How many species extinctions have the planet experienced? What are the reasons?

The earth has experienced five species extinctions, the first was the Ordovician Silurian extinction event, during which a large number of marine species were extinct, many organisms were reduced, and the reason for this extinction may be due to the rapid decline in sea temperature caused by continental glacial activity, which led to the inability of many organisms to adapt to the environment at that time, resulting in extinction. The second extinction was the late Devonian extinction event, which can be said to be the extinction of all animals on land and sea, in addition, the once flourishing organisms were not spared in this disaster, and the main reason for this extinction was also the development of glaciers that led to the decline of global temperature during the Ice Age, that is, all organisms were unable to adapt to the temperature at that time and caused death and extinction.

The third extinction occurred in the Permian, the Triassic period, this extinction can be said to be the largest extinction, because all life was lost at that time, this extinction can be said to be a lot of insects, and even mammals have produced a certain extinction Dinosaurs also caused extinction in that period, and the reason for this extinction may be because the destruction of ozone has harmed the world's organisms, thus causing the extinction of species, Another reason is that volcanic eruptions have polluted the environment, and forest fires have become frequent, causing all living things to become extinct.

The fourth is the Triassic Jurassic extinction event, during this period organisms began to undergo serious differentiation, so all the non-animals were extinct, and vertebrates were also extinct, and all the animals in the ocean were able to stay and very few, this extinction may be caused by volcanic eruptions caused by plate shifts, releasing carbon dioxide, causing extreme weather conditions, causing a large number of extinctions and deaths of organisms around the world. The fifth extinction was the extinction event at the end of the Cretaceous period, during this period, whether it was the animals and birds in the sea, or even the dinosaurs, there were some extinctions, and even no animals could be spared, and the main reason for this is that the vegetation has decreased due to the decline in sea level, so that the dinosaurs have no food, and the other is the eruption of volcanoes, which has changed the environment and caused a large number of biological deaths.

There have been 5 extinctions on Earth; The main thing is that the environment has changed, the weather is getting warmer, we are destroying the environment, and there are fewer and fewer rare species.

It seems that it is extinction five times, and the reason is that the environment has changed drastically, the area of sunlight radiation has decreased, and the temperature has decreased.

There have been five widely recognized mass extinction events in Earth's history, and they are known as the "Great Five Extinctions" or "Five Mass Extinctions". These mass extinction events have led to massive species extinctions and dramatic reductions in biodiversity. The following is a brief introduction to the five major extinction premature ascension events:

Ordovician Silurian mass extinction (about 100 million years ago): This is the earliest mass extinction event to date, occurring from the late Ordovician to the early Silurian period. It is estimated that about 86% of marine species and 70% of terrestrial species are extinct, with the main reasons likely to be climate change and sea level decline.

End Permian mass extinction (about 100 million years ago): This was the worst mass extinction event, with an estimated extinction of about 96% of marine species and 70% of terrestrial species. Possible causes include volcanic eruptions, climate change, and methane releases.

End Triassic Mass Extinction (about 100 million years ago): This mass extinction event caused the extinction of about 70% of all species, including most marine and terrestrial organisms. Possible causes include volcanic eruptions, climate change, and sea level changes.

Extinction at the end of the Cretaceous period (about 66 million years ago): This is the most famous mass extinction event that led to the extinction of dinosaurs and many other biomes. The probable cause is that a meteorite with a diameter of about 10 kilometers hit the Earth, triggering widespread volcanic eruptions and climate change.

Cambrian Devonian mass extinction (about 44 million years ago): This mass extinction event had a low impact, with about 50% of marine species extinct The main reasons are likely to be climate change and a lack of oxygen in the oceans.

These mass extinction events have had a long-term impact on the planet's biodiversity and have had a significant impact on evolution and the evolution of ecosystems. Bu Lao.

Every hour, a species is forever extinct from the earth, and it is hard to imagine that a species that survives thousands of years of natural selection evolution ends its strong evolutionary history in an hour. This is just a microcosm of the path of wildlife being driven to extinction by humans. The history of the development of human society can be said to be the history of the continuous development of human beings using wild animal and plant resources.

However, in the nearly 200 years since the Industrial Revolution, with the expansion of population and rapid economic development, the variety and abundance of wild animals and plants have decreased at an alarming rate. According to scientists' estimates, due to the strong disturbance of human activities, the rate of loss of species in modern times is 1,000 times faster than the rate of natural extinction and 1 million times faster than the rate of formation, and the rate of species loss has accelerated from about one species per day to one species per hour. According to the world's Red Book, 110 species and subspecies of mammals and 139 species and subspecies of birds disappeared from the earth in the 20th century.

Since the 16th century, about 150 species of birds, 95 species of mammals, and about 80 species of amphibians and reptiles have become extinct on the earth. At present, 593 species of birds, more than 400 species of mammals, 209 species of amphibians and reptiles, and more than 20,000 species of higher plants are endangered in the world. In addition to the irresistible natural history and natural disasters, human activities are the main causes, especially the predatory use of wild animal and plant resources by human beings due to commerce, which is an important factor causing species endangerment and even extinction.

At present, the scale of illegal wildlife smuggling in the world has reached an alarming level, becoming the third largest illegal after arms and drug smuggling. 1 trained Saker is worth $5,000 to $20,000; 1 parrot is worth about $4,000 to $40,000; 1 kilogram of musk is worth $50,000; 1 Tibetan antelope scarf worth $35,000; 1 orchid** can also be as high as $2,000; A candelabra cactus can reach $7,000. The monetary size of all this amounts to at least more than $6 billion.

Seeing such a series of figures, it is not difficult to understand why wildlife is legal and illegal** and why it is so popular.

Earth's first mass extinction occurred at the end of the Ordovician period, 100 million years ago, when about 85% of species went extinct.

In the late Devonian period, about 100 million years ago, the second mass extinction occurred, and marine life was devastated.

The third mass extinction, which occurred at the end of the Permian period about 100 million years ago, was the largest and most serious in the history of the earth, estimating that 96% of the species on the planet were extinct, including 90% of marine life and 70% of terrestrial vertebrates.

The fourth occurred 100 million years ago, when 80 reptiles became extinct.

The fifth occurred 65 million years ago, in the Cretaceous period, and it is also known to everyone, when the dinosaurs that ruled the earth for hundreds of millions of years went extinct.

The sixth mass extinction is now underway, and humans are to blame.