The humble beaver could hold the key to saving our water, according to a new research that has found how their dam building skills protect the rivers threatened by climate change.

The research, done on rivers in Colorado, found the wooden barriers built by beavers raise water level upstream. As it builds up, the water flows into surrounding soils and secondary waterways. These acts separate out extra nutrients and pollutants before water reenters the main channel downstream.

Extreme weather events, such as severe storms, impact water quality in major river systems. Droughts and floods are becoming more frequent, and the scientists have also found they are contributing to an increase in the American be aver in the US, and consequently an explosion of dam building.

The team chose to monitor a 40-kilometer stretch of the East River. They reviewed data on water levels gathered hourly by sensors fixed in the river and the areas along the river.

They also collected water samples, including from below the ground’s surface to monitor nutrient and pollutant levels. The researchers compared water quality along the stretch during a historically dry year, to water quality the following year when water levels were unusually high. They also compared these year-long datasets to water quality during the nearly three- month period, starting in late July 2018, when the be aver dam blocked the river.

The study revealed the dams increased nitrate (硝酸盐) by nearly 50% by increasing the pressure of the water flow upstream 10 times over, which pushed more water out into the surrounding areas. This decrease in nitrates, which are absorbed and digested by tiny organisms in the soil, helped increase the oxygen content and quality in the rivers.

Beavers’ handiwork is responsible for the land they love.

Jellyfish are unusual creatures. They’re neither fish nor jelly. Some are among the most colourful creatures in the world, but it’s best to look but not touch these invertebrates（无脊椎动物）. Not only are they very fragile creatures, but many give a painful sting, and some are even deadly. Whether you admire them in an aquarium or try to avoid them in the wild, you won’t be able to get these fascinating jellyfish facts out of your head.

Here’s a jellyfish fact that might come in handy: There are several names for a group of jellyfish. They include smack, bloom, and swarm. Choose the word you prefer depending on whether you think the jellyfish pack looks like a garden of blooming flowers or more like a frightening pack of stingers, and whether you’re admiring them at an aquarium or if you and your fellow snorkelers are surrounded.

Jellyfish have two main forms in their life cycle that look quite different from each other. Scientific American explains that an adult jellyfish, called a medusa, has a bell-shaped body with tentacles（触须）flowing down below it. Young jellyfish, called polyps, look more like sea anemones, with shorter tentacles that flow up above the main body. Medusas reproduce by releasing eggs.

Melanie Roberts, Senior Aquarist at SeaWorld Orlando, says that the largest jellyfish in the world is a lion’s mane jellyfish. The body of this beautiful orange jelly can grow up to three feet in diameter. With its 12,000 tentacles that can grow 120 feet long, Oceana.org adds that the lion’s mane jelly compares in size to the planet’s largest animal: the blue whale.

Regardless of their size, jellyfish are mostly made of water. In fact, they’re about 95 per cent water.These creatures don’t have brains, blood, or bones. And most jellyfish don’t have eyes. Jellyfish also use their mouths both for eating and for waste removal.

Pets should not be left alone for too long during the day. But our busy lifestyles will sometimes tear us away. 【小题1】 Here are some tips to keep your pets content.

Cats don’t simply curl up and sleep when you leave. 【小题2】 If they have a friend or sibling they will create games and comfort one another but if they are alone they will need more stimuli (刺激物). Leaving the TV or radio on can help, and while you work out their favorite channel, you can’t go far wrong with classical music.

【小题3】 They will keep your cat physically and mentally busy, which will lessen the separation anxiety. Some of the toys are also practical for your home, such as scratching posts to prevent the furniture from being scratched.

It’s not just cats that suffer from separation anxiety. Dogs also dislike being left alone and unfortunately they can’t tell whether it’s been ten minutes or ten hours: the displeasure felt is very similar.

【小题4】 Background noise from the TV or radio can help them to feel less alone. There is even a dog TV channel designed to create happy and calm thoughts in dogs, showing idyllic scenes of fields, beaches and other dogs.

You can also gradually lengthen the distance and time of your separation until your dogs can be left alone for 20 minutes without showing their usual symptoms of sadness and stress. 【小题5】