In 2021, many places in the United States issued warnings to remind the public to take defensive measures, because about 30 billion cicadas will break ground at the same time within a few days.
If it's just one or two cicadas stopping on the nearby trees and calling non-stop, we will treat them as our home in the summer. ButIf 30 billion cicadas appear at the same time
It will not be a huge ** meeting, but a disaster. These cicadas are no ordinary summer homeRather, it is a cyclical cicada that has been dormant for 17 years before being unearthed.
Seventeen-year-old cicadaIt is similar to the appearance of the cicada, with a body length of about 3 cm, slightly larger than the average cicada, a pair of slightly larger compound eyes on the head, and three dot-like single eyes arranged in the middle to form a triangle.
The body is black, with two pairs of thin, transparent wings, brown, large forewings and small hindwings, and the flight distance is not long, which looks like a small torch. It doesn't bite, but the noise pollution is serious, and the collective death and fall will also bring environmental pollution.
The seventeen-year-old cicada is an insect class-Hemiptera-cicada family-periodic cicada genus. The cyclical cicada is a genus of cicadas in North America, there are 7 species of cyclic cicadas, and their life cycles are 17 or 13 years.
So 3 of them are:Seventeen-year-old cicada, 4 kinds forThirteen-year-old cicada。AsOne of the oldest insects in North AmericaThe long dormant cycle of the periodic cicada is always surprising.
They're inNymphsIt lives underground and lives by sucking the sap from tree roots. How long this hibernation lasts depends on whether they are thirteen or seventeen year olds.
At the end of the dormant period, a large number of nymphs will break through the soil and become dense like flowing water. This "water" flows onto the tree and molts into winged adults.
After molting, the cicadas have white bodies and translucent wings, and their bodies are still very soft, so they continue to stay in the trees for one night, waiting for their bodies to gradually harden and their wings to slowly stretch.
During the day, the cicadas, whose exoskeletons are completely hardened, begin to call, expressing the joy of feeling the sunlight and air. Different species of periodic cicadas have different calls.
When the opposite sex approaches, the male cicada will transform into another unique call, courting with superb talent. If the female cicada also takes a fancy to this young man who sings well with a tenor, she will gladly respond.
The cicada that completed the courtship got married on the spot and began the baby-making project. After mating, the female cicadas dig gaps in the branches and lay eggs inside.
After the nymphs break out of their shells, they will return to the ground, burrow between the roots of trees, and continue the long hibernation process, until many years later, they will break through the soil again and complete the relay of the next generation. The life cycle of eggs, nymphs, and adults continues.
Although the overwhelming cries of the periodic cicadas disturb the purity of the jungle, the good neighbors of these jungles do not complain because they disturb the people, but are grateful for the food.
These praying mantises, squirrels, birds, and other neighbors love this fragrant protein. Some clumsy cicadas tend to fall to the ground, and animals such as turtles that can't climb trees also pick up leaks under the trees and feast on them.
Cicadas that have completed the task of mating and reproducing will die, and their corpses will not only serve as food for their neighbors, but also rot in the soil and become a food for the earth.
During the seventeen-year period of cicada abundance, the number of birds that feed on them increases rapidly, and after 12 years it begins to decline, reaching its lowest point in the 17th year.
This is a strategy of the cicadas, which design an orbit for the birds, so that the number of birds is greatly reduced when the next batch appears.
The mathematical talent and survival talent of the periodic cicada is a miracle of nature. A closer look reveals that whether the cyclical cicadas have been dormant for 13 or 17 years, or shorter years, their underground activity cycle is prime.
Take 17 years, for example, except for 1 and itself, there is no number that is divisible by it. Why can't there be 16 so that in addition to 1 and 16, there are such divisible composite years?
Let's start with the annual cicada, which appears every summer, and the predators can eat fresh every year, and since the number is not a sudden increase or decrease, their numbers are relatively stable with those of the predators.
If it's two years old, the predators will have a full meal in the first year, and the cicadas won't come out in the second year, and the predators who love to eat the cicadas will have to go hungry. In this way, the longer they are dormant, the fewer these predators will starve. By the time they are unearthed, the natural predators will naturally be reduced.
If the dormant period were a composite number, this would not be the case. Take 16 years as an example, 16 years has a factor.
If the predator reproduction cycle is 2 years, then the 16th year of the cicada will meet the 8th generation of these predators in large numbers. Predators with a 4-year breeding cycle, the 4th generation of their large reproduction will be a great threat to these 16-year-old cicadas.
If the cicada's dormant cycle is 17 years, then it will take at least 34 years to meet a large number of offspring of a predator with a 2-year reproductive cycle. It takes 68 years to meet a large number of descendants of predators with a 4-year reproductive cycle.
To put it simply, when these cicadas are unearthed, they happen to encounter the shortest time for predators to reproduce in large numbers, which depends on the minimum common multiple of the periodic cicada hibernation time and the predator's reproduction cycle.
At this time, the prime number period of the periodic cicada shows its advantages. Predators are complex to reproduce, and the sheer number of predators is just to be avoided as much as possible.
Although cicadas have a hibernation cycle of 17 years, it is somewhat amazing that all cicadas can appear at the same time. Just like the age of human beings going to school is sixteen years old, but not all human beings go to school on the same day, because there are differences in each other's growth.
There are also differences in the growth of periodic cicadas, and it may also appear at other times, but because they are born at the wrong time, a smaller number of groups appear, and ** eats them.
This brings us to the second survival strategy, "saturation escape". To put it simply, when a large number of cicadas appear together, even if there are many predators who have been eyeing them, the numerical advantage of the cicadas is there, some are eaten, and some can always survive.
And those cicadas who did not follow the "saturation escape", the final result was the total annihilation. After this screening, the surviving cicadas all lay eggs at the same time, lay dormant underground at the same time, and were unearthed at the same time.
Cyclical cicadas are mostly 13 and 17 years old, which is nature's elimination choice. Those who are not adapted to the cycle too long or too short are eventually eliminated, so that the last survivors are thirteen and seventeen years of adaptation to the environment.
Scientists speculate that the emergence of periodic cicadas should be 1.8 million years ago. There were many ice periods, and these sudden ice spells deprived the summer of heat.
Most of the growth cycle of cicadas is in the soil, and summer is the day when they are actively unearthed. The cicada, sensing that something was wrong, continued to hide in the soil and successfully escaped.
As a result, the cicada's emergence cycle has been extended, the exposure time has been reduced, and the cold summer has been avoided to the greatest extent, and the population has been preserved the most.
Studies have shown that if there is a cold summer every 50 years in 1500 years, and the cicadas unearthed every 7 years, there is a 7% chance of survival. Cicadas unearthed every 11 years have a 51% chance of surviving. Cicadas unearthed every 17 years have a 96% chance of surviving.
Therefore, most of the cicadas with a short dormant period are frozen to death, and the cicadas that have been dormant for about 17 years, such as 16-18 years, have the highest survival rate.
Each group of 17-year-old cicadas has a 4% chance of encountering a cold summer when unearthed, and during the long ice age, there are many groups of 17-year-old cicadas dying in this 4% chance.
The seventeen-year-old cicada is not the pride of the sky, maybe there are longer 20 years or 30 years of cicadas after it, but the life span of insects has a limit, although the longer the dormant time, the easier it is to survive the disaster period, but the life span of insects is limited, and they die of old age before they have seen the sun, which is really sad.
The test of the environment, the unchanged lifespan, the superposition of these factors, makes the seventeen-year-old cicada have a survival advantage. The 13-year-old cicadas can compete with the 17-year-old cicadas because they live farther south and can absorb more solar heat, and the cold summer is less harmful to them.
Therefore, although the dormancy period of the thirteen-year-old cicada is shorter than that of the seventeen-year-old cicada, its survivability is not weaker than that of the seventeen-year-old cicada. Nature is a wonderful mathematician, and these cicadas are the top masters of survival.