is so curious, snail 's PP actually grows on the side of his head, and the tentacles he uses as his nose and eyes grow on the edges of his excretion port and vent. Others are not allowed to sleep soundly under the bed, but a snail has to smell the smell of shit while sleeping?
Knowing this information point, I suddenly understood why the snail did not dare to crawl too fast. If the speed of the car was too fast and the wind was too strong, and the BB was dry and stuck in the excretion port in the wind, it would be a tragic story. Of course, this is not the fundamental reason why the snail crawled so slowly.
The reason why the snail crawls slowly is just because it is a mollusk and needs to use the friction of its abdomen to move forward. It is not really afraid of the dryness of the BB on the face.
Let’s get back to the topic, why does the excretion port of a snail grow on the top of its head? Generally, this embarrassing situation must be inseparable from their evolutionary process. In other words, if you want to understand the reason, you must look for the reason from their ancestors.
You must not think that snails are just creatures that appeared as humans evolved . In fact, if you want to trace the ancestors of snails, you can start from 500 million years ago, which is the Cambrian era .
The ancestors of snails were also aboriginal inhabitants of the bottom of the ocean in the early days. After hundreds of millions of years of evolution, they transformed from linear animals into annelids , but they could not escape the fact that they were molluscs. In order to absorb nutrients more conveniently, the snail has evolved nearly 20,000 teeth on its tongue. Such a large number of teeth also makes the snail the animal with the most teeth in the world. In terms of the number of teeth, snails can proudly say: This is passed down from their ancestors.
All the snail's teeth are on the tongue, scientifically known as radula. The rows of teeth allow the ancestors of snails to squirm and ingest food in the soil more conveniently. Of course, animals with radulas are not limited to snails, such as abalone, chitons, or squid.
Snail's radula
But annelids like the ancestors of snails have no bones, are not aggressive, and are not even toxic. For many marine creatures, it is equivalent to a delicious piece of fat meat, the kind that sizzles and emits oil when you bite it.
Therefore, the ancestors of snails worked hard to accumulate calcium absorbed from the sediment outside the body, and protected their soft bodies with hard substances to form an armor. Although this process is very long, at least it effectively gets rid of the dilemma of no longer being a delicious meal.
So how do snails turn the calcium in their bodies into armor? It's interesting to talk about this.
Mantle is a layer of membrane covering the body of molluscs. Under normal circumstances, the mantle has a lubricating effect. It can not only reduce unnecessary friction during the process of peristalsis, but also play a role in moisturizing.
and In the process of evolution, the mantle of the snail can gradually generate electric current, which then separates the calcium ions in the body and accumulates them on the body surface, gradually forming a hard shell. The self-protection mechanism of will form a genetic imprint as it continues to reproduce for hundreds of millions of years, so that its offspring will have a shell to protect themselves when they are born.
As the snails came ashore one after another, they switched from gill breathing to lung breathing. They discovered that the shell that protects themselves actually has a moisturizing function, allowing them to retain water in rainy days and hide in houses or in the mud in hot weather. They can even use this moisturizing little house to hibernate. This little house simply kills two birds with one stone.
After generations of evolution, the snail's shell gradually became more and more perfect, but it faced another embarrassing problem.
The ancestors of snails did not consider the problem of excretion when evolving, so their shells are fully covered and will gradually grow outward in a spiral as the snail's body grows.It is different from hermit crabs in that hermit crabs need to change the size of their shells to protect themselves, while snails only have one house in their lifetime.
Most of the creatures with snails basically have this structure. In order to facilitate excretion, the digestive system is inside the snail, and the excretion port usually extends to the outside of the snail. Otherwise, a large amount of feces will accumulate inside the snail and make the house dirty. Therefore, even if they are as small as snails, they are not willing to excrete their BB in the bed. Therefore, the excretion port of snails will grow with them and always remain outside the shell.
Of course, don’t think that the snail is really so careless and insists on pooping on the top of its head. In fact, it is still a bit careful, that is, the snail has developed its breathing and excretion openings on both sides of its head, so that when breathing, it will not be fumed by smelly farts until it foams at the mouth.
There are more than 525,000 recorded snail species in the world. Currently, the largest snail in the world belongs to the African giant snail. The longest one can reach 20 centimeters. However, although the African giant snail is the largest snail species in the world, it is not edible. Like the apple snail, it is a snail that is harmful to crops. In addition to vegetables, fruits and trees, its diet also includes the corpses and feces of its companions. One can imagine how many bacteria are contained in the BB excreted by such an omnivorous snail.
There once was a 10-year-old boy in Guangzhou. Because there were many large African snails in the greenery of the community after the rain, he played with them. As a result, he was admitted to the hospital soon after being infected with Angiostrongylus cantonensisand.
This disease is a type of meningitis, and its full name is eosinophilic granulocytic cerebrospinal meningitis. The cause of the disease is that this kind of Angiostrongylus invades the central nervous system of the human body, causing illness and even death. Nowadays, many families raise several large snails for their children to cultivate their children's sense of responsibility and emotional intelligence. However, many vendors sell large African snails as pet snails. After all, such a large snail makes people like it.
African giant snail
In our country, the snails that are kept as pets are generally white jade snails, bright large snails, agate snails and other snails with relatively good looks. If you are interested in raising them, you can also take a close look to see if the snail's BB is flowing down from the side of the face.
At present, several kinds of large snails from Europe are widely served on the dining table, especially France.
However, according to the information I have found in recent days, the French snails that people understand do not seem to be the same as the real snails in French cuisine. Some bloggers who have personally experienced snail French cuisine bluntly said that what is placed inside the snail shell is not real snail meat , but minced snail meat mixed with seasonings. It is not whole at all, and there is no way to tell whether the snail meat here is real or fake. Maybe the snail shell is a veteran actor.
