The first animals on earth. When the first animals appeared, was the Earth an ice ball? The origin of animals on earth

First life

It's hard to believe, but on planet Earth there are still those very first organisms that played the greatest role in the further evolution of living nature. Scientists knew about them as early as the 18th century, but only in the 30s. In the 20th century, the veil of origin and the mystery of their formation were opened. We are talking about stromatolites.

Stromalites

Stromatolite (from the Greek stromatos - bedding, lithos - stone) is nothing more than a dense layered formation in the strata of limestones and dolomites, resulting from the vital activity of colonies of blue-green algae and other microorganisms. Stromatolites have been found on Earth since the Proterozoic, and today it has been established that the most ancient representatives can boast an age of about 3.5 billion years. Moreover, these same representatives have not changed a bit since those times.

In the 30s. The 20th century witnessed one of the most remarkable events in classical biology. On the littoral of Shark Bay (Australia) and on the Atlantic coast of the Bahamas, small reef structures of a previously unknown type were found. Upon closer examination, these turned out to be modern stromatolites!

The result of the activity of cyanobacteria

It was then that it became clear that stromatolite is formed as a result of the vital activity of a unique prokaryotic creature - a cyanobacterial mat. The cyanobacterial mat is a multilayer "carpet", up to 2 cm thick. It consists of cyanobacteria and other microorganisms. But in addition to the fact that the mat consists of layers, they perform different, but strictly distributed, functions. Thus, it is a full-fledged living organism, each part of which clearly performs its functions, and further research has shown that the cyanobacterial mat is one of the most balanced ecosystems in nature.

Stromatolites live in extreme conditions - in caves, very salty lakes and valleys, as well as in hot springs. And this is not surprising, because the conditions of life on Earth were just such, extreme, 3.5 billion years ago. And only thanks to the photosynthetic work of cyanobacteria, the modern atmosphere is rich in oxygen. Here they are amazing, the first living organisms!

The evolution of life on the planet began more than three billion years ago, some scientists say that even more than four billion years. It was then that the first organized ecosystems arose, however, these were microbes and bacteria, and mammals were still very far away. So what were the first animals on Earth?

The very first

The oldest traces of animal life on Earth are about a billion years old, and the oldest fossils of the animals themselves are about 600 million years old.

The first animals that appeared on the planet were microscopically small and soft-bodied. They lived on the seabed or in bottom silt. These creatures could not be petrified, so the only indication of their stay on Earth is the remains of their holes or passages. The individuals were very resilient, it was they who gave rise to the Ediacaran fauna - the first known animals on the planet.

Ediacaran fauna: light at the end of the Vendian tunnel

The Ediacaran fauna takes its name from the Ediacaran Hills that are found in Australia. Here, in 1946, unusual fossils were discovered, outwardly somewhat similar to modern jellyfish, worms and corals. They were small - an average of 2 centimeters in diameter.

At first, scientists decided that the find belongs to the Cambrian period: it was then that the rapid development of the animal world began (approximately 570 million years ago). But upon closer examination, it was possible to establish that these fossils are even older and belong to an earlier period - the Vendian. This was a real discovery, since no one knew for sure whether life existed during this period.

Then representatives of the Ediacara fauna were found in different parts of the world: in Namibia, Russia, Greenland. But despite the findings, biologists are still trying to figure out what happened to them.

This is what one of these ancient animals, Kimberella, supposedly looked like:

Scientists believe that these are the direct ancestors of modern jellyfish and mollusks.

What did the Ediacarans look like?

The structure of the first animals in the world was the simplest: they did not have limbs, heads, tails, mouths and digestive organs. Ediacaran creatures did not lead a particularly bright life)) at that time the planet was safe, there were no predators yet, so they didn’t even have anyone to defend themselves from.

It is assumed that they simply absorbed organic matter from the water with their whole body. Moreover, some of them were symbiosis with algae, and outwardly, many of the creatures were very similar to plants.

So, for example, the largest creature was dikinsonia.

Some individuals reached a meter in length, but usually did not exceed one centimeter in thickness. They had a flat, bilaterally symmetrical corrugated oval body. Such a rug.

Scientists have not decided which group it belongs to: some consider it the ancestor of animals, someone says that it is a kind of mushroom, and still others claim that it generally belonged to a class of creatures that do not exist today in the kingdom of nature. And her modern relatives were never found.

And what happened after the first animals in the world?

The next period in the history of the development of life on Earth is called the Cambrian. It began about 570 million years ago and lasted about 70 million years. It was here that an astonishing evolutionary explosion took place, during which representatives of most of the major animal groups known to modern science first appeared on Earth. And this happened due to good climatic conditions.

In the Cambrian period, huge plumes and continental shoals existed on the planet. There were ideal conditions for life: the bottom, covered with a layer of soft silt, and warm water. A lot of oxygen has already formed in the atmosphere (although much less than now). The development of hard land covers led to the emergence of new life forms, such as arthropods - the first arthropods.

Animals needed new ways to protect themselves from new highly organized predators. As a result of evolution, creatures developed means for protection, respectively, predators had to develop new methods of hunting in order to overcome the resistance of the victim.

During the Cambrian period, the sea level repeatedly rose and fell, species died out, others came in their place, who had to adapt to new living conditions and ways of subsistence.

The animal world became more diverse, and more and more populations could exist next to each other without claiming the food resources of their neighbors.

We all know from school that many of the ancient animals that once inhabited the planet have long since died out. But did you know that now the Earth is inhabited by animals that have seen dinosaurs. And then there are animals that have been around longer than the trees these dinosaurs ate the leaves from. At the same time, many of these ancient representatives of the fauna have not changed much over the millions of years of their existence. Who are these old-timers on our Earth and what is so special about them?

1. Jellyfish

The first place in our “rating” is rightfully occupied by jellyfish. Scientists believe that jellyfish appeared on earth about 600 million years ago.
The largest jellyfish that a person caught was 2.3 meters in diameter. Jellyfish do not live long, about a year, because they are a delicacy for fish. Scientists are puzzled over how jellyfish perceive nerve impulses from the organs of vision, because they do not have a brain.

2. Nautilus

Nautiluses have lived on Earth for over 500 million years. These are cephalopods. Females and males differ in size. The nautilus shell is divided into chambers. The mollusk itself lives in the largest chamber, and uses the rest of the compartments, filling or pumping out biogas, as a float for diving to depth.

3. Horseshoe crabs

These marine arthropods are rightfully considered living fossils, because they have lived on Earth for more than 450 million years. To give you an idea of ​​how long this is, horseshoe crabs are older than trees.

It was not difficult for them to survive all the known global catastrophes, practically without changing outwardly. Horseshoe crabs can rightfully be called "blue-blooded" animals. Their blood, unlike ours, has a blue color, because it is saturated with copper, and not with iron, like human.
Horseshoe crab blood has amazing properties - when it reacts with microbes, clots form. It is in this way that horseshoe crabs make a barrier against microbes. A reagent is made from the blood of horseshoe crabs and medicines are checked for purity with its help.

4. Neopilins

Neopilina is a mollusk that lives on Earth for about 400 million years. He has not changed in appearance. Neopilins live at great depths in the oceans.

5. Latimeria

Latimeria is a modern fossil animal that appeared on our planet about 400 million years ago. During the entire period of its existence, it has not changed much. At the moment, the coelacanth is on the verge of extinction, so the catch of these fish is strictly prohibited.

6 Sharks

Sharks have existed on Earth for over 400 million years. Sharks are very interesting animals. People have been researching them for many years and never cease to be amazed at their uniqueness.

For example, shark teeth grow throughout life, the largest sharks can reach 18 meters in length. Sharks have a wonderful sense of smell - they smell blood at a distance of hundreds of meters. Sharks practically do not feel pain, because their body produces a kind of "opium", which dulls pain.

Sharks are amazingly adaptable. For example, if there is not enough oxygen, they can “turn off” part of the brain and consume less energy. Sharks can also regulate the salinity of the water by producing special means. The vision of a shark is several times better than that of cats. In dirty water, they see up to 15 meters away.

7. Cockroaches

These are the real old-timers on Earth. Scientists claim that cockroaches have inhabited the planet for more than 340 million years. They are hardy, unpretentious and fast - this is what helped them survive in the most turbulent periods of history on Earth.

Cockroaches can live for some time without a head - because they breathe with the cells of the body. They are excellent runners. Some cockroaches run about 75 cm in a second. This is a very good result for their height. And their incredible endurance is evidenced by the fact that they withstand radiation radiation almost 13 times more than a person.

Cockroaches can live without water for about a month, without water - a week. Their female retains the male's seed for some time and can fertilize herself.

8. Crocodiles

Crocodiles appeared on Earth about 250 million years ago. Surprisingly, at first crocodiles lived on land, but then they liked to spend a significant part of their time in the water.

Crocodiles are amazing animals. They don't seem to do anything for nothing. To facilitate the digestion of food, crocodiles swallow stones. It also helps them dive deeper.

In the blood of a crocodile there is a natural antibiotic that helps them not to get sick. Their average life expectancy is 50 years, but some individuals can live up to 100 years. Crocodiles are not trainable, and they can be considered the most dangerous animals on the planet.

9. Shields

Shields appeared on Earth during the dinosaur period, approximately 230 million years ago. They live almost all over the world, except for Antarctica.
Surprisingly, the shields have not changed in appearance, only they have become smaller in size. The largest shields were found 11 cm in size, the smallest - 2 cm. If hunger sets in, cannibalism is possible among them.

10 Turtles

Turtles inhabited the Earth approximately 220 million years ago. Turtles differ from their ancient ancestors in that they have no teeth, and they have learned to hide their heads. Turtles can be considered centenarians. They live up to 100 years. They perfectly see, hear, have a delicate scent. Turtles remember human faces.

If the temperature in the nest where the female laid her eggs is high, females will be born, if it is low, only males will be born.

11. Hatteria

Tuatara is a reptile that appeared on Earth over 220 million years ago. Tuataria now live in New Zealand.

Tuatara is similar to an iguana or lizard. But this is just a resemblance. Tuataria established a separate detachment - beakheads. This animal has a "third eye" on the back of its head. Hatterias have slowed down metabolic processes, so they grow very slowly, but they easily live up to 100 years.

12. Spiders

Spiders have lived on Earth for over 165 million years. The oldest web found in amber. Her age became 100 million years. A female spider can lay several thousand eggs at a time - this is one of the factors that helped them survive to this day. Spiders have no bones, their soft tissues are covered with a hard exoskeleton.

The web could not be made artificially in any laboratory. And those spiders that were sent into space spun a three-dimensional web.
It is known that some spiders can live up to 30 years. The largest known spider is almost 30 cm long, while the smallest is half a millimeter.

13. Ants

Ants are amazing animals. It is believed that they have been living on our planet for more than 130 million years, while practically not changing their appearance.

Ants are very smart, strong and organized animals. We can say that they have their own civilization. They have order in everything - they are divided into three castes, each of which is engaged in its own business.

Ants are very good at adapting to circumstances. Their population is the largest on Earth. To imagine how many there are, imagine that there are about a million ants per inhabitant of the planet. Ants are also long-lived. Sometimes queens can live up to 20 years! And they are amazingly smart - ants can train their fellows to find food.

14. Platypuses

Platypuses have lived on Earth for over 110 million years. Scientists suggest that at first these animals lived in South America, but then they got to Australia. In the 18th century, the platypus skin was first seen in Europe and considered ... a fake.

Platypuses are excellent swimmers, they easily get their own food from the river bottom with the help of their beak. Platypuses spend almost 10 hours a day underwater.
Platypuses have not been bred in captivity, and there are quite a few of them left in the wild today. Therefore, animals are listed in the International Red Book.

15. Echidna

Echidna can be called the same age as platypuses, because it inhabits the Earth for 110 million years.
Echidnas are like hedgehogs. They boldly guard their territory, but in case of danger they burrow into the ground, leaving only a bunch of needles on the surface.
Echidnas do not have sweat glands. In the heat, they move little, in the cold they can hibernate, thus regulating their heat transfer. Echidnas are long-lived. In nature, they live up to 16 years, and in zoos they can live up to 45 years.

I wonder if a person can live on Earth for so long?

In order to answer this far from simple question, it is necessary to analyze a certain amount of theory. I should also note that there is simply no single answer to this question, so I will try to consider the most popular hypotheses.

Who are the animals

As I said above, in order to improve the quality of perception of information, it is necessary to study a certain amount of theoretical information, namely the definitions of terms. An animal is a special kind of organism, which, in comparison with others, is more independent and independent. The most developed animal on planet Earth is, oddly enough, man. Man is a higher being who has absolute independence from other individuals and is guided not only by his natural instincts, but also by his own opinion and thinking.

How did the first animal appear and where did it come from

After learning a certain amount of theory, I can proceed directly to the answer to the question asked.

1. The first and main hypothesis is that the animal appeared as a result of mutations of bacteria, which later turned into animals familiar to us. Such a theory cannot be considered unambiguously correct, because a person does not have weighty facts in favor of this theory.
2. Also at the moment, the hypothesis of divine origin is popular. This theory cannot be confirmed or refuted in any way, because there is no evidence and cannot be.
3. There is also a theory of alien entry of some species of animals, which later multiplied and turned into animals familiar to us. Such a hypothesis has a place to be, because there are multiple traces of meteorites on the planet.

It is simply impossible to say which animal was the first, because people do not have any data on this matter.

In conclusion, I can say that humanity has not yet confirmed a single theory, so you can make any of your hypotheses based on basic knowledge, which will also have its own probability of existence.