Few people expect a catch from a snail. Many are used to being a little down on these unusual animals. Who are these snails? And is a freshwater snail really dangerous?
Title
The snail is a representative of the animal kingdom. It is classified as a mollusk, a class of gastropods, or gastropods. The Latin name Gastropoda is formed from two ancient Greek words, the approximate meaning of which is “belly” and “leg”. And the Russian name of this animal - "snail" - has Old Slavonic roots. It is consonant with the adjective “hollow”. It turns out that each name reflected one of the features of the mollusk. Latin concentrated on the method of transportation, and the Russian language was emphasized by the hollow house that the animal wears on its back.
Typical building
The snail is a typical gastropod mollusk with an external shell and trunk. The amazing thing is that the body simultaneously performs the functions of movement and the abdomen. Above it is a special fold called the mantle. The void between the mantle and the body is called the mantle cavity. Inside it there is an inlet siphon, which passes oxygen-enriched water, and an outlet siphon, designed to remove the spent liquid. As you know, this applies to those snails that live in water. If the animal is land, then in the mantle cavity there is a primitive lung, not gills.
Species Information
In the nature of gastropods there are quite a lot of mollusks. Scientists have recorded over 110 thousand species. All of them are divided into 3 main subgroups:
- marine species;
- freshwater species;
- land snails.
In fact, the separation can be reduced to gill and pulmonary forms. But we will try to take a closer look at only one of the forms. It will be a freshwater snail.
Freshwater Snails: Danger
The most terrible killers on earth are not large predators, but small harmless snails. Although how can you call an innocuous animal, on whose account annually about 10, 000 deaths? This is not an exaggeration. Are you interested in what are dangerous freshwater snails? How can an animal without sharp fangs and long claws kill a person? We will explain now.
Every day, a huge amount of garbage, including animal and human wastes, gets into fresh water. Various parasites multiply in dirty water. Microscopic parasites from the genus Schistosoma infect humans on the body of freshwater snails.
A freshwater killer snail causes a terrible disease called schistosomiasis. A huge number of parasites penetrate the skin and begin their reproduction. According to international classification, schistosomiasis is the second (after malaria) tropical disease in terms of prevalence in the world. It is estimated that in the African continent alone more than 207 million people suffer from schistosomiasis, but these are only those who could ask for help. According to statistics, 25% of sick people die.
How does infection happen?
Freshwater snails kill people by infecting ponds with schistosome larvae. It is in their organisms that the larvae go through the first phase of development. The life cycle of schistosomes is quite complex. People bathe, wash, drink water from infected ponds, and sometimes just wade them. In fresh water bodies there are snails in the body of which sporocysts settle, from which cecaria develop. They leave the body of the snails and move freely in the water, penetrating through the human skin into the circulatory system. In large vessels and capillaries, cecaria migrate into the portal vein or into the bladder.
In the process of migration, the form of parasites changes once again, they become adult male and female worms. The special composition of the protein structure of schistosomes makes them subtle or even invisible to the human immune system. This makes it possible to breed parasites in an incredible amount. An immune reaction occurs only after heterosexual mates mate and lay eggs. Eggs enter the environment through the intestines or bladder. From the water, the eggs again enter the mollusk's body. And then freshwater snails kill again, continuing the development cycle of schistosomes.
About 65 days pass from the penetration of chicaria into the skin to the development of a sexually mature individual capable of reproduction. The female is larger than the male. It can grow from 7 to 20 mm. Schistosomes live from 3 to 30 years, producing billions of eggs during this time.
Freshwater snail, which is a necessary step in the life cycle of schistosomes, is common in water bodies in Africa, the Middle and Far East, South America and the Philippines.
How to understand that an infection has occurred
Symptoms of schistosomiasis are dangerous because they do not appear immediately, but when a huge number of parasite eggs accumulate in the body. Initially, after visiting hazardous areas, it is worth paying attention to redness and skin irritation from contact with fresh water.
1-2 months after infection with parasites, primary symptoms appear. They are expressed in fever, chills, coughing and muscle soreness. But most of the infected primary symptoms do not feel. They understand that they are sick only when chronic schistosomiasis develops. Symptoms of this disease are:
- severe abdominal pain;
- ascites, i.e. bloating;
- diarrhea with blood;
- pain during urination, blood in the urine;
- dyspnea;
- coughing attacks;
- palpitations, pain in the heart;
- partial or complete paralysis;
- mental disorders.
Examination, analysis, treatment
If, after returning from vacation or a business trip from countries where schistosomiasis is very common, a person begins to experience strange ailments, then you should immediately contact a parasitologist or infectious disease specialist. Especially if, during a tour of local attractions, a person came into contact with the water of rivers or lakes. At the same time, it is not necessary to swim in the pond where the freshwater snail is found. It is enough to sit on the beach, lowering your feet into the water, or to lower your hand in the water for a long time during a boat excursion.
Symptoms of schistosomiasis are similar to other infectious diseases, so it is necessary to pass several tests of feces and urine. Blood tests (PCR) show the presence of a problem only in the advanced stage of the disease, since the immune response does not immediately appear.
In complex cases, a colonoscopy, cystoscopy, or biopsy may be necessary. Ultrasound diagnostics, X-ray, MRI and other examinations can be used to identify the degree of infection.
As a treatment, Praziquantel is prescribed. The dosage is calculated based on the weight of the patient, the duration of the reception is determined by the doctor. To enhance the effect, a combination with the drug "Artesunate" is possible.
After the course of treatment, the patient should receive an appointment for feces and urine tests to make sure that the parasites have died.
Freshwater snails. Helena Predator
There are various types of freshwater snails living both in open water bodies and in freshwater aquariums. One species is the Helena snail. This dangerous beauty lives in Southeast Asia. It has a bright and attractive appearance and is able to eat smaller gastropods.
Helena shell is decorated with contrasting stripes of black amber color. The head of the mollusk is stretched out like a proboscis. The body of Helena is speckled, thousands of black dots cover it. Nature provided this dangerous predator with special plate protection. In dangerous situations, the snail closes the entrance to the sink with a solid “door”.
Helena mollusks are often found as freshwater aquarium snails. They help reduce the amount of algae, tadpoles, ponds and other types of snails.
Horned snail
These freshwater mollusks belong to the famous Neritina family. They are distributed in the southern latitudes. They are found in water bodies of Japan, Thailand, the Philippines, China and Indonesia. Clam prefers river mouths with a stone or sandy bottom.
The snail has natural protection in the form of sharp growths. Horns scare away predators trying to grab a snail.
The color of the shells consists of two colored stripes. One of them is yellow, the second is black. Small bright inhabitants often get to the owners of freshwater aquariums. They clean up excess algae from snags, decorations and glasses. Horned mollusks get along well with other aquarium inhabitants, perhaps the only snail helena is the exception.
Snail ampoule
Freshwater ampoule is found in water bodies in South America and Asia. These are beautiful multi-colored mollusks with four sharp antennae on the body. The color scheme of ampoule is surprisingly diverse. This is a whole family of mollusks, in which there are at least 120 species, each of which has its own color. The body of the mollusk can reach 7 cm in length. Of the features of the species can be called the presence of gills and lungs. This is due to the fact that the species lives in shallow water bodies. Ampouleria have a special process, stretching which, they can breathe atmospheric air, even when in water.
Ampularians love warm water (up to 28 ° C) and are not too whimsical in nutrition. Grated vegetables, fish food, and small fish pieces are suitable for them. If the water in the aquarium is cold, then the ampoule will go into hibernation by closing the lid of the sink.
Aquarists love this family for keeping it clean. Ampularia pick up pieces of food that have settled to the bottom and dead algae.
