Wild soybeans in the plant world are often used by scientists to conduct various experiments because of their high reproductive efficiency; in the animal world, leech (common name leech) is definitely a star experimental species, due to its blood-sucking and resistance. The characteristics of blood clotting have been widely used in the medical field. Recently, scientists have used blood-sucking leeches as a new tool to determine the distribution of wild animals in the area by detecting the blood DNA of the animals they suck in their bodies. Today we will re-understand this magical creature. Only by understanding it can we not talk about it and learn to get along with it correctly.
Amphibious and hermaphrodite
leeches are found in forests, oceans, lakes, ponds, and paddy fields in most parts of China. There are more than 100 species in our country, and leeches in the north can also hibernate. Although they are very similar to earthworms and belong to the class and the class Annulus , leeches have no hair on their bodies and their bodies are stronger than those of earthworms. There are 10 eyes, you read that right, 10, arranged in a ∩ shape on the front of the body.
The biggest feature of leeches is that there is a sucker on the head and tail, and the sucker on the tail is larger than the one on the head. There are three semicircular jaws in the mouth of the head forming a Y shape. When attached to the animal's body, the jaws are used to drill into the skin. When walking, it looks like a ruler, moving forward in a telescopic semicircle.
Leeches are hermaphroditic, heterosexual mating, internal fertilization, and have both male and female reproductive organs. During mating, they proceed in opposite directions. There is a "sex reversal" phenomenon in the life history, and there is an exchange of gender roles. A leech can be both a father and a mother. , playing different roles at different times in life. About one month after mating, the female's genitals secrete thin mucus, and the egg belt is wrapped in the middle, which is shaped like a "cocoon". It is excreted from the body and hatches in wet mud at a suitable temperature. It takes about 16-25 days to hatch from the cocoon. The young leech begins an independent life.
It does not hurt to suck blood, but it is difficult to stop bleeding.
When most people think of leeches, they usually think of their blood-sucking properties, but you really blame them. In fact, leeches are carnivorous animals. Most members of the leech family rely on preying on small invertebrates. A small number of them live as temporary parasites, relying on sucking the body fluids of their hosts. Very few leeches feed on the blood of mammals. How do leeches suck blood? Leeches are usually divided into: snouted leeches and snouted leeches. There is a muscular mouthpart in the pharynx of the leech, also called the snout. The snout can extend from the leech's mouth and then penetrate into the host's body to suck blood. Kissless leeches use their jaws to cut open the host's skin to suck blood.
The amount of blood sucked by leeches is very large. Generally speaking, the amount of blood sucked by leeches can reach 2-10 times of its own body weight at one time. Blood-sucking leeches often go unnoticed by their hosts when sucking the blood of mammals. This phenomenon once led scientists to believe that it would release anesthetics when sucking blood. However, tests did not find any anesthetic ingredients in the leech's saliva. Therefore, the current view is that people cannot easily detect it because the skin on the legs is not sensitive. The friction between the upper trousers and the skin distracts the attention, and it may also be the environment, water temperature and water pressure that cause the leech to cut or pierce the skin without obvious pain.
Once bitten, it is difficult to stop the bleeding! This is because leeches release hirudin during the blood sucking process. Hirudin is the most effective natural anticoagulant known. This is why leeches are often used in medicine to treat coagulation and thrombus . However, leech bites are superficial bleeding, so you can apply appropriate pressure to stop the bleeding. You can also use gauze to stop the bleeding. It should be noted that you must apply iodophor or alcohol disinfection to the area where the leech is absorbed and bitten to prevent Infect. If the leech is attached to your skin, do not remove it violently. Leeches mainly rely on the suction cups in their mouths to be adsorbed under the human skin, so once the suction cups remain in the skin, they can easily cause infection. You can use water or salt, alcohol and vinegar to rinse it off.
Leech doctors have been around since ancient times.
As early as 1500 AD, the Egyptians pioneered leech bloodletting therapy. By the beginning of the 20th century, Europeans were more superstitious that leeches could suck out diseased blood from the human body. They used leeches to treat headaches, brain fever, and fever. Blood sucking treatment.Later, with the development of medicine, this superstitious treatment method was gradually abandoned.
In China, leeches have been used as medicine for about a thousand years, dating back to more than 2,000 years ago. During the Eastern Han Dynasty, the medical sage Zhang Zhongjing used leeches to treat "blood stasis" and "water knots", showing its unique curative effect. It is said that it "mainly expels bad blood, blood stasis, closed menstruation, breaks blood and eliminates accumulation..." Li Shizhen, a miracle doctor in the Ming Dynasty , also believed that dried leeches have the functions of dredging blood, stimulating menstruation, eliminating accumulation and knots, reducing swelling and detoxification.
Today, plastic surgeons use leeches to eliminate blood stasis in vascular occlusion areas after surgery and reduce the occurrence of necrosis. When doctors replant or transplant fingers, toes, ears, and noses, they use leeches to suck blood, which can make the veins unobstructed and greatly improve the success rate of the operation.
Hirudin is composed of 65 amino acids. There are 17 kinds of amino acids that have been extracted, most of which are essential amino acids for the human body. Therefore, the artificial breeding and breeding leech industry at home and abroad has developed a variety of biological products.
Be careful when drinking raw water, it can be parasitic in the body
It is said that in some tropical countries, there was a punishment specially imposed in summer, which was to strip people naked and put them in a pond full of leeches, and soak them for three days and three nights. If the punished person does not die, then the previous grudges can be wiped out. However, only a handful of people can actually survive it, which shows how terrifying leeches can be. So the question is, if a leech is accidentally eaten, can it still survive in the human stomach?
The vast majority of blood-sucking leeches actually temporarily parasitize on the surface of the host rather than in the host's body. Not only that, leeches need oxygen to survive, and they generally exchange oxygen through their body surfaces. Therefore, most leeches cannot survive in an oxygen-free environment for a long time.
However, everything has exceptions. In the large family of leeches, there is a type of parasitic leech. They mainly live in mountain streams and springs. They are very small and difficult to see clearly with the naked eye. If you drink the water from these mountain streams by mistake, the parasitic leeches in the water may infest the human body. In addition to parasitic leeches, some leeches living in fresh water may also enter the human body. They mainly parasitize in the nasal cavity, and sometimes crawl to the host's trachea and throat. There are even cases of crawling to the lungs and causing the host to suffocate.
Many cases of leeches parasitizing the human body have also been recorded at home and abroad. No matter where they are parasitic, these parasitic leeches are sucking the blood of the host.
There have been no cases of leeches entering the human gastrointestinal tract. Therefore, we cannot judge whether leeches can survive in the gastrointestinal tract. However, there is almost no oxygen in the gastrointestinal tract, so even if it is really parasitic in the gastrointestinal tract, it is difficult to live for a long time. Due to the existence of parasitic leeches, there is a certain probability that they will parasitize the human body, but they are only in semi-open parts, such as the nose, throat and other parts. This also tells us a very important common sense in the wild: do not bathe or wash your face in wild streams at will, let alone drink the stream water directly. If you really want to drink it, boil it before drinking it. Yang Aileen/text
