The evolution of insect swarms from XNUMX million years ago

Chapter 117 Migration and Freshwater Ecosystems

the other side.

The huge figure of another pioneering female swung its five pairs of paddling legs and swam in the gradually becoming turbid water.

In the sensing organ, the salinity of the surrounding seawater is getting lower and lower, which means that this pioneering female is gradually approaching fresh water.

In the compound eyes, the fish in front were swaying vaguely, and they entered the mouth of the river - yes, this may be the earliest migration phenomenon in history.

Those are sticklebacks. Although it was not the creepy Shen's stickleback that Lin Yi had encountered in his previous life, but a species that he could not name, it still had a similar structure of two spiny dorsal fins.

Behind the stickleback shoals that gather for migratory breeding, there are a large number of medium-sized cryptid horseshoe crabs that are good at swimming. Just like the various predatory fish that chased the migratory fish schools in later generations, they preyed on the gathered fish. A school of fish in one place.

The figure of the horseshoe crab is waving its sickle limbs covered with long thorns at the outermost edge. Every time the ferocious sickle limbs are closed, they can penetrate the bodies of several stickleback fish and string them on those long thorns like skewers of candied haws.

Some large horseshoe crabs are not even satisfied with preying on sticklebacks, but instead kill small horseshoe crabs. The blue horseshoe crab blood and the bright red fish blood surged together.

Some were even more daring and approached the workers who were opening up the mother's side, looking at them with malicious intent.

But soon, the arriving soldiers showed off their sickle limbs covered with blades and thorns, causing these guys to retreat - even though the veteran feathered horseshoe crab from the previous dynasty was not necessarily the opponent of the rising star Hunhai horseshoe crab. But the second-generation soldier improved on the feather-winged horseshoe crab template is enough to easily kill the mixed sea horseshoe crab.

The stickleback group gradually entered fresh water, and the trailing horseshoe crabs and horseshoe crabs also receded due to difficulty in adapting to the lower salinity environment. The sticklebacks were safe - for the time being.

There may not be many predators in fresh water at this time - compared to shallow coral reef waters that appear to be rich but are actually unbearable, the competitive pressure in fresh water is much smaller, especially in this freshwater ecosystem. An era that was just taking shape.

This may be why in every era, various fish choose to swim upstream and enter the river to give birth to their offspring. When the young fish grow up, they return to the ocean to survive.

The pioneer mother and all the workers have an osmotic pressure adjustment system that can adapt to both seawater and fresh water, so they can continue to follow the stickleback school, enter the river, and explore forward.

In fact, Lin Yi came to inspect the shape of the freshwater ecosystem, and to take a look at the situation on land, and consider whether he could go to land - he already had thoughts on how to protect his own existence in both ways. Some vague thoughts.

The school of sticklebacks continued to move forward, followed closely by the huge body of the pioneer mother. Soon, the fish arrived at their destination - to be precise, the last obstacle in front of the destination.

In front of us, countless huge rocks blocked the river, forming a natural embankment. The water flowed straight down for less than two meters from above. It was not spectacular, but for the sticklebacks, it became a big obstacle on their migration path.

The sticklebacks swung their primitive tail fins, jumped out of the water with all their strength, and jumped upwards. For a moment, they had the momentum of later generations of salmon migrating through the rapids.

The first stickleback jumped onto the boulder. Although their pectoral fins were primitive and not as good as those of later generations of lobe-finned fish, they were still stronger than most ray-finned fish. They barely flapping around and brought the pupae with them, and the pupae entered the front.

Above the rocks, Lin Yi once again saw the figure of a new species. It is a chelicerate arthropod with a body size of about tens of centimeters. It has a scorpion-shaped body similar to that of a plate-footed horseshoe crab, but in addition to the pair of small chelicerae, there is also a pair of large pointed claws, and the end of the hind body is as slender as The scorpion tail also has curved stings, which looks very much like a scorpion in every aspect.

Lin Yi was startled when he saw their figures - they didn't look like scorpions, they just looked like scorpions.

Later generations of molecular biology speculated that, as the oldest group among arachnids, Scorpionida was likely to have separated from Platypodia in the Ordovician.

Although the appearance of early scorpion or arachnid species probably had no characteristics, no fossils were found in later studies, or if they were discovered, they were too unpopular. Lin Yi did not know about them in his previous life.

Moreover, Lin Yi had never seen it before in the Ordovician and the Ordovician Stone Nest Group, or he had not recognized it before, and his sense of existence was too low.

Real scorpions have indeed appeared in the Silurian period. For example, the famous thunder scorpion, the "Brondu scorpion", can reach one meter in length. If it is confirmed to be a scorpion species, it will be the largest ever seen. Scorpion, the late Silurian successor to the horseshoe crab niche.

But the problem is, that was from the late Silurian period to the early Devonian period. Nowadays, horseshoe crabs are still living well, and the ecological niche is not freed up for scorpions. Unexpectedly, the scorpion had already appeared at this time, and already had the appearance of the scorpion of later generations.

Lin Yi speculated that they probably developed first in freshwater ecosystems with low competitive pressure. After the horseshoe crabs declined due to the recession, they shared the former's predator ecology with the chelated horseshoe crabs, which also have claws. Bit.

But now, apart from being smaller in size, these scorpions are very similar to Thunder Scorpions in all aspects of appearance. Except for their wider bodies and flatter abdomens, they are just like smaller Thunder Scorpions.

Considering that they appeared earlier, Lin Yi simply and crudely called these scorpions that he didn't know whether they would be discovered by later generations. Anyway, the scorpions he didn't know about were the first thunder scorpions.

Although it is not advisable to randomly identify one's ancestors, I don't know if this thing is Lin Yi, the ancestor of Thunder Scorpion later, but firstly I can't think of a suitable name, and secondly no one talks about him these days, so he just shows off like this. The call went on.

The appendages of the First Thunder Scorpions are closer to the legs of later generations of crabs, with long and pointed ends and no forks, suitable for walking on the sand. At this time, it is a bit reluctant to step on the boulders, but the temptation of food still makes them continue to approach unsteadily. .

The chelicerae - to be precise, the large chelicerae evolved from the pedipalps, waved, approached a stickleback pupating on a stone, and picked up the defenseless stickleback. At the same time, it is as slender as a scorpion, no, the scorpion's tail is curved, and the poisonous needle at the end pierces the stickleback's body fiercely.

Dark red blood oozed out, and the stickleback's body slowly stopped struggling. The large claws evolved from a pair of pedipalps tore and tore at the claws on both sides of the mouth, cutting off pieces of the stickleback's flesh and blood and sending them into the mouth.

The smell of blood spread, and more Thunder Scorpions were attracted by the smell, and joined in this gluttonous feast where the prey had no ability to resist, just like the brown bears that ambush the fish migration routes in later generations.

Soon, as more and more Thunder Scorpions arrived, the migration caused by reproduction turned into a bloody massacre.

However, behind the fish school, the huge figure mixed in was also slowly approaching, approaching the Thunder Scorpions who were still immersed in eating.

　There are too few well-known species in the Early Silurian, and there is no information. There may be a large number of species that crossed over.

　　In addition, because authors who don’t know what Qidian thinks have to spend money to read paid chapters of their own books, the picture has been posted in the group recently.

　　

　

(End of this chapter)