<h1 class="pgc-h-arrow-right" data-track="2" > headless fly</h1>
There are many magical phenomena in nature, such as: flies can still survive for a long time after screwing their heads off, and even continue to fly, some people have observed this phenomenon and photographed it.
Not only that, but some people have even found that if the head of the fly is cut off, the fly will not die immediately, it can still survive for a long time, and more importantly, in the end, the fly will not die because of a severed head or excessive bleeding, but because there is no head, it cannot eat and starve to death.
Even in idioms, there is a saying of "headless flies", from Feng Deying's novel "Mountain Chrysanthemum", which is now used as a metaphor for chaotic collision without a target direction.
To know the definition of human "death", there is still a lot of controversy in the scientific community. However, in general, "brain death" is considered to be a more reasonable and scientific definition of "death" than "heart death", because scientists have long discovered that after the heart stops beating, the brain will continue to work, but if the brain dies, the function of the whole brain will be permanent, irreversible. Therefore, after a person is also brain dead, it is considered that the person has died.
And flies are completely different from people, after the head is screwed off, it can still survive, it is simply amazing. So what's going on here? This time we will talk about this matter.
<h1 class="pgc-h-arrow-right" data-track="8" > the nervous system of flies</h1>
For humans, the brain is the central nervous system and belongs to the highest part. Once the brain stops working, the person falls into a deep coma, unable to breathe on their own, and self-awareness is lost. Therefore, human beings are highly dependent on the brain, and the basis of all this is that human beings belong to vertebrates, and after the brain gives orders, it can be transmitted to the rhabdomy muscles of the limbs through the spinal tract white matter in the spinal canal for motor regulation, as well as the internal organs of each part. The same sensations of the whole body and the sensations of the internal organs are also transmitted to the brain through the spinal white matter in the spinal canal, which produces sensations.
However, flies and humans are completely different, and flies belong to the phylum Arthropods - Insects - Diptera - Shorthort suborder, not vertebrates, but invertebrates. It has no spine on the dorsal side, and its head is small. This makes the fly not actually adopt the same survival strategy as humans, that is, relying on the "brain" as a nerve center. The nervous system of flies is divided into three main categories:
central nervous system
Sympathetic nervous system
Peripheral nervous system
Among them, the central nervous system is mainly responsible for sensory, contact and motor coordination; the sympathetic nervous system is mainly responsible for controlling the various activities of feeding, breathing, and even internal organs; the peripheral nervous system is mainly responsible for collecting receptor stimulation and transmitting stimulation to the central nervous system, as well as transmitting the response of the central nervous system to the reactor.
Unlike humans, the central nervous system of the fly is actually more than one, but is composed of the brain, the sub-throat ganglia, and the abdominal nerve cord. The brain is responsible for the midline of sensation and connection, and also plays a role in behavioral coordination and inhibition, which is relatively single in function compared to the human brain. The subpharynaryngeal ganglia is responsible for the activity of the mouth organs, to put it bluntly, it is to control eating. The abdominal nerve cord is the nerve center of the body segment. The sympathetic nervous system is divided into oral nerve system, middle nerve and compound nerve system, which control the digestive tract, valve and dorsal blood vessels, hind intestine and reproductive organs respectively. The peripheral nervous system plays a conduction role in the body of the fly.
From here we cannot find that the flies' own nervous systems are not highly concentrated, and that many of their behaviors rely primarily on instinct, which rarely learn later, as humans do.
Not only that, because the head and body are very small, so they are in the process of evolution as far as possible to compress their own nervous system, so that it will not become very complex, many of the structures are the structure of the chain nervous system, and even pain, emotions and so on are abandoned in the evolution.
<h1 class="pgc-h-arrow-right" data-track="18" > what would a fly look like if there were no heads? </h1>
When the fly's head is screwed off, it loses only the corresponding function of the head, but the other parts can still move normally according to the "instinct". One might ask, don't flies die from excessive blood loss?
In fact, the fly uses an open tube circulation, which means that a large amount of blood is in the fly's own body, rather than the blood circulation system like humans. Therefore, it is not possible to die from excessive blood loss. Not only that, but the fly's breathing will not stop because the head is gone, this is because its respiratory system is on both sides of the abdomen, mainly relying on the nervous system of the abdomen, not on the head, so it will not die. Can the fly live without its head?
The fly doesn't mean that it can live forever, it will still die. The main reason is that after being screwed off the head, due to the loss of the ability to eat, you will eventually be starved to death. But then again, flies rarely screw their heads off, presumably by mistake when they try to keep themselves clean.
#苍蝇 #