The Chinese paddlefish (白鲟)-one of the world’s largest freshwater fish-has been announced extinct. Scientists say the paddlefish, also called the Chinese swordfish, is believed to have a lineage dating back at least 34 million years. With its long nose and mouth, the paddlefish could grow as long as seven meters.

But a research paper recently published in Science of the Total. Environment reported the paddlefish was now extinct. The researchers include scientists from the Chinese Academy of Fishery Sciences, Britain’s University of Kent and the University of South Bohemia in the Czech Republic.

The paper says the paddlefish was announced extinct for two reasons. It said that the fish was not able to survive because of widespread overfishing and damage to its native environment in the Yangtze River.

Researchers discovered 332 different species of fish in the Yangtze River in 2017 and 2018. But they did not find a single Chinese paddlefish They guessed the fish disappeared between 2005 and 2010. The extinction of the Chinese paddlefish was “a huge loss” to nature.

Pan Wenjing is a forest and ocean expert with Greenpeace East Asia. “The ecology of the Yangtze River is almost in ruins due to human activity in past decades” Pan said. She stressed that China had taken measures to improve the Yangtze’s environment, including a 10-year ban (禁令) on fishing.

After the extinction was reported in the news, some Chinese media and Internet users took a look back at the large creatures. Many people appeared to have not heard of the Chinese paddlefish before it was announced extinct.

“Every time I see the news of another species going extinct, heart starts to ache,” wrote one Weibo user. “Humans should not live alone on this planet,” the user added.

What do you do when you are cold? Your may wrap yourself in a warm blanket and sip a cup of steaming cocoa. All animals have different ways of responding to the cold. Some animals, such as Canada geese, move to warmer climates. Others sleep for the whole winter. But the wood frog does something unusual. It freezes.

The wood frog’s ability to freeze its body is vital to its survival. The wood frog can live in extreme climates from the Appalachian Mountains, across much of Canada, and into Alaska. When temperatures are cold, a wood frog digs down a few inches beneath the leaves on the forest floor. As the outdoor temperature decreases, the frog’s skin freezes. For a human this would result in cold injury, or the freezing of body tissues. But the wood frog has a natural defense against the cold that is remarkable.

Special proteins inside the frog’s body freeze the water in the frog’s blood. Water forced out of the frog’s other cells freezes as well. But a special solution produced inside the frog acts like antifreeze in a car, protecting the cells.

In cold temperatures the frog’s heartbeat, breathing, and brain activity stop. Because the organs are surrounded by ice, they do not rot away (腐烂) and do not require oxygen or nutrients. In fact, about 65% of the frog freezes. The frog, however, is still alive.

The wood frog can freeze for a few days or several months at a time. It can survive temperatures as low as 18°F without damage to its body. When the temperature outside increases, the frog thaws (变暖) along with its surroundings. Water and blood begin circulating in its body again. Within a few hours its heart starts beating again. Over the next several hours, the frog slowly regains use of its legs―and hops away.

Scientists are extremely interested in the wood frog’s ability to freeze. For years they have sought ways to freeze body tissue without damaging it. They hope that in studying wood frogs they may learn better ways of preserving human organs for transplants and other medical procedures. Whether these frogs can be used to help humans or not, they certainly are amazing.

Although similar in appearance to hyenas, African wild dogs are nevertheless true wild canine. They are a mixture of black, yellow, and white in such a wide variety of patterns that no two individuals look exactly alike. African wild dogs are widely distributed across the African plains but they do not live in jungle areas.

They are social animals, living in groups of usually from 2 to 45 individuals. A hierarchy exists within the group, but the animals are friendly to one another. The young and the infirm are given special privileges within the group.

African wild dogs use their sense of sight, not smell, to find their prey. They can run up to 55 km/h for several kilometers. In eastern Africa, they mostly hunt Thomson’s gazelles, but they will also attack calves, warthogs, zebras, impalas, and the young of large antelopes such as the gnu.

Growing human populations have decreased or degraded the African wild dog’s habitat and also diminished their available prey. Road kill and human persecution have also had a negative impact on African wild dog populations. This species is also susceptible to a variety of diseases such as distemper, which is controlled in domestic dogs. Conservation of the African wild dog’s natural habitat must have the highest priority, as these dogs suffer in habitats modified by human intrusion.