Encyclopedia of popular science knowledge: "Time Knowledge"

Chapter 6 The masterpiece of nature - the biological clock (2)
Migratory birds move with the seasons.Every year at the turn of spring and summer, barn swallows and egrets fly from the south to lay eggs and reproduce, and then fly back to the south in autumn.At the turn of autumn and winter, wild geese and wild ducks fly from the north to the south, and then fly back to the north in the spring of the following year. This is from the breeding area to the wintering area, called winter migratory birds.

For countless centuries, migratory birds have been like this, and the birds return at this time every year.

Barn swallows build their nests under the eaves or under the beams, holding mud and grass stalks to form bowl-shaped nests.

"Pianpiantang Qianyan, see you in winter and summer." It raises eggs in the old land and feeds the chicks nearly 200 times a day. A pair of swallows have to catch hundreds of pests every day, swallowing about 6 pests in 10 months. ten thousand. "If you go back and forth for a while, you are still afraid of starvation in the nest. After [-] days of hard work, the mother becomes thinner and the chicks become fatter."

Where do swallows come from?Someone made up a beautiful myth, saying that the swallow came from "the country of black clothes", which is its hometown.

There is no Wuyi country, and the barn swallow comes from the Indian Peninsula, Nanyang Islands and other wintering places.

Every year, it flies from the south to the north, and first arrives in Guangdong, and then arrives in Fujian, Zhejiang, and the Yangtze River Delta in March. It has been seen in Shanhaiguan and other places in April, and then goes to Northeast China and Inner Mongolia.

Swallows correctly find their home habitat every year. "Looking at the return of the swallow", "I don't mind returning to the poor house", "flying into the homes of ordinary people".

The migration route of the yellow-breasted bird takes a tortuous route.In spring, yellow-breasted birds fly from the Indian Peninsula and the Indochina Peninsula to Siberia through my country, and then fly through Eastern Europe to Western Europe, where they build nests, lay eggs and reproduce.In autumn, the yellow-breasted bird followed this roundabout route and returned south to the Indian Peninsula and Indochina Peninsula.

Geese are winter migratory birds, and they migrate southward in groups every autumn and winter.There are two main flight routes: one route goes from the northeast of my country through the Yellow River and Yangtze River basins to the coastal areas of Fujian and Guangdong, and even reaches as far as the Nanyang Islands; the second route passes through Inner Mongolia, Qinghai, Sichuan, and Yunnan, and finally goes to Burma and India for wintering.

The ancient poems vividly describe the geese flying from the north to the south: "The geese fly high in the black moon", "the geese and snow are blown by the north wind", "the geese go out of the Hansai, and the geese return to the Hutian".Outside the Great Wall refers to the area north of the west of the Great Wall. In August of the lunar calendar, it begins to snow here, which is when the northern geese fly south.In the area west of Yumen Pass in Gansu Province, the messenger's grass cart was traveling in the desert in autumn, and saw wild geese flying south in snowy days, and the grass blowing in the wind.

Not only do geese in Asia migrate north and south, but so do geese in Europe and North America.

Whenever the autumn wind blows the fallen leaves, the geese in Northern Europe migrate south to Africa; the geese in North America migrate south to South America, and then fly back to their "hometown" in the spring of the following year.

On the vast land between the west of Lake Superior in North America and the Hudson Bay, there are large tracts of primeval forests, where the largest flock of eagles in the world lives.Every year in late autumn, when the climate turns cold, flocks of eagles fly to the south for the winter in groups, up to more than 25; after the warm spring, they fly back to the breeding area.

Strange to say, this group of flying eagles all migrated by the same route, and they flew along the coast of Lake Superior, forming a powerful "eagle stream" of activity, which seemed to be an invisible air corridor.When the eagle stream flew by, it covered the sky and covered the earth, like dark clouds overwhelming the top, and the sky suddenly became dark. It became a great spectacle in nature.

Golden bird migrations in North America fly in large circles.There are two types of golden birds, eastern and western. The eastern golden bird breeds in western Alaska and northeastern Siberia in spring, and flies south to Taiwan, Guangdong and Yunnan when it migrates south, with a flight distance of more than 4000 kilometers.Western goldenbirds nest and breed in Canadian forests, fly south in autumn, pass through the Labrador Peninsula, the Atlantic Ocean, Brazil, and spend the winter in the jungle grasslands of Argentina, fly north in spring, and return through Central America and the Mississippi River" home".

Storks migrate from Northern Europe, pass through the Mediterranean Sea, the Sahara Desert, and fly to South Africa to spend the winter.The flight time is about 3 months, and the flight speed is relatively fast.

The flying distance of Weng Niao is even more astonishing.People found that after a young bird hatched in Greenland in the Arctic Circle in summer, when it flew south, after many days and nights, it flew to West African countries tens of thousands of kilometers away from its hometown.

Sea fulmars lay eggs and reproduce during the polar day in the Arctic region. At this time, it is the polar night in Antarctica. After laying eggs, the sea fulmars hatched and flew to the south for the winter. At that time, Antarctica just started the polar day, and they flew even more. The annual return journey is 4 to 5 kilometers, and the destination can be found accurately every time.

Why do migratory birds only fly in spring and autumn?Biologists believe that external factors such as climate (including temperature, wind, snow, sunshine), food, etc. are closely related to seasons and have a significant impact on bird migration. In wintering areas, summer is extremely hot, which is not suitable for birds to lay eggs and breed. When they return to their hometown in the north, the winter in the breeding area is very cold, which is very unfavorable for the birds to forage and live. In autumn, they go south to overwinter.

Hairtail and octopus traveling from north to south
Hairtail, large yellow croaker, small yellow croaker and cuttlefish are known as China's four major marine products.Hairtail, large yellow croaker and small yellow croaker are all migratory fish, and they travel to and from different sea areas in the north and south as the water temperature changes with the seasons.

The hairtail is flat and strip-shaped, with a silvery white body, a large mouth and sharp teeth.It lives in the middle and lower water layers during the day and rises to the sea surface at night.When it swims, it does not rely on its fins to paddle, but swings its body from side to side as waves.

Every year around the beginning of winter, schools of hairtail fish that go south from the Yellow Sea, go north from the South China Sea, and swim inward from the deep sea "join up" near the Zhoushan Islands, where there is abundant food, forming a big winter fishing season in the East China Sea.They stay and stop from time to time, moving forward in zigzags, traveling hundreds of kilometers, batch after batch, as many as 70 batches, and the time is as long as 80 days.

my country's hairtail can be divided into two types: northern belt and southern belt.The ones in the northern ocean are called the northern belt, and they are physically strong.In winter, the northern hairtail migrates from the East China Sea to the north to the Bohai Sea, forming a spring fishing season.

After laying eggs, they begin to migrate southward in autumn to search for bait and come to the East China Sea.

The southern ocean is called the southern belt, and it is small and fat.In winter, the southern hairtail migrates to the South China Sea for the winter, and in the spring of the following year it begins to spawn and migrate, forming a spring fishing season.After laying eggs, they arrive near the mouth of the Yangtze River in autumn to search for bait and migrate.

During the spawning season, male and female hairtails shuttle back and forth in the sea, chasing each other. Females lay eggs and males ejaculate. One female can lay about 7 eggs, and the eggs are densely packed with the current.It only takes 4 days for the fertilized eggs to hatch into small hairtails a few millimeters long, like needlepoints and wheat awns.

Yellow croakers overwinter in the deep sea, migrate to the sea to spawn every spring, and migrate to the sea to find bait after spawning.

There are two types of yellow croakers: large yellow croaker and small yellow croaker. They are very similar in appearance but different in size.

Large yellow croakers are both afraid of heat and cold, so most of them live in the coasts of Zhejiang and Fujian all year round. They only appear in large numbers in winter and spring along the coast of Guangdong. From the coast of Jiangsu to the north, they are rarely seen.During the breeding season, they gather in dense groups and live in the middle layer of the offshore sea. The female fish keeps making "crack... cluck..." sounds. The whole spawning ground is very lively, just like frogs croaking in summer night.The sound is produced by the contraction of the abdominal muscles of the fish and the friction of the swim bladder.This is a means of courtship and information exchange among the same species.Large yellow croakers lay 10 to 100 million eggs each time.

The living habits of small yellow croakers are different from those of large yellow croakers. They hide under the water during the day, and at dusk and dawn, they swim to the middle and upper layers to look for food, eating fish, shrimp and shellfish.It is similar to the recipe of large yellow croaker, and the swim bladder can also make sounds.

The small yellow croaker has a much wider distribution range than the large yellow croaker, and there are distinctions between northern yellow croaker and southern yellow croaker.

In spring, the temperature of the Yellow Sea rises, and the small yellow croakers in the Yellow Sea wintering ground near Jeju Island travel in groups along the Shandong Peninsula to the Bohai Sea. Spawns and forages.

In autumn, the temperature of the Bohai Sea gradually drops, and the small yellow croakers leave the Bohai Sea together with their juveniles. In early winter, they return to the Yellow Sea Overwintering Field for the winter.

The small yellow croakers that winter in the southeastern coast of Zhejiang start to go north to the Zhoushan Islands or the coast of Jiangsu to spawn in spring, and a small part of them go south to the coast of Fujian to spawn, and then migrate to the East China Sea to spend the winter in the winter.

The migration of yellow croakers has certain rules, and the time and route are basically the same every year. People have mastered this rule and set huge nets on the spot to get a good fishery harvest.

The age of trees - annual rings

People judge the age of trees according to their "annual rings".So, what are annual rings?It is the ring formed by the stems of trees every year.

In temperate regions and tropical regions with dry seasons and rainy seasons, trees grow year after year, and the activities of cambium cells show regular changes due to differences in seasons and climates within a year.In spring, the weather gets warmer, nutrients are sufficient, and the division and growth of cambium cells are fast. The resulting xylem has larger cells, thin walls, many and large vessels, and less wood fibers. This is called early wood or spring wood; in autumn , the temperature gradually lowers, the nutrients decrease, and the division and growth of cambium cells slow down. The xylem produced has smaller cells, thicker walls, smaller and fewer vessels, and more wood fibers. This is called late wood or autumn wood.

The early wood is lighter in color and the late wood is darker. Together they form a ring, which is the wood formed by the tree in one year, called "annual rings".Annual rings, as the name suggests, are long rounds a year, and how many rings there are, you can know the approximate age of the tree.

Not all trees have annual rings, like monocotyledonous plants have no annual rings because they have no cambium.In the tropics, where seasonal changes are absent, the cells produced by the cambium differ little and annual rings are often indistinct.Sometimes, several growth rings can also be produced each year due to the rhythmic activity of the cambium.Therefore, to calculate the age of a tree based on the annual rings, the false annual rings must be removed, and only an approximate data can be obtained.

Annual rings—the unique "language" of trees not only tells the age of trees, but also records and reveals the changing conditions of the climate.Arizona State University was the first to establish a laboratory for the systematic study of tree rings. Scientists found through long-term observation and research that pine trees in the southwestern United States are particularly sensitive to climate change.In cold and wet years, the annual rings of pine trees grow very narrow.According to this rule, the local climate conditions long ago can be deduced.

It has been found that the pattern of annual rings has a certain relationship with temperature, air pressure and precipitation.Some people have drawn weather maps of North America in recent centuries based on tree rings.These weather maps are very similar to the results recorded by modern weather equipment.

In the 19th century, when a mining survey team crossed the western plains of the United States, they left a diary, recording their experience of severe cold and storms that year. Interestingly, according to the local tree rings, it also reflects this An unusual climate fact.

The thorny pine in the United States was discovered in the Southwest in the 19th century, and the number of this strange tree is very rare. In 1964, Curry, a student of the Department of Geography at the University of North Carolina, found the thorn pine while studying the glacier on Wheeler Peak.In order to collect circumstantial evidence and infer the age of the glacier's formation, he drilled several old trees with a perforator. He found that one of the old trees was more than 4000 years old, and he broke the perforator in a moment of excitement.He applied to use a chainsaw to cut logs, but was allowed by the forest inspector.They randomly cut off the trunk 2.5 meters above the root, and then carefully inspected it with a low-magnification magnifying glass. They counted a total of 4844 annual rings on the trunk.One of the oldest thorn-cone pine in the world was destroyed in this way.After the news spread, the whole country was shocked, and the U.S. Forest Service finally made a decision to closely protect the thorn pine.

When scientists were studying the bristle-cone pine, they found that the bristle-cone pine coniferous tree growing in the barren land is particularly sensitive to changes in temperature, and people can infer past rainfall records based on the tree's annual rings.Such data can reveal cycles of climate change and assist in forecasting future climate conditions.This is very important in the dry west and other barren areas.Use a hollow borer to drill into the tree trunk and cut a wooden core with a diameter of 6 mm, which will not endanger the life of the tree. The pattern formed by the wide and narrow annual rings drilled by the scientist is similar to the wood used by the cave dwellers of the prehistoric Indians. The annual ring pattern of the archaeological site is compared to determine the age of the archaeological site.

body clock
The human body has biological clocks with periods of 33 days, 28 days, and 23 days for intelligence, emotion, and physical strength respectively. These three "clocks" have obvious ups and downs, and there are high tide periods, low tide periods, and critical periods in their respective operations.These three "bells" are like a coordinated, graceful and mysterious trio, playing out the movement law of human life.For example, when the three rhythms of the human body are running at their climax, they are full of energy, quick in thinking, optimistic in mood, strong in memory and understanding.The child born at this time must be a smart and eugenic child.During this period, increasing the amount of study and exercise can often get twice the result with half the effort.Students tend to get good grades in exams, writers tend to show "inspiration" sparks, and athletes tend to break records during this period.Zhu Jianhua, a famous Chinese high jumper, broke the world high jump record three times a year. The time was June 3, 3, when he jumped 1983 meters. On September 6, 11, he jumped 2.37 meters. On June 1983, 9, he jumped 22 meters. .These three records were all completed during the climax period of his biological rhythm.Especially the first and third time the record was broken, his stamina clock was just at its peak.

On the contrary, if the trirhythm runs in the critical or low tide period, it will show decreased endurance, depressed mood, unresponsiveness, forgetfulness and distraction. At this time, it is easy to have car accidents and medical accidents, and it is also difficult to get grades in exams. In December 1980, at the 12th Asian Women's Basketball Tournament in Hong Kong, the Chinese women's basketball team and the Korean women's basketball team were relatively close in strength, but our women's basketball team lost to the opponent by 33 points.Afterwards calculation, only one of the 5 main players of the Chinese team is in the high tide period, and some of the other 4 main players have 3 curves in the low tide period or critical period, and some 2 curves in the low tide period or critical period.If the coach was familiar with and mastered the biorhythm of the players on the field and adjusted the "lineup" appropriately-letting the players who were less skilled but whose biorhythm was at its climax, it would not have been so disastrous.The onset of the elderly is often at the low tide of the emotional clock, and the death time of many diseases is just on the double critical day and triple critical day of the three rhythms of intelligence, physical strength and emotion.Knowing the critical day and low tide period of your own tri-rhythm, you can prepare psychologically early, overcome difficulties with tenacious will and a high sense of responsibility, and pass the critical day and low tide period safely.

(End of this chapter)