認識緩步動物：挑戰空間、熱量和時間的微型超級倖存者！

Tardigrades, also known as water bears or moss piglets, are some of the most resilient creatures on Earth. These tiny animals, measuring only about 1 millimeter long, have amazed scientists with their ability to survive in extreme environments. Whether they are baked, frozen, shot from a gun, or sent into outer space, tardigrades often come out alive. Some experts even believe that tardigrades could outlive humans and survive until the Sun dies.

Under a microscope, tardigrades look quite unusual. They have eight legs with sharp claws and faces that seem almost monstrous. Despite their odd appearance, their survival skills are what truly set them apart. Tardigrades have been found in places with lots of moss and leaves, but they also live in harsh environments like mountaintops, deep oceans, and even acidic hot springs. In 2007, tardigrades became the first known animals to survive being sent into space without protection. Some of them even laid eggs while in space, and the young hatched healthy.

Scientists have put tardigrades through many tests to see how tough they really are. They can survive being heated to 150 degrees Celsius and frozen to temperatures close to absolute zero. In one experiment, tardigrades were fired from a gun at speeds faster than a bullet, and many survived. Their secret lies in their ability to enter a 'tun state,' where they dry out, shrink, and slow their metabolism to almost nothing. In this state, they can survive for decades and come back to life when water is available.

Researchers have discovered special proteins in tardigrades called TDPs (tardigrade-specific intrinsically disordered proteins). These proteins help protect their cells when they dry out by forming a gel-like cushion inside the cell. This keeps the cell's contents safe and prevents damage. Other animals use sugars like trehalose for protection, but tardigrades rely on these unique proteins.

Tardigrades can also survive extreme heat, but only when they are in their tun state. If they are in water and exposed to high temperatures, they die like other animals. This shows that their survival tricks only work in certain situations. Tardigrades are also vulnerable to climate change, as they may not always have time to enter their tun state before temperatures rise.

Freezing is another challenge that tardigrades can handle. Some have survived being frozen for 30 years in Antarctica. Freezing usually damages cells by forming ice crystals, but tardigrades can avoid this by slowing down their metabolism and entering a suspended animation.

Radiation is deadly for most living things, but tardigrades have proteins like Dsup that wrap around their DNA and protect it from damage. Scientists have even put Dsup into human cells, making them more resistant to radiation. This discovery could help protect people from radiation during cancer treatment.

Tardigrades' superpowers have inspired scientists to find ways to use them for human benefit. For example, their proteins could help preserve medicines and vaccines without refrigeration, which is important for people in remote areas. NASA is interested in using tardigrade tricks to protect food and medicine during long space missions.

The reason tardigrades have evolved these abilities is still a mystery. Because they are so small, they can be blown by the wind to new places, where they might face extreme conditions. Their survival skills may have developed to help them cope with these challenges. By studying tardigrades, scientists hope to unlock new ways to protect both humans and these incredible creatures from the dangers of our changing world.