Which animal will last on Earth?

Researchers predict tardigrades will be the last creatures left on Earth when nuclear war or a cosmic event like a nova destroys the planet.

Life has existed on Earth for at least 3.7 billion years. However, in the future Earth may only have a single species left . It's not a cockroach or a scorpion, nor a human, but more likely a tiny water bear , according to IFL Science .

Water bears are famous for being the toughest creatures on Earth. (Photo: Science Photo Library)

A serious threat to the survival of all living things is nuclear weapons . After the war, radioactive fallout will spread across the globe. At the same time, soot from the bomb blast would enter the atmosphere, creating nuclear winter, a period of prolonged darkness and cold. This can cause the foundation of the ecosystem to collapse by preventing photosynthesis, leading to many animals starving to death. Researchers have shown that life in some parts of the planet can survive nuclear war for a while, even though humans no longer exist. Among them are persistent invertebrates such as cockroaches and scorpions as well as microorganisms.

On a larger scale, the threat from astrophysical events such as gamma-ray bursts, large asteroid impacts and supernova explosions has the potential to effectively destroy life on Earth. For example, a supernova explosion would dump large amounts of cosmic radiation on Earth, destroying the ozone layer that blocks harmful ultraviolet rays from the Sun. In 2017, scientists at Oxford and Harvard Universities studied the durability of life in the face of astrophysical events. They concluded that the only animal that could escape extinction from any astrophysical disaster is the tardigrade.

"We were surprised to discover that whether a nearby supernova explosion or a large asteroid impact would cause disaster for humanity, tardigrades may not be affected. So, the huge number of species, or even entire species, may become extinct, but life continues," said Dr. David Sloan, co-author of the 2017 study and research assistant in the Department of Physics at Oxford University. .

Water bears are eight-legged microscopic animals famous for being the toughest creatures on the planet . On the taxonomic tree, they are not bacteria, amoebas, archaea, or fungi. To overcome the harsh environment, this tiny creature enters a deep hibernation state called cryptobiosis , removing more than 95% of water from its body and curling up into a ball. They have can survive temperatures as low as -272.95 degrees Celsius and as high as 150 degrees Celsius, as well as extreme pressures and intense radiation. Water bears can even live in the vacuum of space and can withstand explosions supernova.

However, life on Earth will end with the death of the Sun. The sun will begin to die in about 5 billion years as it runs out of hydrogen. As it progresses to the next stage, the red giant, the Sun will expand, becoming so large that it will swallow the nearest planets Mercury, Venus and then Earth. In the process, the Earth will heat up and be immersed in strong radiation. The ocean will evaporate and the atmosphere will disappear, leaving behind a hot, dry landscape. Even tardigrades wouldn't survive in those conditions.