The Ordovician-Silurian extinction (440 to 450 million years ago) was the first “great extinction” that occurred about 450 million years ago. It is considered the second largest extinction in history if measured by the number of species destroyed with 85% of fish species and 60% of biological species destroyed. The most accepted cause of extinction is a gamma-ray burst of a near-Earth star that caused a sharp drop in atmospheric carbon dioxide. This created an ice age that lasted 0.5 – 1.5 million years. Lower sea levels combined with the cold of glacial ice brought about a mass extinction in the Ordovician period. Late Devonian Extinction: Over 365 million years ago, one of the five largest and most feared mass extinctions in Earth’s biological history. It happened about 360 million years ago, killing 70% of all living things. Archaeological evidence indicates that this mass extinction could last up to 20 million years. Although it is one of the scariest mass extinctions in the world, its cause is still an unsolved mystery. Permian-Triassic extinction: about 253 million years ago is likened to the bloodiest massacre in Earth’s history. This terrible extinction event wiped out 95% of all species on earth. The main reason is due to the extremely strong tectonic movement of the Earth’s crust. Magma eruptions from fault plates engulfed the entire Earth’s surface in a sea of ​​fire. The increase in dust and carbon dioxide causes the greenhouse effect to warm the Earth. Changes in ocean currents cause great impacts on the ecosystem, ocean circulation becomes stagnant, lack of oxygen. Life now becomes extremely fragile. Triassic-Jurassic Extinction: About 201 million years ago was an extinction that took place about 199.6 million years ago that completely wiped out half of all living things on Earth. It is still not certain what caused the disaster. Scientists predict that a large volcanic eruption has occurred. However, studies have shown quite accurately the time when the extinction took place and the meteor impact that created Lake Manicouagan (Canada). This evidence proves that it is possible that the collision was the direct cause of this extinction. The Cretaceous – Paleogene extinction occurred about 66.5 million years ago, marking the end of the Mesozoic and the beginning of the Cenozoic with the Paleogene period. About 75% of species went extinct after this terrible event. Scientists theorize that this extinction event was caused by one or more simultaneous disasters, such as the powerful impact of meteorites (creating the Chicxulub craters in Mexico, Boltysh in Ukraine). or due to a drop in sea level, powerful volcanic eruptions creating the phenomenon of “Deccan traps” that seriously destroy the Earth’s biosphere. Currently, humans are in the early stages of the latest mass extinction, which is happening much faster than any other species. Since 1970, vertebrate populations have decreased by an average of 68% and now more than 35,000 species are considered endangered. In the 20th century alone, as many as 543 species of terrestrial vertebrates became extinct. Since the beginning of the industrial revolution in 1760, humans have been a major factor in Earth’s current environmental crisis. From greenhouse gas emissions and ozone depletion to deforestation, plastic waste and the illegal animal trade, humans have been proactively depriving the world of some species and threatening many others. Please watch the video: Strange and Unique Natural Phenomena in the World. Source: Strange story VN&TG

Van Xuong fish. You probably never thought that an animal could live without a head, heart and bones. In fact, this species existed 500 million years ago and exists until today, in addition, they are also considered “cousins” of the ancestors of many vertebrates today. The family of vertebrates is extremely prosperous today, with more than 60,000 members, all of whom have different looks, habits and temperaments, but this “cousin” only has one child left. the only living species, they are named Amphioxus – Van Xuong fish, this species is also considered a living fossil. Although Van Xuong fish is called a fish and at first glance, it is very similar to a fish, but it is not actually a fish. On our planet today, most of the animals that exist are vertebrates, such as horses, cattle, sheep, chickens, ducks, dogs, cats, tigers, turtles.. Of course, there are us humans as well. What makes this particular “fish” so strange and unlike any other is that they are cephalopods, without a backbone, but still grouped with vertebrates, Chordates live and form the phylum Chordate. Biologists think that Van Xuong fish are animals in the transitional evolutionary stage from invertebrates to vertebrates, today they are considered to be ancestors of fish, but they are completely different. not fish. The skin of Van Xuong fish consists of two main layers: the epidermis (epidermis) on the outside and the dermis (dermis) on the inside. Unlike most vertebrates, their epidermis has only one layer of cells, while the dermis is underdeveloped, mainly composed of glue or elastic connective tissue. There are more than 66,000 animals in the order Phylum Chordata. The most special thing is that vertebrates account for the largest proportion, with more than 66,000 species, the main subphylum is the sea squid, and there are currently about 3,000 known species; and cephalopods, there are only two families of Van Xuong and Asymmetron fish – there are 30 species. In fact, the skeleton of this fish is the rope that runs along the body and back from the tail to the head. In the gill slit region, the skeleton is a network of many horizontal and vertical connecting rods. The fins and tentacles are also supported by the connecting rod. Their central nervous system is a neural tube running along the body, located above the spinal cord but not reaching the end of the spinal cord, wrapped in a protective glue membrane. Although Van Xuong fish looks like a fish, the biggest difference between it and vertebrates is that it does not have a real head, sense organs such as smell, sight and hearing, even a skull or a skull. teeth are also something too fictitious for them. This animal only has a tuft of elastic “legs” on the head that acts as support for the body. The most amazing thing is that it doesn’t even have a heart, instead it relies on the beating of a portion of blood vessels to transport blood. Their musculature is less differentiated and typically segmented. Therefore, the muscles can only guarantee simple bending movements, suitable for the lifestyle buried in the sand. The muscular system consists of many muscle segments (myomera), arranged from the anterior end to the posterior end of the body. The muscle segments are separated by septa of connective tissue (myosepta). The muscle segments on both sides of the body are arranged alternately with comb teeth. As a result, when swimming, the body bends in the horizontal plane. Amphioxus is widely distributed in the shallow waters of the ocean, Qingdao and Xiamen in China are their main habitats. In addition, there are the coasts of Southeast Asia and the coasts of California and Florida, Norway, the Mediterranean and Africa. Due to its rich nutrition and delicious taste, Van Xuong fish is considered a traditional delicacy in Southeast Asia. Van Xuong fish is 3 to 5cm long, very strange shape. The long, flattened body looks almost like a pole. The whole body is pinkish-pink, semi-transparent, the muscle fibers are clearly visible. They have no scales, no fins, no spine, their internal organs are just a rhythmically pulsating complex tube. There are no senses like eyes, nose, ears. There is no decomposition for the gastrointestinal tract. Apart from the mouth and pharynx, the only remaining part of the intestine is the intestine leading to the anus. Van Xuong fish often follow the tide to swim into the estuary where the seabed is shallow, almost defenseless but capable of penetrating the ground. Their lifespan is about 3-4 years, they often bury half of themselves in the sand, while the other half is exposed to receive plankton from the river. Their musculature is less differentiated, so they can only move in the water by simple bending movements. When not moving, they often bury themselves in the sand. The respiration of Van Xuong fish is also similar to other fishes. They vibrate the cilia (the tentacles in the mouth) to bring water from them to the gill slit. The wall of the gill slit has many blood vessels, where gas exchange occurs.

You probably never thought that an animal could live without a head, heart, or bones. In fact, this species existed 500 million years ago and exists to this day, in addition they are considered “cousins” of the ancestors of many species of vertebrates today. The vertebrate family of today is extremely prosperous, with more than 60,000 members, all of them with different looks, habits and temperament, but this “cousin” has only one child. Only alive, they are called Amphioxus – Van Xuong fish, this species is also considered living fossils. Although Van Xuong fish is called fish and at first glance it is very similar to fish, it is not actually fish. On our planet today, most animals that exist are vertebrates, such as horses, cattle, sheep, chickens, dogs, cats, tigers, ba … Of course, there are us as well. What makes this particular “fish” so exotic and unlike any fish is that they are vertebrates, have no vertebrates but are still grouped with vertebrates, cord animals and form the Chordate branch. Biologists believe that Van Xuong fish are animals during the transition from invertebrates to vertebrates, today they are considered to be the ancestors of fish, but they are completely not fish. The skin layer of Van Xuong fish has 2 main layers, the outer epidermis and the dermis on the inside. Unlike most vertebrates, their epidermis has only 1 cell layer, while the epidermis is underdeveloped, mainly composed of colloid or elastic connective tissue. There are more than 66,000 species of animals in the order Phylum Chordata. The most remarkable thing is that vertebrates make up the largest proportion, with more than 66,000 species, the main caudal subsector is the sea level, and there are currently about 3,000 known species; and head vertebrates, only two families of fish Van Xuong and fish Asymmetron – there are 30 species. In fact, the skeleton of this fish is the wire that runs along the body and back from the tail to the head. The gill region, the skeleton, is a network of horizontal and vertical interconnected rods. The fins and tentacles are also supported by the connecting rod. Their central nervous system is a neural tube running along the body, located above the spinal cord but not reaching the end of the spinal cord, wrapped in a protective glue film. Although the Van Xuong looks like a fish, the biggest difference between it and its vertebrates is that it does not have a real head, sensory organs such as smell, sight and hearing, even a skull. The teeth are also something too fictional for them. This animal has only a bunch of elastic “legs” on the head to play the role of supporting the body. The most amazing thing is that it doesn’t even have a heart; instead, it relies on the beat of part of the blood vessel to carry blood. Their musculoskeletal system is less dissociated and typical dissociated. Therefore, muscles can only ensure simple bending movements, consistent with the lifestyle of being buried in the sand. The muscular system consists of many muscles (myomera), arranged from the front end to the posterior end of the body. The muscle segments are intersected by septum by connective tissue (myosepta). The muscles on both sides of the body are arranged alternately with comb teeth together. As a result, when swimming, the Pangasius swim, its body bends along the horizontal plane. Amphioxus is widely distributed in the shallow waters of the ocean, and Qingdao and Xiamen in China are their primary habitats. In addition, there are coasts of Southeast Asia and coasts of California and Florida, Norway, the Mediterranean and Africa. Due to its rich nutrition and delicious taste, Van Xuong fish is considered a delicious traditional dish in Southeast Asia. Van Xuong fish is 3 to 5cm long, the morphology is very strange. The long and flattened body looks almost like a burden. The whole body color is pink, semi-transparent, the parallel longitudinal muscle fibers can be seen. They have no scales, no fins, no vertebrae, and their internal organs are just a rhythmic, rhythmic, complex. No senses like eyes, nose, or ears. There is no differentiation to the digestive tract. Apart from the mouth and throat, just a piece of intestine that leads straight to the anus. Van Xuong fish often follows tidal water to swim in estuaries where the seabed is shallow, almost unable to defend themselves but capable of penetrating into the ground. Their lifespan is about 3-4 years, they often bury half of themselves in the sand, while the other half is exposed to the plankton from the river. Their muscles are less differentiated, so they can only move in water by simple bending movements. When not moving they often bury themselves in the sand. The way of respiration of Van Xuong fish is similar to that of fish. They vibrate to inject capillaries (mouth tassels) to carry the stream of water from the gill slits. The wall of the gill slot has many blood vessels, where gas exchange occurs.

Bright Side brings together 10 rare creatures that are on the brink of extinction. Global mountain gorilla Currently the mountain gorilla has increased to about 1,063. They can only be found in protected forests. This is evidence that conservation efforts can bring a species back on the brink of extinction. However, illegal human hunting remains a major threat to the fauna of Bwindi-Sarambwe. Sao la The saola species was discovered in the Annamite forests of Vietnam. The main threat to saola is hunting activities and environmental climate impacts. That is why many conservation organizations have collaborated to create a safe environment for them in nature. Animal with dunnart bag This tiny creature can only be found on Australia’s Kangaroo Island, with an estimated population of less than 500. The widespread cleaning of the vegetation by humans has put the dunnart in a very dangerous situation. In addition, wildfires in Australia in 2019 and 2020 have burned 95% of the species. That is why a closed sanctuary was created to keep dunnart and other endangered species safe. Iberian lynx This rare species can only be found in the jungles of southwest Spain. From 1985 to 2001, their population decreased by 87%; So far, there are about 400 lynx in the wild. Their natural habitat continues to be destroyed by new highways and cut down trees. Black-footed ferret While people thought they were extinct, tiny creatures have proven to still exist. However, their population is rapidly declining due to disease and the loss of their natural habitat. Their total population is estimated at around 370 in the wild. Massive restoration efforts by many federal agencies and zoos have provided space for the weasels to survive. Gharial crocodile In 2010, only 15 crocodiles were found in the Gandak River in Bihar. That’s why in 2014, a conservation initiative freed 30 crocodiles from captivity and returned them to the river, and their population began to increase. Kakapo For the first time in 70 years, the kakapo population is increasing with about 213 species of birds existing. Only during the 2018-2019 breeding season, 71 young survived, which is a record number for this species. The recovery team tries to make sure the birds stay healthy and protected from infection. Their next goal is to find a good habitat for the birds as disease is their main threat. Canadian harbor seals Found in Quebec, this is the only species of its kind that can only survive in fresh water thanks to fish. To date, only more than 100 live in the area. The cause can be attributed to human hunting. Also, in many cases, seals get trapped in their gears and cannot free themselves. Leopard Amur This leopard has found a way to survive in the jungle in the Russian Far East. They live up to 15 years in the wild and more than 20 years in captivity. They have an amazing ability to run very fast and jump high. However, the loss of habitat and human activity has reduced their number to about 84 individuals. Vaquita dolphin This very rare marine mammal was discovered only in 1958. However, in recent years, vaquitas dolphins have been victims of illegal fishing activities. They are often trapped in fishing nets. That is why their population is only about 10 in the Gulf of Mexico. They can be found in shallow water but will quickly swim away if a boat approaches them.