleeping during the day. 【小题1】 Mona doesn’t drink water for months, but she is healthy. 【小题2】

Here is a big house. A lion lives in it. Her name is Lily. She is from South Africa. Meat is her favorite food. Lily is very lazy. 【小题3】 Today is Lily’s eighth birthday. The workers in the zoo are having a birthday party for her.

This is a big elephant. His name is Johnny. He is from India. He’s eleven years old. He has bad eyesight (视力). He likes to eat grass. He’s friendly and smart. 【小题4】

Tuantuan is a cute panda. She is five years old. She’s from China. She is very beautiful but she’s very shy. 【小题5】 She likes eating bamboo and drinking water. She relaxes about 10 hours a day.