The mystery of animals

The mystery of animals predicting earthquakes

Earthquake is one of the most serious natural disasters. Until today, mankind has not found an effective method to predict earthquakes completely. However, it has been found that many animals often have abnormal reactions before major earthquakes.

1976 The day before the Tangshan earthquake, villagers in Wangdongzhuang, Luannan County, Tangshan area saw big mice running around in the cotton field with little mice biting their tails in turn and following them in a string. At that time, someone said, "When a mouse moves, it dares not move." There is a dog in Yingezhuang, Tangshan City. The night before the earthquake, it just wouldn't let its owner sleep. As soon as the master lay down, he came into the room and shouted, and the master drove him away. He called into the room again and even bit the owner. The master was very angry, picked up a stick and chased him out of the door, and then a big earthquake happened.

In China, using animal anomalies before earthquakes to predict earthquakes has achieved good results. 1967 On the morning of July 18, the keeper of Tianjin People's Park found loach and tortoise tumbling up and down. Swan feet in the air, just don't go into the water; The Siberian tiger is listless and dull; Tibetan yak rolled on the ground. They immediately reported to the Municipal Earthquake Office and put forward their predictions. Results An earthquake of magnitude 7.4 occurred in Bohai Sea that afternoon. So, why do animals have abnormal reactions before earthquakes? As we all know, before the earthquake, the rocks in the source area underwent drastic physical and chemical changes under the strong ground pressure, and at the same time, physical phenomena such as sound (mechanical vibration), light, electricity, magnetism and heat were produced.

The phenomenon of ground sound before the earthquake is a well-known fact. In recent years, experimental research and field observation have found that these sounds are caused by rock fracture in the source area. The sound frequency is not only 200 ~ 20000Hz, but also ultrasonic waves above 20000Hz and infrasound waves below 20 Hz. The human ear is slow to respond to ultrasound and infrasound, but some animals are quite sensitive to them. For example, fish can feel infrasound of 1-20 Hz. Before the earthquake, goldfish panicked, screamed and even jumped out of the fish tank, which may be related to infrasound or ultrasonic waves emitted by the source.

Ground light is also a precursor phenomenon of earthquakes. The dazzling light and rich colors on the ground are likely to excite animals. Birds have developed optic nerve, are good at farsightedness and are particularly afraid of colors they have never seen before. The abnormal reaction of birds was very common before the earthquake, which was probably related to land light.

It is a fact that animals can perceive earthquakes in advance. However, the abnormal reactions of animals are not all caused by earthquakes, but also by weather changes, seasonal changes, changes in living environment, improper feeding, fright or other physiological changes. Therefore, the research on the relationship between animals and earthquakes is still in the exploratory stage. Although some causal links have been discovered, the mystery is far from being fully understood.

Mystery of animal navigation

Many animals in the world have peculiar navigation abilities. For example, the green turtles living in South America set off from the coast of Brazil in groups in mid-June every year, which lasted more than two months and traveled more than 2,000 kilometers to Ascension Island in the Atlantic Ocean, where they gave birth and then returned to their hometown. Two months later, the turtles hatched and swam back to the distant Brazilian coast like their parents.

Birds may be better at this strange voyage. Arctic terns, which are only 4 cm long, nest and lay eggs in New England every year. I flew to the south with my portable children in August, arrived in Antarctica in June 5438+February, and flew back to New England in the following spring, with an annual flight distance of 35,000 kilometers.

Interestingly, many domestic animals closely related to human beings also have the ability to go out for a long distance without getting lost. How do these animals tell the direction and know the route? Scientists' animal navigation experiments with bees and pigeons have initially revealed the secrets of navigation of these two animals. Frish, a famous Nobel Prize winner and Austrian biologist, measured the basic navigation ability of bee peak with a series of experiments in the 1940s, which proved that bees usually use the sun as a compass to navigate, and pointed out that bees used the sun as a reference point to tell other bees how to "dance" to reach the flower source they found.

Through the homing pigeon experiment, it is further proved that animals sail with the sun as a compass. Scientists have done an experiment: keep a group of pigeons in a room 160 km west of home, turn on the lights at noon to simulate dawn, and then release the pigeons. They thought it was dawn and the sun was in the east, but it was only in the south. After seeing the sun, pigeons navigate south according to the sun, and they think it is going home to the east.

Bees and pigeons can not only navigate smoothly when there is sunshine, but also return home accurately on cloudy days without sunshine. Therefore, it can be speculated that they may have another navigation system. Scientists first discovered through experiments that bees are very sensitive to magnetic fields. American scientist Walcott once did an experiment. He put a small helmet on the pigeons, which can precisely control the magnetic field when each pigeon flies. Pigeons can return normally on sunny days, but on cloudy days, the magnetic field generated by the helmet is controlled so that the pigeons cannot fly back. If a magnetic field with the south pole facing upwards is generated, pigeons can fly back directly, which proves that pigeons navigate by using the magnetic north pole.

Scientists' experiments have initially revealed the secrets of the navigation of bees and pigeons, but the positions of the sun and stars will change with time, and even the intensity of the geomagnetic field will change. So how pigeons and bees adjust their navigation behavior according to changes is still unknown. In addition, there are many kinds of animals, and it is a secret how turtles, insects, butterflies and other animals that can sail back to their hometown.

The mystery of animal hibernation

Hibernation is the unique ability of some animals to resist cold and maintain life. When hibernating, they can go without eating or drinking for several months and will not starve to death. The most incredible thing is that the mother bear gave birth while hibernating.

Scientists have been studying the phenomenon of animal hibernation for centuries. They found that there is a layer of white fat under the animal's cortex, which can prevent the body from emitting heat. Brown fat is also distributed around the scapula and sternum of hibernating animals. Like an electric blanket, it produces 20 times as much heat as white fat. The lower the ambient temperature, the faster it produces heat. When the temperature drops, the sensory cells of hibernating animals send messages to the brain to stimulate the sympathetic nerves in brown fat, so that the animal's body temperature is just kept at the level to avoid freezing to death.

Although people have understood the physiological changes of animals, what causes animals to hibernate? About a month before entering hibernation, the black bear ate for 20 hours every 24 hours, and the daily calorie intake increased from 7,000 calories to 20,000 calories, and the weight increased by 100 pounds. It seems that these are controlled by one or more hormones that animals prepare for hibernation, that is, there is a substance in hibernating animals that can induce natural hibernation.

In order to confirm the above speculation, scientists conducted experiments on squirrels. They injected the blood of the hibernating weasel into the vein of the active weasel, and then put the active weasel in the refrigerator at 7℃. A few days later, they went into hibernation. These experiments show the possibility of natural hibernation induced by substances.

Hemorrhagic serum and blood cells were separated from the blood of hibernating animals and injected into two groups of yellow mice respectively. Soon they all hibernated. The filtrate and residue obtained by serum filtration were injected into weasels respectively, and it was found that only the filtrate could cause hibernation. People get enlightenment from this: the substance that induces hibernation is a very small amount of substance in serum. Interestingly, using the serum of hibernating Marmota is the best way to induce Rattus norvegicus to hibernate, which can induce Rattus norvegicus to hibernate in winter or summer.

Therefore, people draw a preliminary conclusion: the formation of hibernation is not only determined by inducers, but also the result of the interaction between inducers and anti-inducers. Animals are making inducers all year round, while anti-inducers are only produced in spring. In autumn and winter, more inducers promote animal hibernation; In spring, there are more anti-inducers, and the inducers are suppressed, and animals wake up from hibernation.

Although some progress has been made in the study of animal hibernation, many mysteries remain unsolved.

The mystery of seasonal migration of animals

Every autumn, flocks of geese line up in neat rows at high altitude and fly to the far south.

The next spring, the geese will fly back exactly the same way. This habit of changing habitats according to different seasons is called seasonal migration. Birds with this habit are called migratory birds.

Like geese and swallows, they are all migratory birds. The migration time and route of migratory birds remain unchanged almost every year. What is even more peculiar is that some migratory birds, such as Jin Siyan, can find the "old house" they lived in a few years ago when they return to their hometown the next year, and live in this "house" for generations.

In addition to migratory birds, some insects also have migratory habits. There is a beautiful butterfly in America, the monarch butterfly, which is called the king of hundreds of butterflies. Every autumn, it flies south from North America in droves, with a journey of more than 3,000 kilometers. They spend the winter in Mexico, Cuba, Bahamas and Southern California, and then gradually migrate northward in the following spring. They breed on the way, lay eggs and die, and the new generation of monarch butterflies in their eggs fly to the south for the winter. It is handed down from generation to generation.

Why do some birds and insects have this migratory ability? In the process of migration, what direction do you rely on? These problems are interesting and difficult to solve. Short-distance flight can be oriented by vision, and long-distance flight is not enough by vision alone.

Scientists speculate that birds may use the position of the sun as a compass. If so, they must compensate for the time difference caused by the movement of the sun. Therefore, scientists believe that migratory birds may have a biological clock that can accurately calculate the movement of the sun and check the time during the day. So how to orient at night? A very reasonable inference is that they use stars to determine their position. But on a starry night, they will still fly as they should. What is the positioning? So some people think that it is possible to use the earth's magnetic field, polarized light, air pressure, smell and so on for orientation.

For the seasonal migration of butterflies, scientists think it may be related to genetic factors. The research on seasonal migration of butterflies has just begun, and scientists are looking forward to more and more interesting discoveries.

The eternal mystery of the mouse

Some rare animals in the world, although people try their best to protect them, are still on the verge of extinction, and some have become extinct. However, some animals, such as rats, can't be destroyed by various methods, and groups of rats are still causing trouble everywhere.

Among all mammals, rats are the most numerous and widely distributed. Although people are constantly killing mice, cats, snakes, weasels, owls and many other natural enemies are constantly threatening them, but all kinds of mice still exist, and some mice are even more and more rampant.

In recent decades, people have poisoned mice with various drugs, and the effect was good at first, but gradually the effect of these drugs became less and less, and even some mice were not afraid of rat poison at all. Scientists have found through experiments that these mice have developed drug resistance, which can be passed on to young mice. The strong adaptability of mice surprised scientists.

What is even more surprising is that rats can effectively deal with nuclear radiation. After World War II, the United States conducted an atomic bomb test on an island in the western Pacific Ocean, and the mushroom cloud continuously emitted deadly rays to the surrounding area. A few years later, biologists found on this island that there were radioactive substances in plants, fish under rocks and soil, but mice were neither disabled nor deformed, and they were particularly fat. Although the mouse's cave can play a certain defensive role against nuclear radiation, it really needs a certain physiological "foundation" to withstand the test of nuclear radiation.

So far, no one has been able to give a complete scientific answer to what strange physiological factors and abilities mice have.