Hello everyone, it's time for "Tao Ge Blind White Life" again, and today we continue to nag about the evolutionary history of fish.
In 1952, Jensen, then Governor-General of the Union of South Africa, ordered a helicopter to be sent to the coastal docks on an outrageous mission — to escort a fish.
When the helicopter returned to the airport after completing its mission, Jensen personally went to greet him. Seeing this fish that had been searching for 14 years, Jensen's first words were: It turns out that our ancestors looked like this.
The fish that made Jensen sigh is called the speartail fish, which is the protagonist of today's article, belonging to the subclass of finfish.
Living fossil among living fossils: speartail fish
The biological community had concluded that they had been extinct 65 million years ago, but in 1938 a speartail fish was caught by African fishermen. When it was learned that there was still a live speartail fish, the South African government of the country of the incident did not hesitate to send a naval search, and finally found the second one 14 years later, so there was the scene at the beginning of the article.
It is the fish that we humans should be most thankful for, because theoretically, every land vertebrate, including cattle and sheep, lions and tigers, birds and even you and me, has to call the fin fish "ancestor" - if it had not been for the fact that it took that meaningful small step to land with its weak fins 360 million years ago, you would not have had the opportunity to swipe your mobile phone to brush your headlines.
So why do finfish risk their lives from the water to live?
Why did they, after creating a landing hegemony, instead turn back to the dark deep sea?
Can the speartail fish of that lineage reproduce the landing feats of the ancestral flesh-finned fish and deduce a new chapter of species under the eyes of humans?
To know the answers to these questions, one has to go back 400 million years.
1
In the Silurian period more than 400 million years ago, all the creatures in the water surrendered to the tail thorns of the scorpion tribe's armor, but the fish quietly accumulated potential in the long years, and in the subsequent Devonian Jedi counterattack, in the end, the shield fish represented by the Deng's fish completely shredded the rule of the scorpion tribe with sharp teeth, declaring that the fish had ascended to the throne of the ocean overlord. (For detailed procedures, please refer to my previous article, click direct)
Dunn's Fish
When the old and new overlords alternated, the meat fin fish took advantage of the fish to soar up to the ninety thousand miles of east wind and took advantage of the trend.
Meat fin fish
But the luck of the times does not mean the luck of the individual, compared with other happy fish in the Devonian period, the finfish found that its life was not good, in a word - it was slow to start!
If the struggle for supremacy over the seas is considered a war, fish are like a well-organized medieval army in which each branch of the armed forces clearly performs its duties.
The heavy responsibility of fighting the former rulers of the Scorpion Clan fell on the shoulders of the brave shield fish - heavy infantry;
The cunning and swift Cthulhu people of the middle ecological niche, the cartilaginous fish represented by the rift shark are at ease - light cavalry;
Sanction the old armored fish and other small animals left behind by the former dynasty of their own people, and the light and courageous spiny fish take the lead - the gendarmes;
Spiny fish
This war machine operates day and night, helping fish dominate the ocean, but also brings an embarrassing question: Where is the piece of cake that belongs to the finfish?
The difference in body structure doomed the finned fish to be unable to take enough resources from the mouths of other fish, so the fin fish that had been wandering around the ocean for a long time but begged for an unbearably niche had no choice but to make a decision - they left the vast and fertile ocean with tears and went to the barren frontier: fresh water.
This place is different, lonely and lonely.
2
Although it cannot be compared with the powerful shield fish, the meat fin fish is after all a jawed fish that has been cared for by the Creator, so as soon as it comes to fresh water, the meat fin fish relies on the evolutionary advantage accumulated since the Silurian period to carry out indiscriminate slaughter of the surrounding creatures, so that the invertebrates once again feel the fear of being dominated by fish in the fresh water after the first defeat in the ocean.
Arthropods, led by scorpions, were preyed upon by fish during the Devonians
Almost completely replicating the dominance experience of shield fish in the ocean, meat fin fish are also racing in bite force and body size, in the middle and late Devonian period, the lungfish under the flesh fin fish body length of 5 to 8 meters, weighing about 2 tons, it is not only the ultimate nightmare of all small freshwater creatures, but also opened its abyss mouth to medium-sized predators such as pectoral spine sharks.
Lungfish hunt for pectoral ridge sharks
The Dunn's fish in the shield fish and the lungfish in the flesh-finned fish, the pair of jawed geminis, which bloom in the ocean and freshwater lines respectively, mark the supreme peak of the fish, and fully explain why the Devonian period is called the "Fish Age".
3
It is a pity that there is a real joy in the streams and mountains, and wealth has always been a crisis, and this sad sigh of Wen Tianxiang, a famous minister of the Southern Song Dynasty more than 900 years ago, was vividly reflected in the flesh fin fish at that time.
Although the idleness in fresh water makes the finfish forget the embarrassment of the past in the ocean, it also hides a huge hidden danger that can wipe out the dead people - the intermittent drying up of small rivers and lakes.
Every time a disaster comes, countless fin fish roll and struggle in the wet and muddy riverbed, watching the moisture on which they depend for survival evaporate little by little, they open their mouths and open and close the gills like crazy, hoping to get even a small mouthful of sweet oxygen to continue life, but the lack of moisture of the cheeks seems to have finished writing but forgot to wash the brush, sticking together, can no longer dissolve the oxygen in the water normally, these finfish can only helplessly wait to die in the mud swamp.
In this successive generations of heavenly punishment, some flesh-finned fish represented by the Yunnan Ken's fish were not willing to be reduced to fossils, and they began to carefully examine their own body structure, and finally found two huge rewards placed by the Creator.
First, their maxilla and mandible are not connected front and back, which makes the external nostrils that were originally on both sides of the head, only the olfactory function, can smoothly "drift" into the upper part of the pharyngeal cavity, forming the inner nostrils, which gives the finfish the ability to obtain oxygen directly from the air;
Second, compared with other fish, there are bones and muscles in the fins of meat fins, which is slightly bulky and makes the meat fin fish slightly inferior in the previous ocean inner volume, but it allows them to use their fins to support their bodies to move in the desperate situation of lack of water;
To escape the dried up mud pond, these finned fish staggered to shore with their incomplete new respiratory system and frail flesh fins, little by little, inch by inch, meter by meter.
The shallow sea carbonate rocks of the Polish Holy Cross Mountains, which may be the earliest evidence of the finned fish leaving the water
Perhaps some of them can only climb out of the ten meters and then exhaust their physical strength and sleep with hatred, and some can go further, but they can still only use the corpse of their own dehydration and death as a signpost for latecomers. But in the end, there are still finfish that have completed this long march of blood and tears paved by countless lives, and these chosen fish have successfully arrived at their new aquatic habitat and continued to multiply.
Again and again to escape from death, again and again to set off again, in this endless cycle of purgatory and nirvana rebirth, a certain fin fish was reborn and became the first terrestrial vertebrates that can live away from the water for a long time - tetrapods.
As a reward for the phoenix's fire, the Creator prepared a surprise package for the tetrapods on land—plants and invertebrates that preceded their landing.
These became an inexhaustible source of energy for the tetrapods, allowing them to successfully evolve into amphibians and reptiles.
Attacking finfish prey on arthropods
4
"Those fish that come ashore are no longer fish." - "The Three-Body Problem"
Perhaps remembering their predicament in the ocean tens of millions of years ago, or perhaps the evolution of the landing was too sad and painful, these tetrapods, at the first moment of gaining a firm foothold, stretched out their fangs and claws at all living beings in sight- including those "half-aquatic, half-terrestrial finfish" that moved slightly slower and did not have time to fully adapt to pure land survival.
Thus, the left and right branches of the shallow ocean, the blessings and misfortunes in the freshwater tides, and the encirclement and suppression of the same ethnic groups on the solid earth, let this part of the finfish that could have landed suddenly collapse at the full ecological level, and under the embattled, one of them huddled in the deep sea where there was no light, and meditated silently in the bitter cold place where almost all creatures were dismissed. The remnants of the finfish closed the evolutionary panel, feeding on small mollusks, no longer strengthening any skills or organs, and the only thing worth their effort was to regulate their metabolic rate—in times of food shortage, they could drastically reduce their metabolic rate and sink into deeper and safer seas in a state of near -hibernation.
A spear-tailed fish that stands motionless on the bottom of the sea
Looking back at the place where there has always been no wind, rain or sun, at this point, whether it is meteorites or volcanic waves in the outside world, they have nothing to do with the world-free finfish, which is why scientists have long believed that they have long been extinct - this surviving fin fish is really too good to find, until 1952, they reappeared in South Africa, allowing us humans to see their ancestors.
Although their appearance has not changed much compared with hundreds of millions of years, they have long lost the determination of their ancestors to live to die, and the finfish are tired of your natural choices, and they have lost their yearning for climbing land to expand their territory.
Hundreds of millions of years have not changed, too able to do
They will not know that the people who once bravely marched with them from the light cement swamp not only completely dominated the land and did not fall in the years that followed, but also sharpened the knife and extended the butcher's knife to the hometown ocean, and even evolved the pair of even fins that were originally used to escape into wings that flew high, soaring in the sky of the blue star.
Of course, this is another story, if you want to see, you can comment more likes and forward this article, if the data is good, I will continue to write.
I am Tao Brother, such a long article has been read, are you sure not to give me a concern?