Few people expect a trick from a snail. Many are accustomed to being a little condescending to these unusual animals. Who are they, these snails? And can a freshwater snail really be dangerous?
Name
The snail is a representative of the animal kingdom. It belongs to the type of mollusk, 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 mode of locomotion, while Russian emphasized the hollow house the animal carries on its back.
Typical structure
A snail is a typical gastropod mollusk with an outer shell and body. It is surprising that the body simultaneously performs the functions of movement and the abdomen. Above it is a special fold, which is called the mantle. The void between the mantle and the body is called the mantle cavity. Inside it is the inlet siphon, which passesinside water enriched with oxygen, and an outlet siphon designed to remove the waste fluid. As you understand, this applies to those snails that live in the water. If the animal is a land animal, then a primitive lung is located in the mantle cavity, not gills.
Species details
There are quite a lot of gastropods in nature. Scientists have recorded over 110 thousand species. All of them are divided into 3 main subgroups:
- sea views;
- freshwater species;
- land snails.
In fact, the division can be reduced to gill and lung 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 animal harmless, which annually accounts for about 10,000 deaths? This is not an exaggeration at all. Are you interested in the dangers of freshwater snails? How can an animal that does not have sharp fangs and long claws kill a person? Let's explain now.
A huge amount of garbage, including animal and human waste, enters fresh water every day. In dirty water, various parasites multiply massively. Microscopic parasites from the genus Schistosoma settle on the body of freshwater snails, which infect humans.
Freshwater killer snail causes terriblea disease called schistosomiasis. A huge number of parasites penetrate the skin and begin their reproduction. According to the international classification, schistosomiasis is the second most common tropical disease (after malaria) in the world. It is estimated that more than 207 million people on the African continent alone suffer from schistosomiasis, but these are only those who could seek help. According to statistics, 25% of people who get sick die.
How infection occurs
Freshwater snails kill people by infecting bodies of water 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, do laundry, drink water from contaminated reservoirs, and sometimes simply wade through them. In fresh water there are snails, in the body of which sporocysts settle, from which caecariae develop. They leave the body of snails and move freely in the water, penetrating through the human skin into the circulatory system. Through large vessels and capillaries, caecaria migrate to the portal vein or bladder.
In the process of migration, the form of parasites changes again, they become adult male and female worms. The special composition of the protein structure of schistosomes makes them hardly noticeable or even invisible to the human immune system. This makes it possible for parasites to breed in incredible numbers. An immune reaction occurs only after heterosexual individuals have mated and laid eggs. Through the intestines or bladder, the eggs are released back into the environment. From the water, the eggs again enter the body of the molluscs. And then the freshwater snails kill again, continuing the schistosome cycle.
It takes about 65 days 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.
The freshwater snail, which is a necessary step in the life cycle of schistosomes, is common in the waters of 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 eggs of parasites accumulate in the body. Initially, after visiting dangerous areas, you should pay attention to redness and irritation of the skin from contact with fresh water.
After 1-2 months after infection with parasites, primary symptoms appear. They are expressed in a feverish state, chills, coughing and muscle soreness. But most of the infected primary symptoms do not feel. They realize that they are sick only when chronic schistosomiasis develops. The symptoms of this disease are:
- severe abdominal pain;
- ascites, that is, swelling;
- diarrhea with blood;
- pain when urinating, blood in urine;
- shortness of breath;
- coughing fits;
- palpitations, pain in the heart area;
- partial or complete paralysis;
- mental disorders.
Examination, tests, treatment
If, after returning from a vacation or a business trip from countries where schistosomiasis is highly common, a person begins to experience strange ailments, then you should immediately contact a parasitologist or infectious disease specialist. Especially if, while visiting local attractions, a person came into contact with the water of rivers or lakes. At the same time, in a reservoir where a freshwater snail is found, it is not necessary to swim. It is enough to sit on the shore with your feet in the water, or put your hand in the water for a long time during a boat trip.
The symptoms of schistosomiasis are similar to other infectious diseases, so several stool and urine tests are necessary. 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 difficult cases, a colonoscopy, cystoscopy, or biopsy may be needed. Ultrasound diagnostics, x-rays, MRI and other examinations can be used to determine the degree of infection.
Praziquantel is prescribed as a treatment. The dosage is calculated based on the weight of the patient, the duration of administration is determined by the doctor. To enhance the effect, it is possible to combine with the drug "Artesunate".
After the course of treatment, the patient should receive an appointment for stool and urine tests to make sure that the parasites have died.
Freshwater snails. Predator-helena
There are various types of freshwater snails that live both in open water 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's shell features contrasting black and amber stripes. The head of the mollusk is elongated like a proboscis. Helena's body is mottled, it is covered with thousands of black dots. Nature has provided this dangerous predator with special lamellar protection. In dangerous situations, the snail closes the entrance to the shell with a strong "door".
Helena clams are often kept as freshwater aquarium snails. They help reduce algae, tadpoles, pond snails and other snails.
Horned snail
These freshwater molluscs belong to the famous Neritina family. They are distributed in southern latitudes. They are found in the waters of Japan, Thailand, the Philippines, China and Indonesia. The mollusk prefers estuaries with stone or sandy bottoms.
The snail has natural protection in the form of sharp growths. The horns scare away predators trying to grab the snail.
The color of the shells consists of two colored stripes. One is yellow, the other is black. Small bright inhabitants often get to the owners of freshwater aquariums. They clean up excess algae from snags, decorations and glass. Horned mollusks get along well with other inhabitants of aquariums, the only exception is, perhaps,snail helena.
Snail snail
Freshwater snail is found in the waters of South America and Asia. These are beautiful multi-colored molluscs with four sharp antennae on the body. The color range of ampoule is surprisingly diverse. This is a whole family of molluscs, 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, the presence of gills and a lung can be called. This is due to the fact that the species lives in shallow water bodies. Ampoules have a special process, stretching out which they can breathe atmospheric air, even while in water.
Ampoules 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 hibernate, closing the sink with a lid.
Aquarists love members of this family for keeping the bowl clean. Ampoules pick up bits of food and dead algae that have settled to the bottom.
Snail chalking
This gastropod species is distributed throughout Africa and has a very wide range. Under natural conditions, it prefers small ponds with a slow current. But melania does not like a rocky bottom, prefers a silty pillow or sand. The basis of the diet of this snail is lower algae and semi-decomposed remains of organic matter. Melania shell is elongated with a sharp tip. The color range varies from black to light brown.brown.
Virtually any freshwater snail you find in a photo will look beautiful and attractive. However, we must not forget that these mollusks carry a huge danger. If the owner of the aquarium wants to have such a pet, adding it to other fish, then he must understand that security measures must be taken.
Whether you caught snails yourself or bought them in a pet store, all mollusks must be kept in quarantine. Freshwater snails are planted in an empty aquarium (without algae and other inhabitants) and kept for about 4 weeks in a weak solution of potassium permanganate. Then the animal is washed in clean water and only after this procedure is allowed into the general aquarium. Although, remembering how dangerous a freshwater snail is for humans, it is undesirable to catch this animal in natural reservoirs. Why expose yourself to schistosomiasis?
