Geographic cone: the most dangerous snail in the world. Egypt - deadly shells Sea cones

26.10.2019

Cone snails have inspired people for centuries. Communities living near the ocean often exchanged their beautiful shells for money and added them to jewelry. Some artists, including Rembrandt, captured them in sketches and paintings. Recently, scientists at the US National Institute of Standards and Technology (NIST) found these deadly predators also fascinating, as they will help them find new ways to treat long-known medical diseases using snail venom as a base.

"It's the same poison that was used to kill the dinosaurs in the movie Jurassic Park," says NIST biochemist Frank Marie. "It's scary stuff, but its power in real life can be put to good use."

Like most NIST researchers, Marie puts everything to the test. Namely, when working with marine animals, he studies RNA and proteins associated with it. As modern technology has advanced, he and his colleagues have become better at analyzing, studying, and catalyzing molecules, working with some of the ocean's little-studied creatures, including cone snails. In 2017, the staff of his laboratory made several significant discoveries about the components of their poison, ultimately these discoveries can lead to new drugs designed to treat serious diseases. As these small calm creatures inject poison, scientists can also safely obtain excellent medicines.

Every day, Marie walks the rows of huge aquarium tanks at Hollings Marine Laboratory in Charleston, South Carolina, checking on the 60 cone snails that have been living in his lab for the past 15 years. Weekly, he and his colleagues engage in delicate negotiations to trade dead fish for a dose of poison to be piped into a tube for further scientific research.

“Cone snails are so unusual. They really don't look like any living thing on the planet, and working on them is almost as weird as working with aliens, but it's also fun. The cone system is like a candy store,” says Marie.

Over 800 species of cone snails have been found worldwide, mostly in the hotter tropical regions. They are hermits, faceless creatures and are not at all aggressive, but will be capable of defense if they are picked up by the next shell collector. The smallest snails have a sting that is about as strong as a bee sting, but the sting of larger species can kill an adult human in a matter of hours. The most deadly cone snail is considered to be the "cigarette snail" of the Indo-Pacific region, a snail with a human thumb can inject a toxin so powerful that you only have time to smoke one cigarette and then die from the effects of poison.

Despite the fact that his collection consists of several species, Marie pays special attention to the purple cone snail (lat. Conus purpurascens). This snail is mainly found off the coast of the Eastern Pacific Ocean from the Gulf of California down to Peru and around the shelf of the Galapagos Islands. It slowly moves along the rocky bottom, where it grows up to several centimeters in length. All snails of the genus Conus are nocturnal but can often be seen on beaches.

A photo. The snail expands its proboscis and releases venom into a latex tube.

Despite their slow movements, these snails have evolved to be able to attack much more mobile creatures in the dark, releasing one harpoon tooth at other fish, snails and worms. After the poison is injected, the victim is instantly immobilized and unable to hide. The snail then slowly draws the immobilized prey into its shell to digest it whole. After use, each tooth is discarded and immediately replaced by another. Some types of cone snails have 20 or so similar teeth ready to be used when the next potential prey swims by.

In its usual form, the poison of the cone snail will obviously not be an excellent cure for human ailments. But by unpacking it piece by piece and studying each component at the molecular level, Marie and his colleagues want to study and describe how each component of this toxin performs its function.

“We learn a lot about them,” says Marie.

For example, is the poison of a cone really capable of instantly appearing in the nervous system of another animal? And how does it paralyze the victim so effectively? Even more puzzling is that some individual purple cone snails are not poisonous at all, which Marie believes may be due to the developmental stages of these snails.

The clues about cone snails can be used to develop advanced drugs that move faster and much more efficiently through the patient's body, such as new types of insulin to cure diabetes or improve the cure for certain neurological diseases, such as Alzheimer's disease. New discoveries of venom components may provide us with new drug delivery systems that will be aimed at reducing the development of rapidly progressive cancers. Some scientists plan to use the components of the poison to get rid of drug addiction. Even today, one of the components of cone snail venom is used in anti-wrinkle creams, using inflammation under the skin to bulge wrinkles and fine lines on people's faces.

Prior to writing a paper published in the Journal of Proteomics (1), Marie and colleagues used cone snails as probes at the molecular level to detect important overlap between the human central nervous and immune systems. Their study shows for the first time that this classic toxin, which normally targets the central nervous system, can also have a direct effect on the immune system. It has been found that once certain types of cone snail peptides, known as conotoxins, enter the body, certain living cells signal in a certain way. These new advances could help us develop new treatments for breast, stomach, and lung cancers, as well as improve the treatment of tuberculosis, since all of these diseases cause certain cells to multiply. In order to apply the toxin as a real drug, this study provided a roadmap for better understanding the growth process of unwanted cells.

In another study recently published in the Journal of Proteomics (2), Marie and colleagues worked on isolating an enzyme from the cone snail venom called Conohyal-P1. They resorted to mass spectrometry using an ultra-high resolution spectrometer, which is one of the most powerful tools for counting and identifying proteins in a sample. A similar enzyme has been found in both lionfish venom and bee venom. Unusually, it is also present in the semen of many mammalian species as it helps to relax the cell walls of the ovaries and thus facilitate sperm delivery and successful reproduction.

"We knew that this enzyme could destroy extracellular tissue," says Marie, speaking of the outer membrane of cells. “But today we were able to carefully analyze the activity of this enzyme in order to use it in future research. Also, we have identified a new subtype that was previously unknown.”

In a third publication, published recently in the journal Neuropharmacology (3), Marie and colleagues analyzed cone venom toxins by testing the central nervous system response of fruit flies. Although fruit flies are largely different from humans, their central nervous system can be a good model for a variety of medical tests because the basic structure of fruit fly brain cells is similar in structure to human brain cells. So if a fly's brain cells respond in one direction, scientists know that human cells will respond in the same way.

A video that tells about the danger of a cone snail for a person, its ability to kill a person from one prick with a poisonous tooth

Marie's team specifically wanted to know how conotoxins interact at the molecular level with various targets in their victim's nervous system. The poison of the purple cone snail is saturated with a large number of blocks of such proteins, there are more than 2000 of them.

“Poison is incredibly complex. We wanted to get an answer to this question: what components of it can be used for medical purposes,” says Marie.

In this particular case, they found that the flies' response to doses of cone snail venom primarily took place in receptors that control muscle movement and addiction. These factors can be taken into account when creating advanced drugs for Parkinson's disease, in which the human musculoskeletal system is often disturbed, the ability of a person to control basic body movements is impaired. It can also help develop effective methods for getting rid of nicotine addiction.

“The pattern on the cone shell is very beautiful. But I believe that biochemistry and biology are even more amazing, and by understanding the various facets of the toxin, we can open new doors in the field of medical use. In the end, we will be able to crack the code,” says Marie.

Recent cases of snail cone attacks
A tourism worker has been stung by a cone snail in Australia's Whitsunday archipelago.

In North Queensland, a crew member on a tour boat was stung by a cone snail, causing his respiratory system to malfunction.

At noon on Tuesday, June 9, 2015, a 25-year-old man was walking barefoot in the shallow water near Whitehaven Beach when a cone snail stabbed its harpoon into his skin.

Given the tide, it was only a small window for the man to be taken to the hospital. The pilot managed to land on a narrow strip of sand and the patient was transported by helicopter in an inflatable boat.

"If we had any delay in the helicopter, we would have to rethink our strategy, spend valuable time on this process," said a spokesman for the medical service.

The man was taken to McKay Hospital, where he remained in stable condition. In severe cases, in addition to pain, cone snail venom can cause muscle paralysis, blurred vision, respiratory failure, and death.

Few people know that over the past 90 years, 36 people have died because of a lowly killer, said University of Queensland chemistry professor David Kraik.

The cone snail has a proboscis that hangs like a bait to attract fish. At the end of the proboscis there is a hollow tooth through which poison is injected.

Regarding this particular case, Dr. Craik said that the poison blocked his nerve impulses that control the muscles associated with breathing.

"The lethal dose of venom for a 70-kilogram adult can be as low as 2 mg, so comparable toxicity is comparable to some snakes," he said.

Links to studies:
1. dx.doi.org/10.1038/s41598-017-11586-2
2. dx.doi.org/10.1016/j.jprot.2017.05.002
3. dx.doi.org/10.1016/j.neuropharm.2017.09.020

Deadly snail cone

Coral reefs, stretching along the entire coast of Australia, are of enchanting beauty; people from all over the world come to see them. But it is here that many vacationers, especially those who are fond of scuba diving, are in danger. Many people know that many fish, such as sharks or warthogs, are bloodthirsty or poisonous. We have also heard about jellyfish that leave serious burns. But not many people know that among snails - it would seem that the most peaceful creatures in the world - there are species that are truly dangerous to humans. The main danger is represented by cone snails, which got their name for the almost regular conical shape of the shell. These mollusks are endowed by nature with a weapon that resembles a harpoon gun in action. Together with the impact of a small thorn, the victim receives a solid dose of poison, which is also fatal to humans.

In total, this predatory family has 400 (according to other sources - more than 550) species that live in tropical seas. There are more of these mollusks on the Great Barrier Reef in Australia than anywhere else.

Killer Cone Snails

conus geographus attaches a fish

Cone snails are predators, and I must say that they are quite successful hunters. During the day, snails hide in corals, and at nightfall they crawl out of their hiding place. They have a highly developed sense of smell. From a great distance, they feel the slightest chemical impurities in the water and slowly follow the trail of their prey. It could be a worm, another snail, or even a fish.

Despite the fact that the latter swims quickly in the water, this does not bother the slow cone snail: its weapon will not let you down.

Sometimes they wait for their prey by burrowing into the sand and luring it with the help of bait outgrowths located along the edge of the head. Some species can stretch their "head", which takes the form of a funnel up to 10 centimeters in diameter.

conus geographus

When the cone approaches the victim at a sufficient distance, he throws his "harpoon" into it, at the end of which there is a poisonous tooth. All poisonous teeth are located on the radula of the mollusk (the apparatus used to scrape and grind food) and, when prey is found, one of them moves out of the throat. Then it goes to the beginning of the proboscis and is clamped at its end. And then, holding this kind of harpoon at the ready, the cone shoots it at the victim. As a result, she receives a decent dose of the strongest toxin that has a paralytic effect.

Small fish are swallowed by mollusks immediately, and large ones are stretched like a stocking.

The following subspecies of snails are considered the most poisonous: geographic cone (Conus geographus), brocade cone, tulip cone, marble cone and pearl cone.

So, what is terrible about this mollusk. Their stigma has a modified goiter that acts like a dart or spear. This "dart" is wetted with a potent poison. This is why even a large, fast-swimming fish will not be able to swim far after the spike hits a target at a distance of more than a meter. This venom is similar to that of the blue-ringed octopus.

For a person, the poison of cones can cause a lot of trouble. Snails strike with a sharp spike that ends in a curved prong, like a harpoon. The injection is very painful, immediately there is numbness of the lesion, nausea, severe dizziness. If timely assistance is not provided, after half an hour paralysis of the respiratory organs and the cardiovascular system may occur.

According to statistics, every third victim of this mollusk dies. This is not because modern medicine is powerless against the poison of the cones. Since the injection takes place underwater, there is very little time to get to the shore, and then to get to the nearest hospital. Even more dangerous are those cases when the victim is alone under water. Since there is a rapid numbness of the injection site, and the pain is such that you can even lose consciousness, a person may simply not swim to the surface on his own.

True, it should be noted that, basically, all cases occur through the fault of the person himself. Attracted by the beauty of the shell, the diver tries to pick up the snail and thus forces the cone to defend itself.


	Length: up to 50 cm The weight: up to 2 kg Habitat: tropical seas. Danger! Together with the impact of a small thorn, the victim receives a solid dose of poison, which is also fatal to humans. The venom is similar in potency to that of the blue-ringed octopus.

Cones are nocturnal predators, hiding in the sand during the day. The radula of the cones has teeth modified for a harpoon - the pointed ends are equipped with sharp spikes directed backwards.

Inside the harpoon there is a cavity connected to the poisonous gland. The teeth sit in two rows, one tooth on each side of the radula plate. When the cone, with the help of the sense organ - osphradia, detects prey, one radula tooth comes out of the pharynx, its cavity is filled with the secret of the poisonous gland, the trunk passes and is clamped at the end of this trunk. Having approached at a sufficient distance, the snail shoots a harpoon and a strong toxin with a paralytic effect is poured into the victim. Some types of cones have bait outgrowths with which they lure fish. Small fish are paralyzed almost instantly and although they continue to twitch, however, purposeful movements that can help the fish escape are no longer observed. After all, if the victim could jerk sharply once, she would have escaped and then the slow mollusk would hardly have been able to find and eat her. They swallow small fish whole, and put on large specimens like a stocking. For a person, such a “bite” can also become dangerous. The geographic cone (Conus geographus) is especially dangerous for humans. Moreover, according to Australian expert Rob Bredl, death can occur within a couple of minutes. In the Pacific Ocean, 2-3 people die from cone bites every year, and only one person from sharks. According to statistics, one out of three or even two cases of a cone stab ends in death. Most often, attracted by the beauty of the shell, a person tried to pick it up and forced the cone to defend itself.

In 1993, there were 16 cone-bite deaths worldwide, of which 12 were conus geographus. Two deaths from C.textile. In addition, dangerous C. aulicus, C. marmoreus, C. omaria, C. striatus and C.tulipa. As a general rule, those snails that prey on fish should be considered the most dangerous.

conus geographus- the most dangerous snail in the world while hunting

conus amadis

poison cones

The venom of cones has recently become of great interest to scientists because of a number of features: this venom consists of relatively simple biochemical components - conotoxins (Conotoxins) - peptides that are easy to reproduce in the laboratory. Snails have a very large variation in toxicity and composition of the poison. Two identical snails from the same location can have very different poisons. This is not observed in other animals - two identical snakes or two identical scorpions have exactly the same poisons. Another feature of the toxins that make up the poison of the cone is the speed of action. Although conotoxins are neurotoxins, they have different peptides in terms of the mechanism of action - one toxin immobilizes, another anesthetizes, etc. This can be very useful in medicine. In addition, these peptides do not cause allergies in humans.

There is no antidote for cone venom and treatment can only be symptomatic. The local inhabitants of the Pacific Islands, when bitten by a cone, immediately incise the bite and bleed.

medical application

Poison cone ( conus magus) is used as an anesthetic (analgesic). For example, the drug Ziconotid is a synthetic form of a non-opioid analgesic, one of the peptides of the cone, the effect of which is superior to all drugs known to medicine. This poison is supposed to replace the addictive morphine.

Scientists have found that the poison of some of these creatures, such as the cone magician ( conus magus), works great as a pain reliever. In this case, the effect of habituation does not occur. As a result, the poison can replace morphine, which is a thousand times more effective. The analgesic drug ziconotide is isolated from cone toxins. Other components of the poison are being tested as a means of combating Alzheimer's, Parkinson's and epilepsy. www.molomo.ru

Cones, along with cowrie shells, are highly prized by collectors. Cone Gloriamaris (Conus gloriamaris), called the "Glory of the Seas", is considered the most beautiful shell in the world. Described as early as 1777 until 1950, only about two dozen of these shells were known, and therefore they could cost up to several thousand dollars. Now the habitats of these snails have been found and their price has fallen sharply.

Cones:
mortal danger or imaginary threat?
Yu.I. Kantor,
Doctor of Biological Sciences
Institute of Problems of Ecology and Evolution named after A.N.Severtsov RAS

Cones ( Conus), perhaps the most species-rich (more than 550 species are already known and at least a dozen new ones are described annually) genus of marine animals from the class of gastropods, or snails. Currently, dozens of scientists are engaged in their study, and different specialties. Collectors are also not indifferent to these snails, since the shells of many cones are incredibly beautiful. Some species have received very poetic names: for example, Glory of the Seas ( C.gloriamaris) or Glory to India ( C.milneedwardsi). Although in our time the number of caught specimens of these “rarities” is in the hundreds, nevertheless, cones traditionally remain the dream of many collectors.

This excitement is skillfully supported in the press, which allows you to keep high prices. However, modern prices for even the rarest cones are nothing compared to those that were, say, at the end of the 18th century. So at the Lionet auction in 1796, two paintings by Franz Hals were put up for sale, the famous painting by Vermeer of Delft "Woman in Blue Reading a Letter" (now located in the Royal Museum of Amsterdam) and ... a five-centimeter sink C.cedonulli(translated from Latin, the specific name of the cone sounds promising - incomparable). Hals went for nothing, Vermeer was sold for 43 guilders, and the cone for 273! However, a lot has been written about the collection merits of cone shells, but information about the biology of the mollusks themselves rarely seeps into popular science literature. Meanwhile, it is not only interesting, but even important from a practical point of view, primarily for divers.

Cones, with their numerous relatives, belong to the family of gila-toothed ( Toxoglossa) or, as it is recently called, conid ( Conidae). These mollusks are distributed throughout the World Ocean, from the water's edge to the maximum depths. They are more diverse and numerous in the tropics, especially in the Indo-Pacific region. Species belonging directly to the cone genus live mainly in the tropics, and only a few of them penetrate the subtropics (one species is found in the Mediterranean). The real kingdom of cones is on coral reefs. Here their number can reach 60 specimens per square meter. A few years ago I worked on the reefs of New Guinea as part of a motley international team of biologists. In just two weeks, on one tiny island that could be walked around in half an hour, we collected shells from 36 types of cones. Of course, in our time this is a record, but it can be used to judge the diversity of cones in the tropics.

Most of the gila-tooths studied have a well-developed venom gland in the form of a very long and twisted tube. The composition and action of the poison have so far been studied only for a very small number of species, mainly for cones. The gland is located inside the teeth, lining in rows a long, flexible membrane plate (radula) - the main organ for obtaining food. Radula can, like a grater or brush, scrape algae from hard surfaces. In predatory snails, the teeth have reached such large sizes that with their help they are able, like wire cutters, to tear off pieces of food. In addition, they have a long and movable trunk, on top of which there is a mouth. In cones and their close relatives, the teeth of the radula are modified, turned into hollow harpoon-shaped needles with holes at the top and bottom. They are easily detached from the membrane. The cones clamp a separate needle in the mouth, and then, by contracting the walls of the trunk, they forcefully inject poison through its cavity into the body of the victim. The notches at the end of the needle are firmly stuck in the body of the victim, and the cone can hold it firmly. The size of the teeth can be very impressive - up to several millimeters, with the longest in cones that feed on mollusks, and the shortest in those that feed on worms.

Fragments of the radula of predatory gastropods.
Left- a section of a long flexible plate 0.9 mm wide,

seated with identical transverse rows of trumpeter's teeth.
On right- a single tooth about 0.4 mm long
cone feeding on marine worms.

Photomicrographs of the author

The fact that cones are poisonous has long been known. Perhaps no other group of marine mollusks has been given so much attention in the popular literature and so many inaccuracies, or even just mistakes, have been made. These snails have not only found their way into all diving guides, monographs on poisonous marine animals and textbooks on toxicology, but also in popular books and magazines, the pages of which often abound with terrible descriptions of a prick (or bite, depending on the author’s imagination), details of agony and of death. I want to make a reservation right away that most of these stories are copied from one book to another and have no basis for themselves. However, the cones are indeed poisonous, sometimes even deadly.

The first case of a person being stabbed with a cone was described at the beginning of the 17th century. Danish naturalist Rumphius, who spent many years on Ambon Island in the Sunda Archipelago (modern Indonesia). Rumphius observed a native who cut his hand with a knife. In response to a naturalist's question, he explained that he had been bitten by a cone and if a lot of blood was not immediately released, then death was inevitable. Rumphius described this dangerous mollusk, it turned out to be a geographical cone ( C.geographus).

The geographic cone is the most dangerous for humans.
Hereinafter, the photo of O.V. Savinkina

However, the biology and behavior of cones remained practically unknown until the middle of the 20th century, when the American scientist A. Cohn took up them. For almost half a century, he has been studying in detail the behavior and nutrition of various types of cones, and thanks to his work it turned out that most of them feed on marine worms, about 50 species (which include the mentioned geographical cone) - fish, and several species, including textile cone ( C.textile) , - other snails.

The poison of cones, especially fish-eating ones, is extremely toxic: the fish is paralyzed a second after the injection inflicted by the harpoon tooth. The mollusk swallows the immobilized fish whole and digests it rather quickly. However, it is not so easy for a slowly crawling snail to catch up with fish, so many cones hunt from ambush, burrowing into the sand. A special organ of smell (osphradium) helps them to feel the fish - a kind of nose, although it looks more like a comb and is located not at all on the head, but in the mantle cavity at the base of the gills. When a fish swims nearby, the cone instantly exposes a trunk with a tooth clamped at the end from the sand and inflicts a fatal injection. Some species, such as the purple cone ( C.purpurascens), lure the fish with the movement of the trunk, imitating the worm in shape and color. In another species, long tentacles grow along the edge of the funnel-shaped head. When such a cone burrows into the ground, only the head remains on the surface, very reminiscent of sea anemones. It can be assumed that in this way the cone lures clown fish ( Amphiprion) that live among the tentacles of anemones that protect them from enemies.

The geographic cone also feeds in a very peculiar way. Its head, stretching, turns into a huge (more than 10 cm in diameter) funnel - a kind of net into which small fish come across. Once inside the funnel, the fish suddenly falls into prostration, then the cone inflicts a lethal injection.

Features of the biology and behavior of the geographic cone attracted the attention of toxicologists. The first who managed to isolate and investigate the poison was an American of Filipino origin B. Oliver from the University of Utah. It turned out that the action of the poison of the cone is similar to the poison of the cobra (but more toxic than it) - it blocks nerve synapses, i.e. interrupts the transmission of a signal from the nerve to the muscle, as a result of which numbness and cardiac arrest quickly develop. Cone venom is a mixture of a large number (up to 50) of low molecular weight peptides containing 10-30 amino acids. It turned out that the composition of conotoxins (their name emphasizes their origin) can quickly change depending on the diet of the snail.

Subsequently, conotoxins were synthesized. When they began to conduct experimental tests of individual peptides on laboratory mice, it turned out to be absolutely miracles: some peptides lead animals to death (this group is called “hook and line”, because poisons almost instantly kill fish, as if they were hooked on a hook), others they only put them to sleep (the “nirvana” group; from them, the fish falls into a stupor, once inside the funnel). There are peptides that cause seizures in mice, while others, on the contrary, prevent them; some - provoke strange behavior, such as climbing vertical walls, jumping, twitching the hind limbs, etc. Conotoxin “King Kong” (these biologists have a funny sense of humor!) Has no effect on mice, but mollusks react very strangely to it - they “creep out” from their own shells so that it would be more convenient for the mollusc-eating cone to swallow them. At least that's what Oliver thinks. Isn't it true, it smells of fantasy here, like in G. Kutner, in which one of the heroes could make the raccoons not only come out of the forest, but also skin themselves.

Any neurotoxins are of great interest to neurobiologists and pharmacologists (everyone knows about the beneficial effect of snake and bee venom on the lower back, which has suffered from sciatica). And cone toxins are no exception.

A fundamentally new drug against epileptic seizures, which is an individual conotoxin, has already appeared among medical preparations. Now in development is the latest painkiller, which has no analogues. It is similar in action to morphine, but is not addictive and works in very small doses. Olivera told me that the patent for this painkiller was bought by a pharmaceutical company for an astronomical sum of $720 million! (I think that one such patent would pay off all the costs of researching not only cones, but also mollusks in general.) We still do not know what amazing discoveries are possible in the future ...

Finally, it's time to answer the question posed in the title of the article. How dangerous are the cones for a person and what to do with a bite. Should upset (and maybe still please) lovers of horror books. Over the entire almost 300-year history, 150 cases of cone bites are described in the literature (in fact, their number is still several times higher), 36 bitten people died. All deaths were caused by a single species - geographic cone. I note that the mortality rate from injections of a mollusk of this species reaches 70%, it is really dangerous for humans. Since the poison of the cones consists of many individual peptides, there can be no antidote for it. Apparently, the only way to survive the bitten - profuse bloodletting. And in this respect we have not advanced at all in comparison with the savage whom Rumphius observed almost 300 years ago. It seems that the geographic cone is much more aggressive than other species, since it “bites”, not only hunting, but also defending itself. Other fish-eating cones are also quite dangerous, as well as textile cones that feed on mollusks.

The textile cone feeds on other types of snails. Very active, in the process of hunting it can inflict up to eight injections in a row, and for each injection a separate tooth is used, which gets stuck in the body of the victim. It happens that it “attacks” divers as well.

I read in one of the survival guides that the cones should only be picked up by the narrower part of the shell. In no case! It is there, in the mouth, that the head and, accordingly, the trunk with poisonous teeth are located. It is necessary to act on the contrary - to take the upper, wider part. The small number of reported cases of cone bites suggests that fears and concerns about them are, to put it mildly, exaggerated. However, these mollusks must be handled with care, as with any potentially dangerous animal, and vigilance must not be lost. Many species are best not touched at all. No one has yet died from the sting of bees, but no one will grab a bee or a wasp with his bare hand.

Poisonous predator snails January 28th, 2015

Our story is dedicated to representatives of one of the most, perhaps, the most beautiful genera of gastropods - the genus Conus. These snails got this name for the shape of their shell, which really has the shape of an almost regular cone.

If this is news to you, then snails can really be real predators. Most of the cones are not dangerous to humans. Their venom is intended for worms, other mollusks, and sometimes fish. However, there are several dozen cones whose venom can not only cause pain or paralysis, but also lead to the death of a person.

Let's find out more about them...

The cones are very different. Now there are already more than 550 species, and every year more and more new ones are described. Most of these mollusks are inhabitants of the tropics, but there are species that live in warm temperate seas, for example, in the Mediterranean.

Cone shells are valued by collectors for their amazing beauty and variety of colors. German collectors paid up to 200 thousand marks and even more for especially outstanding specimens of some types of cones. And this is not a new fashion. Back in 1796, an auction was held in Lainet, where two paintings by Franz Hals were put up for sale, the famous painting by Vermeer of Delft “Woman in Blue Reading a Letter” (now it is in the Royal Museum in Amsterdam) and a five-centimeter (just something! ) cone shell S. cedonulli ("incomparable"). The paintings by Hals sold for next to nothing, Vermeer was sold for 43 guilders, and the cone for 273 guilders!

Photo 3.

o cones are interesting not only for their shells. Equally well-known is the ability of these mollusks to inflict poisonous "bites". The venom gland is located inside the very specific "teeth" of the mollusk. These teeth, resembling hollow needles, are located at the cones on a long flexible plate - the radula. A radula is present in many gastropods, with the help of which snails scrape off pieces of food, which are then sent to the mouth. In cones, the mouth is located on a movable proboscis. A hunting mollusk (and cones are predators) first tears off one of its poisonous teeth from the radula, and then, holding this tooth clamped in its mouth, sticks it into its prey. The proboscis is compressed, and the poison from the tooth is injected into the body of the victim. Most cones feed on marine worms, but there are also mollusc-eating and fishing cones. The latter have the strongest poison. Its effect is manifested within a second after the injection. The cone swallows the immobilized victim whole and quickly digests ...

Photo 4.

But how can a snail catch a fish? Fishing cones hunt from ambush, burrowing into the sand. The mollusk learns about the approach of prey by smell, and the role of its nose is played by osphradium, an organ located in the mantle cavity at the base of the gills. Sensing a fish at close range, the cone instantly strikes with a poisonous tooth. Representatives of some species lure fish with the movements of their proboscis, resembling a worm, or special outgrowths located along the edge of the head. And the geographic cone has even adapted to “throw a net”: its entire head can stretch, acquiring the form of a funnel up to 10 cm in diameter. A stupid fish swims into this funnel.

Photo 5.

The poison of cones - conotoxin - was first studied by the American B. Olivera. It is a mixture of a large number of low molecular weight peptides containing 10–30 amino acids. Its action is similar to the action of cobra venom - it blocks the transmission of a signal from the nerves to the muscles. As a result, the bitten quickly develops numbness, and then death occurs as a result of cardiac arrest. When scientists synthesized conotoxins and began to study their action, it turned out that the substances that make up the poison can not only lead to death, but also cause sleep, relieve convulsions or, conversely, cause them. In addition, peptides were discovered with a very strange effect - mice that were injected with them began to jump and climb walls. Another conotoxin, called "King Kong", had no effect on warm-blooded animals, but made molluscs crawl out of their shells!

In short, the poisons of the cones turned out to be very diverse, unusual in action and very promising for medicine. Already, drugs are being created on their basis, for example, against epileptic seizures. Or painkillers, similar in their action to morphine, but not addictive.

Photo 6.

But drugs are drugs, and the cones themselves must be treated with great care. They use their "sting" not only when hunting, but also for protection in case of danger. So, if you happen to go to the tropics and swim in the warm tropical sea, beware of touching unfamiliar shells, even if they are very beautiful. And in no case do not touch the mouth in the lower, narrow part - this is where the cones have poisonous teeth. The poison of the cones is very strong, and the injections of some species, in particular, the geographic cone, can be fatal. There is no antidote, and the only way to save is profuse bloodletting from the injection site.

Photo 7.

A new study shows that at least two species of cone snails have turned insulin into a real weapon of underwater combat. When these aquatic predators approach their prey, they release insulin, a hormone that causes blood sugar levels to plummet.

There is no chance for a fish nearby. The surge of insulin penetrates the gills and enters the bloodstream - and in a matter of moments the fish does not have enough energy to swim away and avoid the fate of being eaten.

Study lead author Helena Safavi, a professor of biology at the University of Utah, and her colleagues discovered "weapon-grade" insulin while screening the venoms of various species of cone snails. More than 100 species of these underwater predators are known to be about 15 centimeters long, which release complex toxins to paralyze their victims. In the past, scientists have even used cone venom to create drugs, such as the anesthetic ziconotide (trade name Prialt), which is 1,000 times more potent than morphine and mimics the toxin from the snail Conus magus.

Photo 8.

Cones that use small harpoons to inject their food don't use insulin, but two species - Conus geographus and Conus tulipa - have adopted this hormone.

Humans produce insulin in their pancreas, but shellfish produce it in their neuroendocrine cells. And, surprisingly, two types of these found cones produce ordinary insulin in neuroendocrine cells, and the "weapon" one - in its poisonous gland.

Photo 9.

The shell of a Conus geographus that uses insulin to hunt fish

Another curious fact is that the insulin found in the cones is the shortest molecular insulin discovered to date. Perhaps this is a consequence of its highly specialized task - to lower the level of sugar in snail prey. Now its study can help scientists in the development of new drugs for the treatment of diabetes.

The following subspecies of snails are considered the most poisonous: geographic cone (Conus geographus), brocade cone, tulip cone, marble cone and pearl cone.

Photo 10.

sources

Based on materials: Yu.I. Cantor / Nature. 2003. No. 10

Those who first come to the Red Sea are impressed by the abundance of beautiful shells. They can be bought from merchants, found ashore, or seen live snorkeling in coral reefs.
The most common are cones. There are already 550 known species, and at least a dozen new ones are described annually. This is the most collectible and expensive type of shells. They range in size from two to ten to fifteen centimeters. They are found in all oceans and even in the Mediterranean Sea. The fact that almost all cone snails are poisonous has long been known. Their venom is comparable to cobra venom, but much more toxic than it. When bitten, numbness of the body and cardiac arrest quickly develop. There is no antidote, since the poison of the cone consists of more than 50 low molecular weight peptides containing 20-30 amino acids. It acts instantly, the fish is immobilized in 2-3 seconds.

For a person, the bite of any kind of Cone is extremely dangerous. Leading geographic cone- the mortality rate caused by the injection of this mollusk is 70%. The real salvation from death is the method used by the Papuans of New Guinea - profuse bloodletting and heart massage.

Now think about whether it is worth picking up beautiful shells among corals or is it better to limit yourself to observation from the outside.
To such a gloomy description, one should add: of course, it is not every day that a stretcher with victims is taken away from hotels. And cones don't always sting. Two years ago, unknowingly, I collected them with my bare hands (photo attached). And of course, it’s not a fact that you will come across a deadly poisonous Geographic cone, but remember - out of ten bitten by it, only three survive. It is a fact.

The sting at the cone is located in the channel of the narrow part of the shell. If you want to be sure to pull it out of the water, take it by the wide part of the sink.
Resting in Egypt, and snorkeling, you will surely see a lot of interesting things under water. Tip - do not touch anything with your hands, it is better to buy an underwater camera. There will be no less impressions, but you will save your health.

Another no less interesting representative of the Red Sea fauna is TRIDACNIDAE - Giant clam. Beautiful shell from 10 to 30 cm, partially or completely grown into the reef, with beautiful turquoise or blue wavy edges.

giant bivalve mollusk - Tridacn.
They look like funny and beautiful scallops, but in fact this is the famous giant killer clam. Specimens weighing 100 - 200 kg are known. The principle of "murder" is simple - the shell is ajar, and inside the pearl shines. You can stick your hand behind it, you can't pull it out. The flaps close quickly and very tightly. Such a trap cannot be unclenched even with a mount. There are cases when divers died in such a trap. The story in which the poor fellow had to cut off his hand in order to free himself and survive is not officially confirmed, but it is quite acceptable. There is other information - when human remains were found in a one and a half meter shell. Given the size and force of compression of the valves, such an outcome is quite possible. This is the oldest and largest bivalve mollusk on earth. On average, its dimensions are: 30 - 40 cm, but there are specimens one and a half - two meters long, and weighing at least half a ton. And they live 200 - 300 years or more.

This gastropod is not only the most dangerous member of the cone family, but also the most poisonous snail in the world. Its scientific name is geographic cone. Habitat - Indo-Pacific region. The mollusk prefers to live in warm waters in shallow water, therefore it poses a real threat to tourists, who, most likely, are not even aware of its existence.

Armed and very dangerous

The geographic cone is a predator that prefers to hunt small fish, worms. The mollusk has a proboscis-like sting through which it injects a highly toxic venom into its prey. Since the speed of movement of the geographic cone along the ocean floor is too low, it prefers to take a wait-and-see position. As soon as the prey swims or crawls nearby, the mollusk attacks with lightning speed. The victim receives a lethal dose of poison that instantly paralyzes them. The geographic cone swallows its lunch whole.

How can a meeting with a mollusk end?

Unlike most mollusks, which prefer to hide in the shell when meeting with a person, the geographic cone acts quite aggressively, often attacking first. A cone attack can result in a painful bite that feels like a burn. After that, the stung place begins to lighten, and then turn blue. The affected area becomes numb.

Despite its relatively small size (up to 10 centimeters in diameter), the mollusk poses a deadly threat to humans. Over the past decade, the geographic cone has killed more than thirty people. As a rule, death occurs due to drowning. If the stung is in the water away from the coastline, then he simply does not have time to swim to the shore. Nerve poison leads to partial or complete paralysis of the body, and the victim loses the ability to swim.

At the moment, there is no effective antidote that could negate the effect of this poison on the human body. Therefore, there are cases when tourists died after being bitten by a geographic cone while in a hospital bed. To save life, experts recommend making a deep incision at the site of the bite for profuse bloodletting.

Action of the poison

The geographic cone, like other members of this family, produces a poison, the scientific name of which is conotoxin. The first studies of the toxic substance with which the mollusk kills its prey were carried out by the American professor B. Oliver. From his report it becomes clear that conotoxin is a mixture of a huge amount of low molecular weight peptides that contain up to 30 amino acids. Based on this, it can be argued that the effect of the poison of the geographic cone is similar to that of the cobra. It partially or completely blocks the transmission of impulses from nerves to muscles. The victim, struck by the poison of the geographic cone, rapidly develops numbness, after which an agonizing death occurs due to cardiac arrest.

To prevent your vacation from ending up in a hospital bed, experts recommend avoiding any tactile contact with the geographic cone. This mollusk is quite often found in the Red Sea, which washes the shores of Egypt, which is so fond of tourists from Russia.

If you dive under water, for example, in scuba gear, to admire the nature of the underwater world, then try not to touch anything. As a rule, the cone burrows into the sand and sits in ambush. As soon as he realizes that you are too close, he will go on the attack and try to sting.

Use of poison in medical forces

Despite the mortal danger of the geographic cone, it, like many other poisonous representatives of the animal world, is of great interest to employees of the biomedical profile. The toxic nerve poison that these mollusks produce can not only cause serious damage to the body, but also be very useful.

The geographic cone produces a venom containing a huge amount of proteins that can be used as an anesthetic. According to recent studies, with the help of these protein compounds, it is possible to selectively act on certain human pain receptors, and the result from their use is several thousand times greater than the effect of morphine. But unlike the latter, the poison of the geographic cone does not cause addiction.

Also, from the toxic substance that mollusks produce, scientists have learned how to extract “pure” conotoxins. Based on them, drugs are produced that help people suffering from convulsive seizures to significantly reduce their number.

The first written mention of a geographical cone dates back to 1777. Then the shell of this mollusk was considered the most beautiful, rare and valuable in the world. Collectors were ready to shell out several thousand dollars just to get a precious shell, which became a real gem of any collection.

The situation changed dramatically in the middle of the twentieth century, when scientists explored the entire habitat of the geographical cone. As it turned out, there are a lot of these mollusks in the Indo-Pacific region, and some tribes living on the coast even decorated the walls of their houses with shells. To date, the cost of a cone shell varies within ten dollars, and they can be purchased on popular Internet sites, for example, AliExpress.