The fearsome ragno violin occasionally comes back in the newspapers to terrorize the whole country. He is described as an aggressive being with a fearsome poison, extremely dangerous. But it really is? As unfortunately it often happens, the reality is very different from what journalists tell.
A violin spider… Help!
In recent days, the terror of the violin spider has spread, powered by the media always on the hunt for sensational news. And what's more sensational than a lethal spider that rages in our Italy? It all started from news that an unfortunate traffic policeman from Terni risked dying from the bite of one of these spiders, it is therefore a dangerous species?
As usual, it all depends: its venom is actually dangerous and therefore care must be taken if you encounter one of these animals, but we must also keep in mind that all spiders always bite in defense and do not go looking for people to afflict. They actually have no interest in biting us, because obviously we are too big prey for them. Rather, biting for defense is a waste of energy for the spider, because he will be forced to wait for the production of more poison to be able to hunt. The first reaction to the disturbance is flight, the bite occurs only as a last resort, for example if the spider is crushed inside a shoe, between one foot and the inner sole.
Arachnids, not insects!
I ragni vengono spesso definiti insetti, ma in realtà non lo sono affatto. Aracnidi e insetti sono imparentati tra loro come potrebbero esserlo uccelli e mammiferi: fratelli, ma non gemelli.
Il modo migliore per distinguere un ragno da un insetto è contare il numero di zampe: gli insetti ne hanno sempre sei, mentre i ragni (e gli aracnidi in generale) ne hanno sempre otto. Gli arti però sono ben dodici, infatti sono zampe vere e prorie gli arti dal terzo fino al sesto paio.
Il secondo paio di arti si è evoluto in un sistema sensoriale, che ha più o meno la stessa funzione delle antenne per gli insetti. Questi arti, chiamati pedipalpi (figura 2), sono anche utilizzati dai maschi durante l’accoppiamento.
Il primo paio invece, essendo vicinissimo alla bocca, si è evoluto in una struttura di supporto alla predazione. Il veleno del ragno infatti si trova all’interno di questi due arti chiamati cheliceri, che terminano ciascuno con una “zanna” che in realtà è un artiglio modificato e che serve a inoculare il veleno. Per questo è improprio dire che “pungono”, infatti i ragni “mordono”.
Un’altra differenza molto ben evidente tra ragni e insetti è la suddivisione del corpo: gli insetti hanno sempre il corpo suddiviso in tre sezioni (capo, torace e addome), mentre i ragni hanno solo due sezioni (cefalotorace e addome). In addition, at the extremity of the abdomen there are the sericogenic glands that allow spiders to weave their famous and spectacular webs.
The violin spider
The common name “violin spider” indicates the entire genre Luxosceles, which includes a hundred species scattered all over the world. They are called this because of the characteristic violin-shaped spot they have on the back of the cephalothorax, which, however, is not always visible. The surest way to attribute a spider to the genus Luxosceles is to observe their eyes: violin spiders in fact always have six eyes, distributed in 3 pairs equally spaced around the front of the cephalothorax.
One of these species, Luxosceles rufescens From the oven, 1820, it is typical of the Mediterranean environment and is also very common in Italy.
L. rufescens it is a relatively small spider, in fact, females can reach 2 length centimeters (legs included). The abdomen is oval in shape and devoid of particular ornamentation, while the legs are long and thin. The whole body is covered with small bristles that have a sensory function.
It is an animal that only goes out hunting after sunset, spending his days as a refugee under stones or in any case in quiet caves. It tends to be siantropic, that is, to live in man-made environments because the mild climate of our homes is exactly what he does for him. Precisely because he is shy, in homes he prefers to take refuge in quiet and dark corners, as in wall units or attics. It may happen that it gets inside shoes or sheets, so it's always good to take a peek before going to bed or wearing a shoe.
The venom of the violin spider is cytotoxic and in fact it would be better to avoid getting bitten. This poison destroys cells in a fairly large area around the bite, causing a large necrotic lesion that takes weeks to heal and can easily become infected, worsening the clinical picture. More rarely, the poison can attack the blood and cause systemic effects such as the destruction of red blood cells and forms of renal failure, all accompanied by rashes similar to exanthematous diseases such as measles.
It must be said, however, that the poison of ours Luxosceles rufescens it is definitely less powerful than the American Luxosceles recluse, for which deaths are documented. However, there is not even a confirmed case of death caused by a European violin spider, despite being incredibly common on a continent like the Europe they live in 500 million of people. It is not impossible that this spider killed and perhaps a case of this type occurred in 2016 in Italy, but it is evidently such a rare phenomenon as to be statistically insignificant, in the sense that it escapes any detection.
In conclusion, therefore, we can say that the violin spider is an animal to be careful of and that should never be handled, under any circumstances. Being bitten is not pleasant and if it happens it is important to contact the health authorities as soon as possible, because there is a risk to life, albeit remote. However, the reputation as a killer monster that the media have sewn upon it seems completely unjustified: it is just an animal that defends itself as any of us cornered would. Let's respect him and he will respect us.
- The luxuriescelism, on the English Wikipedia