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Shellfish toxin symptoms: Food Poisoning from Shellfish: Signs, Symptoms, Treatment


Washington State Department of Health

What is Diarrhetic Shellfish Poison?

Diarrhetic Shellfish Poison (DSP) is a marine biotoxin toxin produced by the dinoflagellate Dinophysis, which is a type of naturally occurring microscopic algae. Shellfish eat these algae and can retain the toxin. People can become ill from eating shellfish contaminated with Diarrhetic Shellfish Poison.

How do shellfish become contaminated with Diarrhetic Shellfish Poison?

Shellfish are filter feeders. They pump water through their systems, filtering out and eating algae and other food particles. When shellfish eat biotoxin producing algae, the biotoxin can accumulate in their tissue.

What types of shellfish are affected?

Bivalve molluscan shellfish such as clams, mussels, oysters, geoduck, and scallops can accumulate Diarrhetic Shellfish Poison.

What causes unsafe levels of Diarrhetic Shellfish Poison?

It’s normal for biotoxin-producing algae to be present in marine water. They are usually in low numbers that cause no problems. But when the algae “blooms,” the amount of biotoxin-producing algae can increase. The increased algae becomes a greater food source for shellfish. The more algae the shellfish eat, the more biotoxin they accumulate. Biotoxins don’t harm shellfish, so the level in their tissue will rise until the bloom subsides. When the number of toxin producing algal cells returns to normal low levels, the shellfish eventually flush the toxin from their bodies. It can be several days to several months or longer before they’re safe to eat again.

The algae that produces Diarrhetic Shellfish Poison toxin has been detected in Washington’s marine waters for some time, but has not produced toxin at unsafe levels until recently. In June 2011, three people became ill after eating recreationally harvested mussels from Sequim Bay. Testing confirmed the shellfish were contaminated with Diarrhetic Shellfish Poison toxin.

What causes Diarrhetic Shellfish Poison blooms?

When water conditions are favorable, the algae “blooms” and reproduces. Continuing research has pointed to certain cause and effect situations, but the exact combination of conditions that cause blooms is not yet known. NOAA Fisheries has more information about harmful algae and their toxins. 

Can I tell if the shellfish are toxic by the way they look?

No. Shellfish containing toxic levels of Diarrhetic Shellfish Poison don’t look or taste any different from shellfish that are safe to eat. Laboratory testing of shellfish meat is the only known method of detecting Diarrhetic Shellfish Poison.

Does cooking the shellfish make it safe to eat?

 No, Diarrhetic Shellfish Poison toxin isn’t destroyed by cooking or freezing.

What are the symptoms of Diarrhetic Shellfish Poisoning?

Diarrhetic Shellfish Poisoning causes nausea, vomiting, abdominal pain, and diarrhea. Diarrhea is the most commonly reported symptom.

Who is most at risk?

Anyone who eats Diarrhetic Shellfish Poison contaminated shellfish is at risk for illness. The Diarrhetic Shellfish Poison toxin is non-lethal to humans.

What should I do if I think I have Diarrhetic Shellfish Poisoning?

If symptoms are mild, call your health care provider and your local public health agency. If symptoms are severe, call 911 or have someone take you to your family doctor.

How can I protect myself from Diarrhetic Shellfish Poisoning?

Check the Shellfish Safety Map for beach closures and advisories on the day you plan to harvest shellfish. 

We regularly test shellfish for biotoxins and close areas when unsafe levels are detected. Beaches are sometimes posted with warning signs. Don’t assume a beach is safe if there are no signs – beach closure signs sometimes “disappear.”   

Other options to check if a beach is open or closed include: 

Are there any other illnesses associated with shellfish?

Yes. Other types of biotoxins found in the northwest can cause Paralytic Shellfish Poisoning and Amnesic Shellfish Poisoning. Harmful bacteria can cause vibriosis. Raw sewage contamination can cause norovirus illness. Some people can have an allergic reaction to shellfish.   

What about shellfish offered by restaurants, stores, and farmers’ markets? Are they safe to eat?

Shellfish harvested commercially and sold to the public come from licensed, certified growers. Commercial harvest operations must meet stringent state and federal health standards, and the shellfish they harvest are regularly tested for biotoxins. 

More Resources

Biotoxins and Shellfish-Related Illnesses

Prevent Shellfish-Related Illnesses

Handout – Diarrhetic Shellfish Poisoning (PDF)

Washington State Department of Health

What is Paralytic Shellfish Poison?

Paralytic Shellfish Poison (PSP) is a naturally occurring marine biotoxin that is produced by some species of microscopic algae. Shellfish eat these algae and can retain the toxin. People can become ill from eating shellfish contaminated with Paralytic Shellfish Poison. This biotoxin affects the nervous system and paralyzes muscles, thus the term “paralytic” shellfish poison. High levels of Paralytic Shellfish Poison can cause severe illness and death.

How do shellfish become contaminated with Paralytic Shellfish Poison?

Shellfish are filter feeders. They pump water through their systems, filtering out and eating algae and other food particles. When shellfish eat biotoxin producing algae, the biotoxin can accumulate in their tissue.

What types of shellfish are affected?

Bivalve molluscan shellfish such as clams, mussels, oysters, geoduck, and scallops can accumulate Paralytic Shellfish Poison. So can moon snails and other gastropods. Other marine species, such as sea cucumbers, might be affected. Crab, because they feed on shellfish, can also become toxic. Even if the crab meat is safe, toxins tend to accumulate in crab gut and butter (the white-yellow fat inside the back of the shell). Clean crab thoroughly and avoid eating the crab butter and guts.  

What causes unsafe levels of Paralytic Shellfish Poison?

It’s normal for biotoxin producing algae to be present in marine water. They are usually in low numbers that cause no problems. But when the algae “blooms,” the amount of biotoxin-producing algae can increase. The increased algae becomes a greater food source for shellfish. The more algae the shellfish eat, the more biotoxin they accumulate. Biotoxins don’t harm shellfish, so the level in their tissue will rise until the bloom subsides. When the number of toxin producing algal cells returns to normal low levels, the shellfish eventually flush the toxin from their bodies. It can be several days to several months or longer before they’re safe to eat again.

What causes Paralytic Shellfish Poison blooms?

When water conditions are favorable, the algae “blooms” and reproduces. Continuing research has pointed to certain cause and effect situations, but the exact combination of conditions that cause blooms is not yet known. NOAA Fisheries has more information about harmful algae and their toxins. 

If the water looks dirty or red, does that mean the shellfish are contaminated?

Not necessarily. Paralytic Shellfish Poison is rarely associated with a red tinge to the water.

Isn’t “Red Tide” the same as Paralytic Shellfish Poison?

The term “red tide” is commonly used to describe toxic blooms. This isn’t quite accurate. Some algal blooms turn water different colors, including red, but many of these blooms are not harmful. The National Office for Harmful Algal Blooms has photos of different types of algal blooms.  

If the water isn’t red, does that mean the shellfish are safe to eat?

Not necessarily. Paralytic Shellfish Poison can be present in large amounts even if the water looks clear. Also, the toxin can remain in shellfish long after the algae bloom is over.

Can I tell if shellfish are toxic by how they look?

No. Shellfish containing toxic levels of Paralytic Shellfish Poison don’t look or taste any different from shellfish that are safe to eat. Laboratory testing of shellfish meat is the only known method of detecting Paralytic Shellfish Poison.

Does cooking the shellfish make it safe to eat?

No. Paralytic Shellfish Poison isn’t destroyed by cooking or freezing.

What are the symptoms of Paralytic Shellfish Poisoning?

Early symptoms include tingling of the lips and tongue, which may begin within minutes of eating toxic shellfish or may take an hour or two to develop. Symptoms may progress to tingling of fingers and toes and then loss of control of arms and legs, followed by difficulty in breathing. Some people feel nauseous or experience a sense of floating. If a person consumes enough toxin, muscles of the chest and abdomen become paralyzed, including muscles used for breathing, and the victim can suffocate. Death from Paralytic Shellfish Poison has occurred in less than 30 minutes.

Who is most at risk?

Anyone who eats Paralytic Shellfish Poison contaminated shellfish is at risk for illness or death.

What should I do if I think I have Paralytic Shellfish Poisoning?

If symptoms are mild, call your health care provider and your local public health agency. If symptoms are severe, call 911 or have someone take you to the emergency room immediately.

What is the treatment?

There is no antidote for Paralytic Shellfish Poison. The only treatment for severe cases is the use of life support systems such as a mechanical respirator and oxygen until the toxin passes from the victim’s system. Survivors can have a full recovery.

How can I protect myself from Paralytic Shellfish Poisoning?

Check the Shellfish Safety Map for beach closures and advisories on the day you plan to harvest shellfish. 

We regularly test shellfish for biotoxins and close areas when unsafe levels are detected. Beaches are sometimes posted with warning signs. Don’t assume a beach is safe if there are no signs – beach closure signs sometimes “disappear.”   

Other options to check if a beach is open or closed include: 

Are there other illnesses associated with shellfish?

Yes. Other types of biotoxins found in the northwest can cause Amnesic Shellfish Poisoning and Diarrhetic Shellfish Poisoning. Harmful bacteria can cause vibriosis. Raw sewage contamination can cause norovirus illness. Some people can have an allergic reaction to shellfish.   

What about shellfish offered by restaurants, stores, and farmers’ markets? Are they safe to eat?

Shellfish harvested commercially and sold to the public come from licensed, certified growers. Commercial harvest operations must meet stringent state and federal health standards, and the shellfish they harvest are regularly tested for biotoxins.

More Resources

Biotoxins and Shellfish-Related Illnesses

Prevent Shellfish-Related Illnesses

Gathering Safe Shellfish in Washington, Avoiding Paralytic Shellfish Poisoning – UW (PDF)

Handout – Paralytic Shellfish Poisoning (PDF)

fish and shellfish: MedlinePlus Medical Encyclopedia

The harmful substances that cause ciguatera, scombroid, and shellfish poisonings are heat stable, so no amount of cooking will prevent you from becoming poisoned if you eat contaminated fish. Symptoms depend on the specific type of poisoning.

Ciguatera poisoning symptoms can occur 2 to 12 hours after eating the fish. They include:

Shortly after these symptoms develop, you will start to have strange sensations, which may include:

  • A feeling that your teeth are loose and about to fall out
  • Confusing hot and cold temperatures (for instance, you will feel like an ice cube is burning you, while a match is freezing your skin)
  • Headache (probably the most common symptom)
  • Low heart rate and low blood pressure (in very severe cases)
  • Metallic taste in the mouth

These symptoms may get worse if you drink alcohol with your meal.

Scombroid poisoning symptoms most often occur immediately after eating the fish. They may include:

  • Breathing problems, including wheezing and chest tightness (in severe cases)
  • Extremely red skin on the face and body
  • Flushing
  • Hives and itching
  • Nausea and vomiting
  • Peppery or bitter taste

Below are other well-known types of seafood poisoning, and their symptoms.

Paralytic shellfish poisoning: About 30 minutes after eating contaminated seafood, you may have numbness or tingling in your mouth. This sensation may spread down to your arms and legs. You may become very dizzy, have a headache, and, in some cases, your arms and legs may become temporarily paralyzed. Some people may also have nausea, vomiting, and diarrhea, although these symptoms are much less common.

Neurotoxic shellfish poisoning: The symptoms are very similar to those of ciguatera poisoning. After eating contaminated clams or mussels, you will most likely experience nausea, vomiting, and diarrhea. These symptoms will be followed soon after by strange sensations that may include numbness or tingling in your mouth, headache, dizziness, and hot and cold temperature reversal.

Amnesic shellfish poisoning: This is a strange and rare form of poisoning that begins with nausea, vomiting, and diarrhea. These symptoms are followed by short-term memory loss, and other less common nervous system symptoms.

Shellfish Poisoning – an overview

Single administration

After single i.p. injection in mice, the LD50 of OA ranged from 192 to 225 µg/kg (Tubaro et al., 2008a). An LD50 of 352 µg/kg was determined for DTX-2, and a relative potency of 0.6 was estimated compared to that of OA, which was ascribed to the axial 35-methyl group of DTX-2 that would give rise to lower affinity for PP2A (Aune et al., 2007; Huhn et al., 2009). Intraperitoneal injection of OA or DTX-1 (≥200 and 375 µg/kg) in rodents (mice and rats) induced damages in the intestinal mucosa, particularly the duodenum and upper part of the jejunum, within 15 min. The injuries can be divided into three consecutive stages: increased capillary permeability and extravasation of serum into the lamina propria of villi, degeneration of absorptive epithelium of villi, and desquamation of the degenerated epithelium from the lamina propria. At sublethal doses, these alterations are reversible, and the recovery process, observed already after 2 h, is complete within 24 h (Terao et al., 1986, 1993; Ito and Terao, 1994). Morphological changes induced by DTX-3 are less pronounced and consist only of dilation of the cisternae of the Golgi apparatus and the presence of vesicles in the cytoplasm of the absorptive epithelium (Terao et al., 1993). Intraperitoneal injection of OA, DTX-1, or DTX-3 in rodents also induces liver damage, with vacuolization and/or necrosis of hepatocytes (Terao et al., 1993; Ito and Terao, 1994; Aune et al., 1998; Tubaro et al., 2003).

OA-induced liver damage also occurs after i.v. injection in rats, with congestion of blood in the liver and dissolution of hepatic bile canalicular actin sheaths (Berven et al., 2001).

OA, DTX-1, and DTX-3 are less toxic orally than intraperitoneally. By the oral route, the LD50 of OA in mice ranges between 1 and 2 mg/kg (Tubaro et al., 2003). In addition to diarrhea, the signs of toxicity are similar to those observed after i.p. injection. DTX-1 and DTX-3 also cause the degeneration of surface cells of the gastric mucosa (Terao et al., 1993; Ito and Terao, 1994; Ito et al., 2000; Berven et al., 2001).

Repeated administration

Daily repeated oral OA administration in mice (1 mg/kg/day for 7 days) induced diarrhea, body weight loss, reduced food consumption, and death of two of five mice after 5 days. Toxic effects are noted in forestomach and liver, whereas ultrastructural changes are seen in cardiomyocytes (mitochondria and fibers) (Tubaro et al., 2004).

Mutagenic and genotoxic activity

Although OA is not mutagenic in S. typhimurium in the absence or presence of metabolic activation, it is mutagenic in various eukaryotic cells in vitro (Aune and Yndestad, 1993; Fessard et al., 1996). No genotoxicity data are available for DTX-2 and DTX-3. Genotoxic effects of OA, such as micronuclei formation, mitotic arrest, and polyploidy, were observed in human Caco-2 cells (Le Hégarat et al., 2006). OA is not reported on any of the lists of the International Agency of Research on Cancer.

Shellfish toxins – A guide to Food poisoning

Shellfish poisoning is a risk for anyone
who enjoys travelling and especially to areas of the developing world.
Many species of fish such as oysters, clams and mussels contain potent
toxins – known as marine toxins, which can cause food poisoning.

These marine toxins are caused by bacteria
and viruses which invade shellfish, and other types of fish via consumption
of contaminated algae or marine organisms in the surrounding water.

Toxins are found within the head, liver
and intestines of fish.

Types of

These include herbivorous and carnivorous
fish as well as shellfish.

Herbivorous fish are fish which feed
upon vegetable matter within oceans and seas. This includes aquatic
plants, plankton and algae (e.g. seaweeds). Examples of herbivorous
fish include trout and red snapper.

Carnivorous fish eat meat or flesh
of other animals which includes fish, seals and even humans. Examples
of these include moray eels, sea bass, piranhas and sharks.

Shellfish are found in freshwater as
well as sea water and include shrimps, prawns, oysters, cockles, clams
and mussels. They are also known as ‘filter feeding molluscs’
which means that they use a filter process as they feed upon algae and
plankton within the surrounding water.

Types of shellfish poisoning

All of these fish contain toxins which
are responsible for the following types of food poisoning:

  • Ciguatera poisoning
  • Scombroid poisoning
  • Shellfish poisoning

Ciguatera poisoning

A good example of this is ciguatera
poisoning which occurs when fish such as sea bass consume small marine
organisms known as ‘dinoflagellates’ which are found in or near
coral reefs.

These dinoflagellates contain toxins,
e.g. ciguatoxin, which is consumed by fish and increases in strength
and concentration as they move up the food chain. These toxins are highly
potent by the time they reach the human food chain.

Once consumed by humans they cause
ciguatera food poisoning – an unpleasant gastrointestinal illness
which is followed by neurological symptoms such as depression and fatigue.

Ciguatera poisoning is discussed in
more detail within our fish
food poisoning

Scombroid poisoning

Scombroid poisoning occurs when fish
has decayed or become ‘spoiled’ due to inadequate storage, i.e.
has not been stored at the correct temperature within a fridge.

As the fish decays the bacteria within
it produce toxins such as histamines which cause symptoms very similar
to an allergic reaction. These symptoms include nausea, vomiting and
diarrhoea as well as flushing, blurred vision and a severe headache.

These symptoms usually clear up by
themselves although serious cases will require hospital treatment.

Scombroid poisoning is discussed further
in our fish
food poisoning

Shellfish poisoning

There is more than one type of food
(or fish) poisoning caused by these molluscs which include:

  • Paralytic poisoning
  • Neurotoxic poisoning
  • Diarrhoeic poisoning
  • Amnesic poisoning

These are all caused by shellfish feeding
on contaminated algae or plankton (dinoflagellates) which contain a
variety of toxins such as saxitoxin or brevetoxins.

If you eat shellfish which contain
these toxins then expect to develop one of the following forms of fish

Paralytic poisoning

This is the most common type of shellfish
poisoning. It is caused by the consumption of shellfish which contain
a number of chemicals that are derived from saxitoxin.

Saxitoxin is a neurotoxin which when
consumed, attacks the nervous system within humans as well as causing
gastrointestinal illness.

Symptoms of paralytic poisoning include:

  • Tingling
  • Burning
  • Drowsiness
  • Lack of co-ordination/clumsiness
  • Slurred speech
  • Dry mouth
  • Choking feeling in throat

This also includes the usual symptoms
of food poisoning, for example nausea, vomiting and diarrhoea.

These symptoms appear 30 minutes to
an hour after consumption and can cause serious damage such as muscle
paralysis and respiratory failure which can be fatal. This poisoning
is particularly serious in children.

Neurotoxic poisoning

Another type of poisoning which occurs
following consumption of infected shellfish. In this case, the shellfish
contain a type of toxin called ‘brevetoxins’which cause symptoms
very similar to those of paralytic poisoning or ciguatera poisoning.

Symptoms of neurotoxic poisoning include:

  • Numbness/tingling in the
    mouth, arms and legs
  • Dry mouth
  • Poor co-ordination
  • Slurring of the speech
  • Drowsiness
  • Nausea
  • Vomiting
  • Diarrhoea

This also causes both neurological
and gastrointestinal symptoms.

Recovery takes 2 to 3 days from neurotoxic

Diarrhoeic poisoning

Diarrhoea is the main symptom – hence
the name but it also includes other symptoms such as nausea, vomiting,
chills and abdominal pains.

This type of poisoning is caused by
a variety of toxins which includes okadaic acid and yessotoxin. Okadaic
acid is the toxin which is directly responsible for causing persistent

These symptoms develop very quickly,
usually within an hour after eating contaminated shellfish. They last
for a day or so and tend to resolve themselves without the need for

The one exception to this is if someone
experiences severe diarrhoea which leads to dehydration. In this case
they will require fluid replacement therapy via an intravenous drip.

Depletion of fluids caused by diarrhoea
and/or vomiting can be dealt with at home if it is not severe. This
means drinking plenty of fluids such as water and adding electrolytes
to them to replace those lost through this illness.

These electrolytes are essential minerals
such as sodium (salt) and potassium which come in powder form and can
be added to a glass of water. They can be purchased over the counter
at a local pharmacy.

Amnesic poisoning

This is a very rare form of poisoning
which occurs as a result of eating infected shellfish. These shellfish
will have consumed this when feeding upon a type of algae called ‘diatoms’
or brown algae which produces the toxin domoic acid.

This toxin is found in sardines and
anchovies as well as shellfish.

This neurotoxin causes a range of symptoms
which include:

  • Vomiting
  • Abdominal pain
  • Diarrhoea

These symptoms of gastrointestinal
illness appear within 24 hours of eating infected shellfish.

These are then followed by neurological
symptoms which include:

  • Headache
  • Mental confusion
  • Dizziness/disorientation
  • Memory loss
  • Visual disturbances
  • Seizures

In severe cases, paralysis and even
death may occur.

There is no known antidote so anyone
with these symptoms requires hospital treatment as soon as possible.

Diagnosing shellfish poisoning

This usually involves a discussion
about the symptoms, a physical examination and questions about the type
of shellfish eaten.

If there any samples available of the
infected shellfish or leftovers then these can be tested for signs of
toxins via laboratory analysis.

Treatment for shellfish poisoning

This often depends upon the species
of shellfish and the type of toxin (or toxins). But it is important
to remember that there are no specific treatments for these toxins.

As all of these forms of poisoning
cause vomiting and diarrhoea then fluids will need to be replaced which
have become depleted as a result of these. This involves drinking fluids
which contain electrolytes to restore essential vitamins and minerals.

Some cases will require hospital treatment
especially those which involve children or people with a medical condition
or a weakened immune system. This treatment will be supportive and involve
fluid replacement and medication.

Mannitol is prescribed in cases of
ciguatera poisoning and is given intravenously.

Preventing shellfish poisoning

If shellfish is cooked thoroughly and
at the correct temperature then it should not result in food poisoning.
Many species of shellfish contain bacteria such as e
and viruses which include norovirusbut these are destroyed during cooking.

One exception to this is oysters which
many people enjoy eating raw. If this applies to you then be aware that
there will always be a risk with this and any other type of raw fish.

This unfortunately, doesn’t apply
to toxins such as those found in algae and marine organisms. This also
includes ciguatera poisoning as these toxins are impervious to cooking,
freezing, salting and pickling.

So, what measures can you take to protect
yourself against shellfish poisoning?

Keep any fresh fish, e.g. tuna or mackerel
in the fridge which will prevent them from decomposing and producing
histamines which cause food poisoning.

Avoid eating any shellfish (or fish
in general) if you are travelling in developing countries. Unless you
are certain that these are free from contamination it is a good idea
to avoid any of these due to the risk of bacterial or viral food poisoning.

Do not assume that cooking infected
fish will kill these toxins because it doesn’t. Cooking these fish
at high temperatures or conversely, freezing them does not destroy their

If you are not sure about any fish,
and this includes shellfish then do not eat them.

What is toxic shellfish poisoning? | MPI

How toxins build up in shellfish

Shellfish with 2 shells (bivalve shellfish), like mussels or oysters, can filter up to 10 to 12 litres of water an hour. That’s more than 200 litres a day for each shellfish. These shellfish filter out phytoplankton (microscopic algae) and other particles as a food source. If these algae are toxic, then the toxins can build up in the shellfish and make them poisonous. These toxins can cause serious illness if you ear the shellfish.

If you get sick after eating shellfish

If someone gets sick after eating shellfish, make sure you:

  • phone Healthline for advice on 0800 61 11 16, or get medical help immediately
  • advise your nearest public health unit
  • keep any leftover shellfish in case it can be tested.

Find contact details for your nearest public health unit

Types of shellfish poisoning

There are 4 main types of poisoning in New Zealand.

Paralytic shellfish poisoning (PSP)

Safe limit: Less than 0.8mg/kg

Symptoms of PSP

Symptoms usually appear within 10 minutes to 3 hours of eating. Symptoms may include:

  • numbness and a tingling (prickly feeling) around the mouth, face, and extremities (hands and feet)
  • difficulty swallowing or breathing
  • dizziness and headache
  • nausea and vomiting
  • diarrhoea
  • paralysis and respiratory failure and in severe cases, death.
Causes of PSP

PSP is caused by a group of chemicals called the saxitoxins and gonyautoxins. These chemicals all differ in their toxicity to humans, and their proportions may vary. It depends on the species of shellfish and the species of algae producing the toxin.

Toxic algae of the species Gymnodinium catenatum, Alexandrium minutum and Alexandrium pacificum commonly cause PSP toxicity in New Zealand shellfish.

Amnesic shellfish poisoning (ASP)

Safe limit: Less than 20mg/kg

Symptoms of ASP

Symptoms usually appear within 24 hours of eating. Symptoms may include:

  • vomiting
  • nausea
  • diarrhoea
  • abdominal cramps.
Other symptoms of ASP in severe cases

In more severe cases there can be neurological symptoms. These can take up to 3 days to develop and include:

  • headache and dizziness
  • disorientation and vision disturbances
  • loss of short-term memory
  • motor weakness
  • seizures
  • profuse respiratory secretions
  • unstable blood pressure
  • cardiac arrhythmia
  • coma.
Causes of ASP

ASP is caused by a chemical called domoic acid. Symptoms are mainly gastrointestinal, especially at low toxin levels. However, about a quarter of affected people experience neurological problems including memory loss that may be significant and permanent. Symptoms first appear within 24 hours and neurological difficulties within 48 hours. Toxic algae of the Pseudo-nitzchia genus produce domoic acid.

Diarrhetic shellfish poisoning (DSP)

Safe limit: Less than 0.16mg/kg of okadaic acid equivalents

Symptoms of DSP

Symptoms usually appear within 30 minutes of eating and last for about a day. Symptoms may include:

  • diarrhoea
  • vomiting
  • nausea
  • abdominal cramps.
Causes of DSP

DSP is caused by okadaic acid and related compounds. DSP group toxins are mainly produced by the Dinophysis genus.

Neurotoxic shellfish poisoning (NSP)

Safe limit: 0.8 mg/kg brevetoxin-2 equivalents

Symptoms of NSP

Symptoms typically appear within 24 hours of eating. Symptoms may include:

  • difficulty swallowing
  • double vision
  • unsteadiness and tremors (shakes)
  • nausea and vomiting
  • diarrhoea
  • numbness, including tingling of the mouth, lips, hands, and feet
  • difficulty distinguishing between hot and cold.
Causes of NSP

In NSP cases, the toxins can attack the nervous system. The toxins are brevetoxins or brevetoxin analogs. NSP is generally produced by the Karenia, Karlodinium, or Gymnodinium genus.

Who to contact

If you have questions about toxic shellfish poisoning, email [email protected]

Food Poisoning: Symptoms, Treatment & Prevention

Symptoms of food poisoning

Symptoms of food poisoning can begin hours or days after consuming contaminated food or drink. The timing depends in part on the cause of the food poisoning. It can also depend on the amount of food or drink you consumed. Symptoms may include:

  • abdominal pain
  • diarrhea
  • fever
  • loss of appetite
  • nausea
  • vomiting
  • weakness and fatigue

Food poisoning may affect just one person or a whole group of people who are exposed to the contaminated food or drink. It depends on how much of the germ or toxin each person consumed. It also depends on how sensitive they are to the germ or toxin.

What are the symptoms of food poisoning from fish?

There are two types of food poisoning you can get from eating fish. They are ciguatera poisoning and scombroid poisoning.

Ciguatera poisoning symptoms include abdominal cramps, nausea, vomiting, and diarrhea. Symptoms can progress to headache, muscle aches, and itchy, tingly, or numbness of the skin. One early sign can be numbness of the lips, tongue, or area around the mouth. You may have a metallic taste or feel like your teeth are loose. You may notice a change in your ability to feel hot or cold temperatures. You may think something feels hot when it is actually cold.

Scombroid poisoning symptoms develop 20 to 30 minutes after you eat the affected fish. They include flushing (turning red) of the face, nausea, vomiting, hives, and abdominal pain. These symptoms are similar to other allergic reactions. Getting scombroid poisoning does not mean you are allergic to fish.

Vibrio vulnificus infection is a bacterial infection to warm, seawater fish. It’s found in shellfish (especially oysters), other seafood, or the ocean. You can get it by eating contaminated fish. You can get it from contact with a fish or the ocean (through an open cut). It is not common and not contagious. The symptoms are similar to those of general food poisoning: fever, vomiting, diarrhea, and abdominal pain. More serious symptoms include a high fever, chills, low blood pressure, redness, swelling, and blisters on your skin. If the bacteria enters an open cut, it can become a more serious infection. Once that happens, it can spread through your bloodstream and become life-threatening. Blood and stool tests lead to a diagnosis. Your doctor also may look at the blisters on your skin.

You can reduce your risk of exposure by not eating undercooked shellfish and other seafood. Wash kitchen utensils in hot, soapy water. Wear gloves when handling the fish if you have an open cut. Avoid ocean water until your cut or wound has healed.

Antibiotics are often used to treat the infection. In severe cases, you may need surgery or amputation where a cut or wound was infected with the bacteria.

90,000 Marine toxins (saxitoxin, tetrodotoxin, conotoxin) – Symptoms, diagnosis and treatment

Diagnosis of exposure to marine toxins is clinical, based on signs and symptoms, a history of eating seafood or shellfish, picking shellfish, swimming or hunting at sea, diving or maintaining an aquarium.

Confirmation of the diagnosis is carried out by the relevant authorities by detecting the toxin in the body of the shellfish or fish.

Symptomatic therapy is the mainstay of treatment, as there are no effective antidotes for these toxins.

Most patients recover completely with appropriate treatment. Some patients may have neurological symptoms for several days or weeks, but full recovery can be expected after some time.

Marine toxins are a heterogeneous group of compounds produced by representatives of marine flora and fauna, potentially dangerous to humans.Damage to marine toxins occurs through direct contact with them or by ingestion of poisonous sea creatures or contaminated seafood.

This section covers the following neurotoxins: tetrodotoxin, saxitoxin and conotoxin.

The indicated toxins can cause various gastrointestinal and neurological syndromes by blocking sodium channels of excitable cells of the heart, muscles and nervous tissue. After direct contact, symptoms of paresthesia in the mouth area, weakness, general sensory disturbances and ataxia may occur.While the symptoms depend on the specific types of poison, the actual manifestations of poisoning occur, as a rule, rather quickly: after contact, it takes from several minutes to several hours. Rarely enough, severe intoxication is observed that can cause atonic muscle paralysis, respiratory failure and death. [1] Centers for Disease Control and Prevention. Biosafety in microbiological and biomedical laboratories (BMBL) 5th edition. Agent summary statements: toxin agents.Dec 2009 [internet publication].

BMJ talk medicine podcast: marine toxins poisoning, with Dr Jacob Lebin
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Natural Toxins in Food

What are Natural Toxins?

Natural toxins are toxic substances of natural origin produced by some types of living organisms. These toxins are not harmful to the organisms that produce them, but can be toxic to others, including humans, if taken with food.These chemicals have a variety of structures and differ in biological function and degree of toxicity.

Some toxins are produced by plants and act as a defense mechanism against predators, insects or microorganisms, or are formed as a result of damage to plants by microorganisms such as molds due to climatic stress (drought or extremely high humidity).

Other sources of natural toxins are microscopic algae and plankton that inhabit oceans and sometimes lakes and produce chemicals that are toxic to humans but not to fish or shellfish that feed on these organisms.In the case of human consumption of fish or shellfish containing these toxins, adverse reactions can quickly occur.

Below is a description of some of the most common natural toxins in food that pose a threat to our health.

Biotoxins produced by aquatic organisms

Toxins produced by sea and freshwater algae are called algal toxins. These toxins are produced by some algae species during the flowering period.Shellfish such as mussels, oysters, and scallops are more likely to contain these toxins than fish. Algal toxins can cause diarrhea, vomiting, tingling sensations in the limbs, paralysis and other effects in humans, other mammals and fish. They can accumulate in shellfish and fish, or contaminate drinking water. They are colorless and odorless and do not deteriorate during heat treatment or freezing.

Another example is ciguatera, or poisoning from eating fish contaminated with ciguatoxin, a substance produced by dinoflagellates, an aquatic single-celled organism.Ciguatoxin accumulates in fish such as barracuda, black grouper, dog snapper and king mackerel. Symptoms of ciguatera include nausea, vomiting, and neurological symptoms such as a tingling sensation in the fingers and toes. There is currently no cure for ciguatoxin poisoning.

Cyanogenic glycosides

Cyanogenic glycosides are phytotoxins (i.e. toxic compounds produced by plants) found in at least 2,000 plant species, many of which are consumed in some regions of the world.The most commonly consumed foods containing cyanogenic glycosides include cassava, sorghum, stone fruit kernels, bamboo roots, and almonds. The toxic potential of a cyanogenic plant depends mainly on how high the concentration of cyanide in the human body will be as a result of its consumption. In humans, acute cyanide intoxication can have the following clinical signs: increased breathing, drop in blood pressure, dizziness, headache, abdominal pain, vomiting, diarrhea, confusion, cyanosis, accompanied by fibrillar muscle contractions and convulsions, followed by a terminal coma.Death from cyanide poisoning can occur when they reach concentrations that exceed the metabolic capacity of a particular organism.


These toxins are produced by a variety of plants such as parsnips (a plant related to carrots and parsley), celery roots, citrus fruits (lemon, lime, grapefruit, bergamot) and some medicinal plants. Furanocoumarins are toxins produced by a plant in response to an irritant such as physical injury.In sensitive individuals, these toxins can cause gastrointestinal disturbances. Furanocoumarins are photosensitizing and can cause severe skin irritation when exposed to ultraviolet light. Most often, such reactions occur when the juice of these plants gets on the skin, however, cases of a similar effect have been described as a result of eating large amounts of vegetables rich in furanocoumarins.


Many beans contain toxins called lectins.They are most concentrated in beans, especially red beans. Just 4 or 5 raw beans can cause severe stomach pain, vomiting, and diarrhea. Lectins are destroyed by soaking dried beans for at least 12 hours and boiling them over high heat for at least 10 minutes. Canned beans have already undergone this processing and can be eaten ready-made.


Mycotoxins are naturally occurring toxic substances produced by some types of molds.Molds grow on a variety of foods such as cereals, dried fruits, nuts, and spices. Mold growth can occur both before and after harvest, during storage, and / or on finished food under conditions of favorable temperature and high humidity.

Most mycotoxins are chemically stable and are not destroyed during heat treatment. Mycotoxins present in food can cause acute intoxication, symptoms of which develop shortly after the consumption of highly contaminated food and can even be fatal.Chronic consumption of mycotoxins in food can have long-term negative effects on health, in particular, provoking cancer and immunodeficiency.

Solanin and Chakonin

All plants of the nightshade family, which include tomatoes, potatoes and eggplants, contain the natural toxins solanine and chaconin (glycoalkaloids). As a rule, the concentration of these substances in plants is low. However, they are present in higher concentrations in potato shoots and skins and greenish parts of its tubers with a bitter taste, as well as in green tomatoes.Plants produce a toxin in response to external stimuli such as mechanical damage, ultraviolet radiation, colonization by microorganisms, and attack from insect pests and herbivores. To prevent the formation of solanine and chaconin in potatoes, it is important to store the tubers in a dark, cool and dry place. It is also not recommended to eat the green or sprouting parts of the tubers.

Poisonous mushrooms

Wild mushrooms may contain a number of toxins, such as muscimol and muscarine, which can cause vomiting, diarrhea, confusion, visual impairment, increased salivation and hallucinations.Symptoms begin 6-24 hours after eating the mushrooms. Usually, fatal poisoning is characterized by the late development of severe symptoms characteristic of damage to the liver, kidneys and nervous system. Cleaning and heat treatment of mushrooms does not allow to eliminate the toxins contained in them. It is recommended to avoid eating any wild mushrooms in the absence of complete confidence in their harmlessness.

Pyrrolizidine alkaloids

Pyrrolizidine alkaloids (PA) are toxins produced by about 600 plants.Most of them are produced by plants of the families borage, aster and legumes. Many of these plants are agricultural weeds that infest food crops. PAs cause a wide range of negative effects. They can be acutely toxic. In this regard, the main source of concern is the ability of some PA to damage cell DNA, which can provoke cancer.

PA are not destroyed during heat treatment.They are found in herbs, honey, aromatic herbs and spices, and other foods such as cereals and cereals. However, the level of their consumption by humans is considered to be low. Due to the complexity of the issue and the large number of such compounds, the overall health risk has not yet been fully determined. The FAO / WHO Codex Committee on Contaminants in Food is developing recommendations to prevent PA-containing plants from entering the food chain.

What can I do to reduce the risk of natural toxins?

It is important to remember that natural toxins can be found in a variety of crops and foods. In a normal, balanced, healthy diet, the concentration of natural toxins is well below the acute and chronic toxicity thresholds.
To reduce the health risks associated with the presence of natural toxins in food, it is recommended:

• not to think that everything “natural” is harmless by definition;

• to dispose of damaged, wrinkled, discolored and, in particular, moldy food;

• throw away food that smells or tastes not fresh or tastes unusual;

• Eat only those mushrooms or wild plants that are definitely not poisonous.

WHO Activities

WHO, in collaboration with FAO, is responsible for assessing the risk of natural toxins to humans from food contamination and recommending the necessary protection.

Risk assessment for the presence of naturally occurring toxins in food is carried out by the FAO / WHO Expert Committee on Food Additives (JECFA) and is used by national governments and the Codex Alimentarius Commission (regulatory intergovernmental body on food standards) to determine the limit values ​​for various impurities in food or other risk management recommendations to prevent or reduce contamination.Codex standards provide an international benchmark for domestic food producers and food traders, and are designed to ensure that consumers around the world that the food they purchase meets established safety and quality standards, wherever they are produced.

JECFA sets maximum permissible levels for the consumption of various natural toxins.
JECFA or FAO / WHO ad hoc scientific expert groups are composed of independent international experts who provide scientific reviews of all published studies and other data on selected natural toxins.As a result of this health risk assessment exercise, either intake limits or other recommendations are formulated to indicate the degree of health hazard (eg exposure limits). Recommendations are made regarding risk management and measures to prevent and reduce contamination, as well as analytical methods and monitoring and control measures.
In order to avoid harm to human health, the content of natural toxins in food should be as low as possible.Natural toxins are not only a source of risk to human and animal health, but also negatively impact food security and nutritional status by limiting people’s access to healthy food. WHO strongly recommends that national authorities monitor the content of the most significant natural toxins in food products marketed in their markets and take measures to minimize it and ensure compliance with international guidelines on limit values, storage conditions and legislation.


STYLAB offers test systems for the determination of saxitoxin in shellfish and water by enzyme immunoassay, as well as standard saxitoxin solutions and standardized natural samples.

More about saxitoxin

Accessory kit for Saxitoxins (PSP) Shipboard Plate kit PN 530009 Saxitoxins (PSP) Shipboard
Accessory Pack

Saxitoxin ( PSP -toxin), also called paralytic poison (toxin) of shellfish and “factor of very rapid death”, has been studied better than other phycotoxins.It is a neuroparalytic poison with a potency comparable to that of tetrodotoxin. It is more than 100 times more toxic than hydrocyanic acid. Chemically, saxitoxin is an alkaloid.

Saxitoxin is produced by some dinoflagellates ( Alexandrium sp . , Gymnodinium sp . , Pyrodinium sp . , Cylindrospermopsis sp ., etc.). Dinoflagellates, or dinophytic algae, are unicellular organisms that are part of marine and freshwater plankton and benthos. The active reproduction of dinophytic algae is the cause of “red tides”. Cyanobacteria, including anabena and cylindrospermopsis, live in fresh water bodies. During the “bloom” caused by these organisms, the water is covered with a blue-green, blue or green layer of cyanobacteria. However, dinoflagellates and cyanobacteria do not always cause such noticeable blooms.More often, their detection requires analysis of water samples and targeted searches.

Aquatic organisms, such as molluscs, feed on dinoflagellates or cyanobacteria and accumulate their poisons, including saxitoxin. For invertebrates and fish, this poison is not as dangerous as for mammals, including humans.

Saxitoxin poisoning most often occurs after eating shellfish that have accumulated a sufficiently large amount of this substance. But the poison can also enter the body with water, and some authors argue about the possibility of contact poisoning with paralytic toxin of shellfish (contact of water containing this substance with the skin).

The mechanism of action of saxitoxin is the same as that of tetrodotoxin: both of these substances block the sodium channels of nerve cells. This leads to muscle paralysis and respiratory arrest. In case of milder PSP toxin poisoning, the victim’s lips or tongue become numb, ringing in the ears, a headache, and diarrhea begins.

It is believed that one of the first historical mentions of saxitoxin poisoning is dated July 8, 1799.According to the testimony of the head of the Russian-American trading company Alexander Baranov, on this day in Alaska on the shore of the Peril Strait between the islands of Sitka (Sitkha) and Chichagov from poisoning during 115 hunters died in two hours.The survivors hastily left the strait. This event was one of the reasons for the significant weakening of fisheries in Alaska over the next few years. This is how the traveler and writer Kirill Timofeevich Khlebnikov tells about him:

“The day after the party left Sitkha, they stopped in the Hutznov Strait. As usual, the Aleuts ate black shells and suddenly felt convulsions and nausea, from which more than 100 people died in the course of two hours. The leaders of the party, giving tobacco with gunpowder instead of emetic, managed to stop the infection, but in the course of time another 15 people died.Due to misfortune, this bay was called the Lost (Destructive) and is known so far ”.

Mussels, scallops and other edible bivalve molluscs that have accumulated this poison are most often caused by saxitoxin poisoning. In the tissues of mollusks, this poison lasts from 10 days to a year. Saxitoxin has also been found in the tissues of the blowfish family, which includes the brown puffer (puffer fish). A 2009 study in Brazil found that Nile tilapia, an edible freshwater fish that is bred in many countries, can accumulate saxitoxin.Therefore, it is necessary to analyze the content of saxitoxin in shellfish meat, fish, as well as in water.

In accordance with Unified sanitary-epidemiological and hygienic requirements for goods subject to sanitary-epidemiological supervision (control) and Technical Regulations of the Customs Union TR TS 021/2011 food safety , The content of saxitoxin in molluscs should not exceed 800 μg / kg.For the latest statutory regulations please visit compact24.com . The same norm is adopted in the EU countries and in the USA. However, in the United States, it also applies to freshwater and marine fish, crustaceans and other aquatic animals with the exception of birds and mammals. According to some sources, saxitoxin poisoning is also possible when eating shellfish containing this substance within the specified limits.

For the analysis of saxitoxin and related substances in food products, the HPLC method is usually used in accordance with GOST EN 14526-2015 “Food products.Determination of saxitoxin and DC-saxitoxin in mussels. HPLC method using pre-column derivatization by peroxide or periodate oxidation. “An HPLC method that allows the quantitative determination of toxins in a sample. This method can only be performed in a properly equipped laboratory. In addition, it requires the use of standards . Alternative him – the method of enzyme-linked immunosorbent assay (ELISA), which has high sensitivity and accuracy, as well as easy to use.


  1. Konovalova N.V., Mogilnikova T.A. Toxic phytoplankton and biotoxin content in scallop tissues. Basic research No. 9 2006
  2. Benford Diane J., Eskola Mari, van Leeuwen Rolaf. European risk assessments of marine biotoxins. On behalf of the biotoxin working group of the EFSA Panel on Contaminants in the Food Chain (CONTAM) ICMSS09 – Nantes, France – June 2009
  3. DeGrasse, S., et al., Onboard screening dockside testing as a new means of managing paralytic shellfish poisoning risks in federally closed waters.Deep-Sea Res. II (2013)
  4. J.A. Galvao et al. Saxitoxins accumulation by freshwater tilapia (Oreochromis niloticus) for human consumption. Toxicon 54 (2009) 891–894

90,000 Shellfish from the coast of Primorye can be poisonous to humans PHOTO

07/12/2010 – 09:33 573 views


Scientists have found toxins released by algae in mollusks caught off the coast of Primorye, which can cause poisoning in humans, Tatyana Orlova, candidate of biological sciences, employee of the Institute of Marine Biology (IBM) of the Far Eastern Branch of the Russian Academy of Sciences, told RIA Novosti on Monday.

These data were obtained in the course of a large-scale experiment carried out by specialists of the Center for Monitoring Harmful Microalgae and Biotoxicity of Coastal Marine Areas of the Seas of the Far East of the Russian Federation, operating on the basis of the IBM FEB RAS.

During the year, specialists selected and studied the toxicity of molluscs, mainly mussels caught in the Amur Bay. A diarrheal toxin has been found in mussels, which can cause symptoms of an acute intestinal infection in a person who has eaten the shellfish, she said.

The data obtained during the experiment confirmed that the microalgae inhabiting the Amur Bay are poisonous. According to scientists, toxin contamination of shellfish is caused by microalgae blooms. The concentration of the toxin varied, but always exceeded the maximum permissible by 1.2-3 times. The peak of pollution was in June, it is at the beginning of summer that microalgae that release toxin begin to develop rapidly.

“Molluscs – mussels, scallops, oysters – are capable of accumulating microalgae toxins.For molluscs, the accumulation of toxins is not dangerous, and if a person eats such a mussel or scallop, he can get food poisoning, “Orlova explained.

Toxic hot flashes caused by microalgae blooms are often impossible to see with the naked eye, she said. Microalgae are capable of releasing several types of toxins. including paralytic, amnesic, neurotoxic, diarrheal. “Traces of amnesic toxins were also found in mollusks taken in the Amur Bay. But they do not exceed the maximum permissible concentration, “she said.

“For example, earlier off the coast of Kamchatka, a bloom of microalgae causing paralytic poisoning was recorded. Fatal cases were noted, they were documented,” she added. There are no antidotes for poisoning with microalgae toxins, you can only provide help, as with ordinary poisoning, she added. The severity of the poisoning depends on the dose, the general condition of the human body.

The development of toxic microalgae is to a small extent related to anthropogenic impact.Even where the water is clear, these dangerous algae live, added the agency’s interlocutor.

Processing – neither boiling, drying or freezing – is not capable of destroying the toxins accumulated in shellfish, she said. Now, with the onset of summer, lovers of eating mussels and scallops caught in the Amur Bay should be especially careful, she added.

RIA Novosti

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“Poisoned Kamchatka”. How they are looking and why they cannot find the source of ocean contamination

  • Olga Shamina
  • BBC Russian Service

Photo by Yelena Vereshchaka \ TASS \ Getty Images

There are several in Kamchatka The search continues for weeks for an unknown substance that has poisoned dozens of people and caused the death of thousands of marine animals.Now the version about poisoning with a natural toxin, a product of microalgae bloom, has come to the fore, but this is still not the final conclusion. How scientists, ecologists and ordinary people are looking for a source of large-scale contamination of the ocean and why they have not been able to find it for so long, the BBC Russian Service figured out.

On October 8, the giant Khalaktyrsky beach is almost empty. A tall man in a wetsuit and a surfboard is walking along the black sand to the ocean. A whole procession follows him.

Ahead – several journalists who ask a man if he is afraid to go into the water.He ignores them. The journalists are followed by a group of local surfers led by Anton Morozov, the first surfer in Kamchatka who has been skating here for about 15 years. My student, proudly nods at the man Morozov.

Some of the surfers say that this person’s name is Ramil and in ordinary life he is a high-ranking official of Rosprirodnadzor. Ramil poses with a blackboard on the shore for some time, answers journalists’ questions in monosyllables and emphasizes that he came here as a “civilian”.Then he climbs into the water.

The waves are too strong, Ramil cannot stand on the board for a long time, so he returns to the shore to rest and warm up. “Feels good, the water is salty, yes! Average good, I smell the smell. Frequent waves, surf, it’s hard to get out, I’m not such a surfer, not a master,” he complains in a conversation with the BBC. Then he enters the ocean again.

Photo caption,

Surfer Ramil is going to stand on the board on Khalaktyrsky beach

The next day the same surfers are going to be examined at the regional hospital.They themselves have not skated for a long time: in mid-September they started having eye problems, then many had a fever and symptoms of poisoning.

At the hospital, surfers pass each other a phone with a local media report that the deputy head of Rosprirodnadzor Svetlana Radionova was injured while surfing on Khalaktyrsky beach – he now also has eye problems.

Radionova really has a deputy named Ramil Nizamov. The Russian service of the BBC did not find his contacts in the public domain.

On the same day, October 8, Radionova herself held an impromptu press conference on the ocean shore, telling reporters how her department daily takes samples in the bays and rivers of Kamchatka, trying to establish the source of pollution that led to the poisoning of people and the mass death of marine animals.

Not only Rosprirodnadzor is trying to find the source of infection. Ecologists, journalists, officials have come to Kamchatka, water and soil samples are being studied at the local and federal levels.Greenpeace is conducting its own investigation. Scientists organize expeditions almost every other day to understand the scale of the infection. The Governor holds daily meetings and reports on what is happening on social networks.

Almost a month has passed since the moment when Kamchatka surfers began to complain of pain in their eyes, two weeks – since the dead ocean inhabitants thrown out by waves began to be found on local beaches. But until now, the reason why the water has become dangerous for people and animals has not been finally named, and the scale of the infection is not clear.

Photo caption,

Rosprirodnadzor holds a press conference on the ocean coast

All estimates of possible damage are based on several dives by divers and divers at various points in Avacha Bay, as well as on the study of a small area of ​​the bottom near Petropavlovsk-Kamchatsky using an underwater drone.

Kamchatka authorities advise the inhabitants of the peninsula not to go into the water yet, but it is better not even to approach the ocean.

People are still sick

For the most part, the locals themselves do not strive to go to the ocean, although there are exceptions.Anton Lankin is engaged in the tourism business in Kamchatka: he has a diving club. Already in early October, he sailed along the local bays on a boat with several journalists.

“We went to Grotovaya, to Bezymyannaya Bay. The weather was very heavy, the wind was strong. We were just poured with water,” he says. Anton is noticeably distinguished from those around him by his bright red sore eyes.

Photo caption,

Anton Lankin drove journalists around the bays and, according to him, injured his eyes. They got water from the ocean

A man in a black sports jacket sits on a hospital bench next to Lankin.He lifts her sleeves to show the BBC correspondent the traces of healing burns. Then he pulls out his phone and shows pictures of hands with bright pink spots on the wrists. The man’s name is Yuri Kretov, he says that a week ago he was fishing in Malaya Lagernaya Bay.

“Literally two hours after contact with water, there was a strong burning sensation in the hands. I was wearing protective gloves, took off my gloves, saw irritation as if smeared with acid. I stopped contacting, came home, blisters swelled,” recalls Yuri.

He says that his hands were treated at the emergency room, diagnosed with a chemical burn to both hands. Yuri came to the hospital to be checked and tested – suddenly the poisoning will have some long-term consequences.

A man shows burns on his hands

A man shows burns on his hands

“The number of [hits] is increasing daily.Now we have 16 people, and of them there are three children. These are those who walked along the shore or were on boats, “Acting Minister of Health of the Territory Marina Volkova told the BBC on October 9.

” Everyone has their own symptoms. Someone has objectively no symptoms, someone has conjunctivitis or a mild, first-degree corneal burn. All medical care is provided to them, “she says.

Surfers who began to get sick in September complained of massive poisoning and fever.Volkova says that only they had such symptoms and were no longer detected.

“There was a perspiration in my throat, there was a very strange taste, I don’t know what it was like, I have never seen this in my life. I clearly gave off iron, some kind of chemistry. Then my hands began to itch, there was some kind of rash,” recalls the surfer and the founder of the Snowave school Anton Morozov.

Photo caption,

Surfer Anton Morozov was forced to close the Snowave school ahead of time due to environmental problems

According to him, people living in the camp on the shore of the Khalaktyr Bay and in neighboring camps started vomiting in mid-September and appeared temperature.And problems with the eyes and throat then showed up even in those who did not ride the waves.

According to Morozov, there were about 200 people in their camp alone – not all were injured, but at least fifty developed certain symptoms.

Snowave administrator Ekaterina Dyba told the BBC that one of the first in the camp to get sick was a five-year-old girl who did not even go into the ocean. Dyba herself had symptoms of poisoning and fever. She recalls that almost everyone who constantly worked in the camp was sick.

At the first stage, few went to the doctors, says Dyba: many initially did not correlate their symptoms with a possible infection from water. In addition, there is no paved road to the camp, not all local drivers are ready to go there, besides, people did not want to go to the hospital amid the coronavirus epidemic.

The BBC’s interlocutor, close to the local health ministry and not authorized to speak to the media, claims that doctors and toxicologists have arrived from Moscow and are now checking the victims, including surfers.But it is almost impossible to detect toxins in them, since they arrived at the hospitals too late. Therefore, recently sick people, like Lankin and Kretov, are of particular interest to doctors.

“We do not know that at great depths”

“There are ascidians, they are as beautiful as underwater flowers, tall. And now they are shriveled, ugly”, – scientist Sergey Korostelev points to the gray mass that lies between dead starfish and the remains of sea urchins on the central embankment of Petropavlovsk-Kamchatsky.

Korostelev works at the World Wildlife Fund (WWF) as the coordinator of the sustainable marine fisheries program. He has been living in Petropavlovsk-Kamchatsky for 25 years, but this is the first time he has seen such a number of dead animals thrown ashore.

Photo caption,

Starfish and urchins became one of the main victims of the poisoning

On the central embankment of the city, they lie in layers, becoming prey for dogs and birds (while there is no mass death of birds or dogs in the city), entertainment for local children and the subject of study – for scientists and ecologists.

Scientists and Greenpeace representatives are looking for the largest and best-preserved dead sea animals on the beaches. The finds are put in bags and sent for analysis to Moscow, St. Petersburg or Vladivostok, where laboratories will try to find out which toxin killed them.

From the remains of marine animals, an indirect conclusion can be drawn about how badly the ocean was damaged. Now on the beaches they find mainly animals that live at a depth of up to 20 meters.”We do not know what is happening at great depths. This information is difficult to collect, special research is needed,” explains Korostelev.

A few minutes later he finds the remains of a snow crab – this crab usually lives deeper than the rest of the discarded animals. “These are most likely juveniles that could have got into this 20-meter zone,” the scientist says, but admits that this could be a sign of a larger, deeper damage to the ocean.

Photo caption,

Deep-sea snow crabs can also be found on the shore

Governor of Kamchatka Vladimir Solodov in a conversation with the BBC admitted that the study of the bottom at a depth of more than 20 meters has not yet been carried out, what is happening there – he does not yet know no one.

On October 5, an expedition of employees of the local Kronotsky Nature Reserve and a number of institutes went to sea to study the bottom of the Avacha Bay. The divers made dives at four points south of Cape Nalychev at a depth of 10-15 meters, then reporting the death of 95% of all benthos – living organisms that live on the bottom – in places of immersion.

How massive the death of benthos was is not yet clear. Diver Sergey Klepas in early October dived in Salvation Bay in the place where he used to catch sea urchins, and did not find a single living one.”All dead completely, took out a dead octopus,” he says.

But on October 9, local scientists, together with Vasily Yablokov from Greenpeace and an employee of the Investigative Committee, made six more dives in the northern part of Nalychev Cape and at three points around Krasheninnikov Island and mostly found live benthos.

“There was no mass death of benthic organisms,” says the report, which the BBC has. True, scientists cannot answer the question of whether there are fewer of these organisms, because background studies in these places have not been carried out before.

Head of the scientific department of the FSBI “Kronotsky State Reserve” Daria Panicheva, who took part in both expeditions, told the BBC that there was no “cemetery” of animals at the bottom of the ocean in the north of the bay, although she did not rule out that the remains could already take it ashore. But she says that living organisms were not the same as usual: many were not attached to the bottom of the ocean, and the needles of the hedgehogs began to fall off.

From 11 to 13 October, a group of scientists, which included the Kronotsky Reserve and Greenpeace, made an expedition to the south of the peninsula.There they also found dead bottom organisms, but at the same time living and apparently healthy mammals – sea lions, sea otters, seal seals and gray whales. According to a report available to the BBC, they caught live fish at several locations.

Scientists say that benthos has become the main victim of as yet unknown toxins. “Those organisms that could not get out, could not escape from this pollution, that is, those that are attached and those who move slowly,” explains Vasily Yablokov.

Photo author, Yelena Vereshchaka \ TASS \ Getty Images

Photo caption,

Greenpeace and local ecologists check local rivers, lakes and other bodies of water

Benthos losses will still hit the entire food chain, explains Korostelev.For example, sea otters feed on hedgehogs and molluscs, and even if they are not poisoned by them, there will be less food for sea otters.

If the dead animals can be poisoned, that is, the toxin accumulates in the food chain, the consequences can be much more serious. However, it is necessary to wait for certainty as to what kind of substance it is, the ecologist stipulates.

It is because of the destruction of part of the food chains that Greenpeace calls the situation in Kamchatka an “ecological disaster”.

How environmentalists are investigating the disaster

“When we arrived here, we thought that we would find this source with our own eyes, or together with government agencies, or somehow. But while we are here, the situation does not become clearer,” says Vasily Yablokov, who together with his colleagues arrived in Kamchatka in early October. At the time of the conversation with the BBC, five Greenpeace employees were working on the peninsula, they were assisted remotely by the Moscow office.

According to him, Greenpeace ecologists for a week on the peninsula examined many different places, including rivers and landfills, took samples, interviewed local residents.”We paid attention to all the details. And we cannot make any unambiguous conclusion that there have been some serious changes on land that could lead to such a situation in the ocean,” says Yablokov.

On Wednesday October 14, Greenpeace reported interim results. Many different substances were found in the samples taken – from oil products to substances that can be included in the composition of biopesticides. But none of these substances in the detected concentration could lead to such consequences.

Photo author, Dmitry Sharomov / Greenpeace


Greenpeace is trying to indirectly check if there are any leaks from military training grounds using samples from rivers

Yablokov says that pollution was observed 70 km from Khalaktyr beach – apparently , the infected spot does not dissolve in the ocean. To cause such damage to the ocean, the land leak would have to be “massive,” he explains. And ecologists do not see such large-scale pollution on land.

“Every day it is as if we are approaching somewhere, but very, very slowly,” the ecologist believes.The investigation is not going as fast as it is shown in movies or TV shows, where scientists using the latest technology almost instantly get an answer to any question, scientists explain.

The whole process takes a lot of time: you need to collect samples, pack them, send them by plane to Moscow or Vladivostok. There, analysis in laboratories can also take weeks, the sample itself may not fit, and the scientists’ initial hypothesis may not be confirmed.

In addition to Greenpeace, local environmentalists are also investigating.A scientific headquarters for the ecological safety of the region was created in Kamchatka, headed by the director of the Institute of Volcanology and Seismology of the Far Eastern Branch of the Russian Academy of Sciences Alexei Ozerov.

Governor of Kamchatka Vladimir Solodov is also actively involved in the investigation and holds meetings on the situation almost every day. In an interview with the BBC, he said that he had invited foreign experts to participate in the investigation.

Solodov was appointed as interim governor in April this year by President Vladimir Putin.In September, he went to the polls as a self-nominated candidate. It was during elections in the region that surfers began to get sick, and just a few days after the new governor took office, there were reports of animals washed ashore.

Yablokov and other environmentalists say that the regional government and Solodov do not interfere with their investigation, they are even trying to help in every possible way. “There are no obstacles to our activities, we travel freely wherever it is allowed, of course,” he says.

Photo caption,

There are several large military bases and training grounds in Kamchatka, where the civilian population simply cannot get to

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The reservation concerns military facilities, which are numerous in Kamchatka.Often on the roads you can see signs “Forbidden zone” or “Stop, shoot”. There are also abandoned military towns and units near the existing facilities.

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Kamchatka is a border region, next to which Japan and the United States are located. There are many military facilities on the peninsula – primarily the Pacific Fleet (Pacific Fleet), air defense forces, military space forces and border troops.
On the opposite side of the Avacha Bay from Petropavlovsk-Kamchatsky, the main base of nuclear submarines of the Pacific Fleet, Vilyuchinsk, is located.Nearby are the coastal support units of the Pacific Fleet and the shipyard of the Russian Navy.
Another large facility is the large airbase at Yelizovo airport, which houses, in particular, the naval aviation of the Pacific Fleet and fighter-interceptors. Like the submarine base, the Elizovo airfield is located just a couple of tens of kilometers from Petropavlovsk-Kamchatsky. The 40th Marine Brigade is stationed in the city itself.
Not far from the city there is a divisional training ground, which is called Radyginsky or Wet sands.It is also located about a couple of tens of kilometers from the city, on the very shore. One edge of the polygon just goes to the Khalaktyrsky beach.
This test site is a desert plateau, pitted with craters from shells and missiles – they are clearly visible even on satellite maps on the Internet. There is a small garrison with barracks at the range, in which military men usually live, who come to the shooting. Before the shooting, the regional administration publishes a warning with the coordinates of the boundaries of the area, into which it is dangerous to enter.
To the north, in the area of ​​the Klyuchi settlement on the eastern coast of Kamchatka, there is another, very large polygon. This is “Kura” – a huge target at which strategic troops are firing missiles. There are several military units on the Kura, the main task of which is to record the result of hitting by training warheads.

End of inquiry about Kamchatka

“Often these are classified objects, what is there – no one knows,” explains Yablokov. Greenpeace, according to him, made a request to the Ministry of Defense.“We can only believe – they said that everything is normal at their facilities,” says the ecologist.

Governor Solodov in an interview with the BBC says the same thing: the Ministry of Defense independently conducts a separate inspection of its facilities. General civil structures, such as Rosprirodnadzor or Rospotrebnadzor, are not allowed there. When asked by the BBC about whether there are chemical weapons on the peninsula, the leakage of which could cause such consequences, the governor replied that such topics were not within his competence.

Solodov speaks of the need to create a unified monitoring system for the environmental situation in the region, which will make it possible to obtain data on the territories occupied by the Ministry of Defense.

Military-related environmental incidents have occurred on the peninsula before. Local residents recall how metal barrels were found on Khalaktyr Beach in September 2014: judging by the markings, they could contain napalm components.This happened after the next exercises with the amphibious assault landing.

After this incident, the military organized a “general cleaning” of the territories in which they were conducting exercises.

Landfills and garbage dumps

But it is not only the military that litter the Kamchatka nature: dead animals on the central beach of Petropavlovsk-Kamchatsky lie among a variety of garbage. The city itself and even the surrounding forest are littered with car tires.“I have never seen anything like this anywhere in Russia and in the world,” Governor Solodov admits in a conversation with the BBC.

Alexey Ozerov, in an interview with the “Editors” said that around Petropavlovsk-Kamchatsky there are at least five landfills with various wastes. Environmentalists spoken to by the BBC confirm these numbers.

According to the report of the scientific headquarters, following the meeting of the crisis commission on October 10, scientists identified the main objects that, in theory, could become a source of ocean pollution:

• Polygon Kozelsky

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In the early days after dead animals were found on Kamchatka’s beaches, the most popular version among local residents was the waste leak from the Kozelsky landfill.Many of them still believe in it.
“Kozelsky” is not even a full-fledged landfill, but just a dump of pesticides, which was arranged by the company “Kamchatselhozsnab” in the late 1970s. “They just buried it in the ground and left. After that, when it was discovered, a complex of protective measures was carried out, ”Governor Solodov describes the history of the landfill in an interview with the BBC.
The landfill is now a field, not fenced off by any kind of fence. There is only a sign “Caution, toxic chemicals” and iron pillars instead of gates.From Petropavlovsk-Kamchatsky to the landfill – about an hour along a country road. Anyone can get to the landfill, for this you only need a car with a high landing. The polygon is separated from the forest by two moats. In the inside, a black film is visible, which in some places comes out of the ground.
The Mutnushka River flows near the landfill. It flows into the Nalycheva River, which in turn flows into the ocean. Greenpeace initially said that the water in the river was visually polluted, but in the end, none of the environmentalists found there a high concentration of any toxic substances.The local scientific headquarters found various living organisms in the river and recognized the water in it as complying with GOST “drinking water”.
The authorities have already announced plans to reclaim the Kozelsky landfill.

End of information about Kozelsky

• Polygon Radyginsky

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The landfill is located on the way from Petropavlovsk-Kamchatsky to the Kozelsky landfill. There are several abandoned military buildings near it. Not far from the landfill are the village of Radygino, the Nalycheva river and the Khalaktyrsky beach.For example, naval ships are shooting from the ocean at the range.
The newspaper “Rybak Kamchatka” reported in 2000 that rocket fuel and melange oxidizer may be at the test site. After the disbandment of the local anti-aircraft missile unit, according to the newspaper, a poisonous dump was formed at the test site.
Greenpeace sent a request to the Ministry of Defense about the landfill, and also made water samples from the surrounding rivers and analyzed satellite images of the territory, says Yablokov. A significant leak of harmful substances should be clearly visible, but so far environmentalists have not found traces of it.The local scientific headquarters said that no traces of heptyl (a component of rocket fuel) were found in Avacha Bay. Greenpeace also found no such traces.

End of information about Radyginsky

• Lake Tidal

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Another potential source of leakage may be Lake Prilivnoe, located east of Petropavlovsk-Kamchatsky. Next to it is the Babiya Bay, not so far away is the Khalaktyrsky Beach.According to the report of the scientific headquarters, for many years there was a dumping ground for garbage and various waste.
“This is an old, old landfill for household waste,” says local ecologist and teacher Arina Shurygina. Ten years ago, she said, scientists recorded in streams and springs near the lake exceeding the permissible concentrations of phosphates and nitrates.
“This lake is called Tidal for a reason. It periodically closes with storms, ”she explains. It is possible that the landfill is sometimes flooded. Theoretically, in this way, a “salvo concentration” of some accumulated harmful substances from the landfill can go into the ocean, Shurygina believes.
After news of ocean contamination, she took water samples from the lake, but no results yet. Shurygina says that she saw live fish and crustaceans in Tidal, and believes that now there is no problem with water there.

End of Help o Tidal

The report also includes wastewater from Petropavlovsk-Kamchatsky, Elizovo and the closed city of Vilyuchinsk. Local residents in conversations with the BBC talk about possible emissions from the ocean, for example, from a submarine or from ships buried at the bottom.According to Governor Solodov, 84 ships were sunk in the Avacha Bay only according to official data in previous years.

But the versions of sewage, the release of toxic substances from sunken ships or passing submarines have not yet been confirmed by analyzes.

Another argument against them is the amount of ocean pollution. Animals died in the coastal zone for several tens of kilometers. Judging by the contamination of people, the contamination is still present.Such large-scale contamination would be easy to detect if it was a leak of some understandable substance like heptyl. But neither local scientists nor Greenpeace found it.

Photo caption,

At the bottom of the bay near Petropavlovsk-Kamchatsky, according to scientists, there are almost no living organisms left

Algae after all?

There is still no final conclusion on the causes of the ecological disaster, but both local scientists and Greenpeace experts are gradually moving away from the version of the technogenic contamination of the ocean from the shore.The version about toxic algae is being heard more and more often.

Governor Solodov told the BBC that initially he himself did not take this version seriously. He says that some biological toxins have already been identified, and microalgae have also been found capable of producing them.

But so far, only one toxin has been identified that can cause intestinal poisoning and the death of mollusks – okadaic acid, which is formed during the flowering of certain types of algae.

“There was flowering, toxins were found, but these toxins are in small concentrations,” Pavel Dmitrenok, director of the Pacific Institute of Bioorganic Chemistry, said at a press conference on October 12.Scientists have not yet found other toxins.

Scientists have identified okadaic acid methyl ester in a water sample in Zhirovaya Bay, but the concentration was far from the maximum allowable. They found the same toxin in the samples of dead animals – in three mussels found on the Khalaktyr beach.

Photo caption,

Some ecologists claim that the yellow foam seen by surfers and local residents is not a toxin, but its consequence, the remains of living organisms

Dmitrienok specified that scientists will continue to look for the toxin.He admitted that the cause of the pollution could be a substance that, in principle, is not known to scientists.

The report of the scientific headquarters also says that scientists will now try to determine what kind of algae they were, as well as whether they are typical representatives in these places or were transferred here from some other territories.

Earlier, the head of the scientific headquarters Alexei Ozerov said at a meeting of the commission that toxic algae came out on top among other versions.

Earlier in Kamchatka, “red tides” were already recorded, which were associated with the release of biological toxins.Moreover, earlier because of them, the death of fish was noted, but such a large-scale death of marine organisms was not observed.

Greenpeace does not rule out the algae version either, but is working on others as well. The appearance of algae can be associated with many reasons, for example, global climate change, explains Yablokov.

Photo caption,

Vasily Yablokov lived in Kamchatka for some time, and in 2020 he came here to look for toxins that led to the death of animals

Another possible reason is water pollution with chemicals that enter it in small concentrations and lead to algal blooms.

One of the environmentalists, who is not authorized to comment on the media, says that he “would very much like this version to be confirmed.” Although the same version looks the safest for the official authorities, since it excludes conflicts, for example, with the Ministry of Defense or other structures that could be to blame for the emissions.

“Some people say, well, thank God, it’s natural,” says Arina Shurygina. But this, in her opinion, is much worse than any version with heptyl or other substances – in this case, one could simply find the culprit and clean up the territory, but the reproduction of toxic algae may be evidence of much greater environmental problems in the region.

“This means that something has changed a lot in the world, and we need to apply different requirements to ourselves,” she says.

“This kills everything”

“It will be awesome, we will exhale if it is algae,” Anton Morozov believes.

He and other surfers like the natural version of the disaster better – the contamination of Kamchatka with man-made waste can scare away tourists from the peninsula.

Photo caption,

Surfers left the camps on Khalaktyr beach at the end of September, leaving many unprepared for winter

In recent years, the surfer camp on Khalaktyr beach has grown greatly: in addition to the Snowave camp itself, new surf schools, a tourist center and campgrounds have appeared.In September, the Pacific Ocean Jazz Festival was held on Khalkatyr Beach, which the organizers plan to make annually.

A five-star hotel with a spa center is being built in Petropavlovsk-Kamchatsky itself. In early October, Deputy Prime Minister Marat Khusnullin visited the region. Among other things, he was presented with the project of a new airport.

But the environmental crisis threatens to finish off the tourism sector, which is so badly affected by the pandemic.

“It kills everything!” – Anton Lankin, the owner of the diving club, is noticeably nervous.He has several boats, and the tourist season for him lasts until mid-October. “We show people the beauty of our land. We are simply deprived of this. The tourists themselves will not go here, they understand everything. Poisoned Kamchatka,” says Lankin.

Photo caption,

The surfer camp was built in the tundra, where rare plants grow. Environmentalists fear that tourists will trample them

Snowave and neighboring surfer camps were forced to close about a month before the end of the season.“This is our only income – and in general, our whole life is connected only with this,” says Morozov, who cannot yet assess the possible financial losses.

“I was born here, this is my home. I live on the ocean. This is the whole meaning of life, we promote surfing, we promote the region. People flew here from all over the world before the situation with the virus,” says Morozov. “And we are proud of this place and country too, well, really, we are all drowning for Russia. We even have traditions, when a person rides along a wave for the first time, we all shout: Russia! “

With the participation of Maria Kiseleva and Pavel Aksenov

Photos by Evgeny Zhuravlev and Maria Kiseleva.

Map – Anastasia Napalkova and Olesya Volkova

Scientists: Primorye molluscs can cause poisoning with accumulated toxins – Archive

These data were obtained during a large-scale experiment carried out by specialists of the Center for Monitoring Harmful Microalgae and Biotoxicity of Coastal Marine Areas of the Russian Federation operating on the basis of the IBM FEB RAS.

During the year, specialists selected and studied the toxicity of molluscs, mainly mussels caught in the Amur Bay. A diarrheal toxin has been found in mussels, which can cause symptoms of an acute intestinal infection in a person who has eaten the shellfish, she said.

The data obtained during the experiment confirmed that the microalgae inhabiting the Amur Bay are poisonous. According to scientists, toxin contamination of shellfish is caused by microalgae blooms. The concentration of the toxin varied, but always exceeded the maximum permissible by 1.2-3 times.The peak of pollution was in June, it is at the beginning of summer that microalgae that release toxin begin to develop rapidly.

“Molluscs – mussels, scallops, oysters – are capable of accumulating toxins of microalgae. For mollusks, the accumulation of toxins is not dangerous, and if a person eats such a mussel or scallop, he can get food poisoning,” Orlova explained.

Toxic flushes caused by microalgae blooms are often impossible to see with the naked eye, she said. Microalgae are capable of releasing several types of toxins, including paralytic, amnesic, neurotoxic, diarrheal.”Traces of amnesic toxins were also found in the mollusks taken in the Amur Bay. But they do not exceed the maximum permissible concentration,” she said.

“For example, earlier off the coast of Kamchatka, a bloom of microalgae causing paralytic poisoning was recorded. Fatal cases were noted, they were documented,” she added. There are no antidotes for poisoning with microalgae toxins, you can only provide help, as with ordinary poisoning, she added. The severity of the poisoning depends on the dose, the general condition of the human body.

The development of toxic microalgae is to a small extent related to anthropogenic impact. Even where the water is clear, these dangerous algae live, added the agency’s interlocutor.

Processing – neither boiling, nor drying or freezing – is not capable of destroying the toxins accumulated in shellfish, she said. Now, with the onset of summer, lovers of eating mussels and scallops caught in the Amur Bay should be especially careful, she added.

Shellfish | RuDIVE Group

Molluscs are an amazingly diverse type of invertebrates.Human life is inextricably linked with them, since most of the seafood we eat is a variety of shellfish and fish that feed on them. In addition, there are creatures among them that can cause a lot of trouble for an unwary diver.
The body of the molluscs is divided into three sections: head, trunk and leg. In different classes and orders of soft-bodied in the process of evolution, all sorts of modifications of these sections occur: for example, in cephalopods, the leg has turned into eight or ten tentacles, in pterygopods – into a pair of wing-like lobes; in bivalves, the head has practically disappeared, while in octopuses it contains a brain comparable in complexity to the brain of great apes.In some mollusks, the characteristic outgrowth of the body – the mantle – grows, enveloping the entire body, and forms an internal mantle cavity. The product of the excretory activity of the mantle is a calcareous multilayer shell, spirally twisted, bivalve, cap-shaped, lamellar, or rod-shaped. The shell is one of the main distinguishing features of the type, by which even a child can easily identify a mollusk.
According to the structure of the body and other characteristics, mollusks are divided into classes. Three of them are of interest to divers:

  • gastropods,
  • double doors,
  • cephalopods.


Gastropods, with some exceptions, have a spirally twisted or cap-shaped shell, in which the body with internal organs is hidden, exposing only the head and muscular plantar leg during movement. At the moment of danger, the mollusk first removes its head, then its leg into the shell, and covers the entrance with a dense chitinous lid. On the head is a gluttonous mouth leading to the throat with a radula – a special mouth apparatus resembling a grater.The classic radula consists of several rows of denticles, with which the mollusk scrapes the living organic layer from the surface of the substrate. In carnivorous gastropods, the radula has changed, and innocent teeth have turned into grasping jaws and teeth. In the pharynx, the ducts of the salivary glands open, whose secret is poisonous in some species.

Coral reefs are home to unusually beautiful gastropods – cones (family Conidae). Their conical shiny shell with a bizarre variegated pattern is an expensive and desirable exhibit in any conchological collection.Especially prized are the shells of the conus textile and the sea glory cone (C. gloria-maris), which are also among the seven most dangerous species.
Cones are voracious nocturnal predators. They hunt actively, crawling in search of prey on coral sand or along the reef itself. The head is equipped with a sensitive siphon, a pair of tactile tentacles, and a pair of eyes. A flexible muscular proboscis is clearly visible between the tentacles. At the moment of the attack, he sharply moves forward and hits the victim with a poisonous tooth sitting at its end.Rather, it is not even a tooth, but an arrow, which, having pierced the victim’s body, remains there. The venom of the cones is highly toxic: one injection is enough to paralyze small fish or invertebrates. The behavior of different types of cones is different: some are timid and hide in a shell at the slightest danger, others, such as textile and marble cones, are very aggressive. If disturbed, they throw out the proboscis and “shoot” from it with their deadly arrows.

Poison Arrow is a modified hypertrophied denticle of the radula, which really looks like an arrow with a tip and connective tissue “plumage”.The very same radula is transformed into the so-called scabbard with many radular teeth, or arrows. The bag-like “scabbard” opens into the lumen of the pharynx. The duct of the poisonous gland, located at the back wall of the body, opens next to it. Until now, the mechanism of the flow of arrows from the scabbard into the tip of the proboscis is not entirely clear, but it seems that the layer of ciliary epithelium plays the main role in this amazing process. The coordinated work of the cilia drives the arrow down the throat into the proboscis, and along the way it is charged with poison.Then the arrow is in the hole of the proboscis, which is ready to drive it into the victim’s body with a powerful muscular effort.

Sometimes the victims of the cones are divers who, out of curiosity or greed, have taken a beautiful shiny shell in their hands. A cone prick does not cause severe pain; victims compare it to a wasp sting. But soon the toxins that got into the blood begin their destructive effect. Symptoms of poisoning appear: spreading edema, nausea, shortness of breath, visual disturbances, impaired coordination up to paralysis of the respiratory muscles.Therefore, people around should be ready to provide first aid to the victim. 25% of the reported cases of cone injections were fatal – in other words, one in four who were stung by a cone died! The following species are deadly for humans: C. textile, C. geographus, C. striatus, C. aulicus. Some species, although not the cause of the documented fatal injections, are very aggressive, poisonous and potentially life-threatening: C. tulipa, C. marmoreus, C. gloria-maris, C.lividis, C. omaria, C. pulicarius, C. sponsalis, C. Imperialis.

Since even experts do not always at first glance determine the species of the cones, they should be handled with care. Sometimes it is very difficult to resist the temptation to take a shell in your hands and take a closer look at the bizarre patterns on it, especially when the shellfish hid in the shell and closed the lid on its leg. Be careful! If the mollusk has relaxed and looked out of the shelter, showing the tip of the proboscis, immediately throw the shell, otherwise it will be too late.

Nudibranchs are one of the most beautiful marine life. Instead of the spirally twisted shell typical for gastropods, bright and lush branchy processes bloom on their dorsal side – hepato-gill outgrowths, which, being a distinctive feature of these mollusks, gave the name to the entire group.

Nudibranchs feed on creepers: anemones, hydroids, and the amusing floating mollusks Glaucus marinas – even on jellyfish and siphonophores. They bite off and swallow pieces of eaters, and the nematocysts are not digested, but transported to the hepato-gill outgrowths on the back, where they are embedded in the epithelium of the nudibranch and serve as an excellent defense against predators.Stinging cells retain their “lethal” force for a long time, so it is better not to touch these gastropods. Touching the nudibranch, which ate a Portuguese boat for breakfast, can get the same burn as from the physalia itself.


Giant octopuses, along with man-eating white sharks, have become a symbol of horror and fear in the underwater world. Many films and books convince us of the deadly threat posed by these mysterious animals. Their characteristic appearance made them the prototype of monsters, aliens and all kinds of evil spirits in numerous thrillers and action films.Indeed, the sight of an octopus or cuttlefish underwater is creepy and unusual, especially during a night dive. It seems that this creature is about to pounce on you, grab you with terrible tentacles with suction cups and carry you into the abyss, suck blood or do something else bad. And only experienced scuba divers know how harmless and peaceful cephalopods have – however, with rare exceptions such as the giant Doflein octopuses and Humboldt squids.

The main attribute of their formidable appearance – the tentacles – is nothing more than a modified leg, which in gastropods looks like a sole, and in bivalves – like a muscular process.The number of tentacles in cephalopods is different: for representatives of the decapod order, of course, there are ten of them, and for eight-legged, respectively, eight. In higher cephalopods, the inner surface of the tentacles flattened in cross-section contains suckers that allow mollusks to stick to the bottom surface, grab and hold prey. Nautilus have many small tentacles, which are pulled into the shell at the moment of danger. In addition to eight identical tentacles, squid and cuttlefish (the order of decapods) have two more hunting tentacles, much longer and wider at the ends.

Octopuses, as a rule, have eight identical tentacles, but in some species one tentacle differs sharply from the others – the so-called hectocotylized, thin and long: it plays the role of a male genital organ. During the mating season, the male puts it into the mantle cavity of the female and throws spermatophores into it – packages with spermatozoa fertilizing eggs. In Argonauts, the genital tentacle breaks off from the owner, finds the female itself and crawls into it. It can exist independently for quite a long time, snake-like swimming in search of its cephalopod lady.When it was first discovered in the mantle cavity of a female, it was decided that it was a worm-like parasite unknown to science. He was even given a name – hectocotyl.
Cephalopods move in a reactive manner. The part of the leg on the ventral side between the eyes forms a muscular funnel. At the first stage of the motor cycle, water fills the mantle cavity through the gap between the body and the mantle. Then the latter is pressed against the first, and the water is pushed with force through the opening of the funnel, and a powerful impulse sends the mollusk forward (more precisely, head back).Thanks to the efficiency of jet propulsion, squids develop fantastic speed in the water and are carried by rockets in the water column.

Photo by Andrey Shpatak

Despite their bizarre appearance, cephalopods remain true mollusks with shells of various shapes and degrees of reduction. Among the most beautiful inhabitants of the sea are nautilus with an external spiral-wound shell. It is divided into chambers filled with gas bubbles: by decreasing and increasing their volume, nautilus regulate their buoyancy.The mollusk itself is placed in the last, most spacious, chamber. The fossilized shells of their closest relatives, the extinct ammonites, encrusted with quartz and other rocks, are very beautiful and serve as a collectible. In the higher ones – decapods and eight-legged – cephalopods, the mantle grows over a shell, and that, immersed in a soft body, becomes internal. In cuttlefish, the spirally wound shell is still well developed and is even visible from the outside in the form of a raised protrusion. In squid, the shell is reduced to a simple horny plate.In the extinct belemnite squid, the shell looked like a funnel, which is reflected in the popular name of their fossilized remains: “devil’s fingers”. Argonauts have a kind of outer shell, which in origin has nothing to do with real shells of mollusks: it is secreted not by the mantle, but by the integuments and serves the females for bearing eggs. Octopuses have no shell at all.

The higher nervous activity of cephalopods is a classic subject of scientific research. It is no coincidence that the cephalopods are called primates of the sea: their brains in terms of complexity of organization surpass the brains of all other invertebrates, fish, amphibians, reptiles, birds and many mammals.Perhaps the cephalopods are the only aquatic creatures whose gaze gives the impression of being meaningful. This is due to the special structure of the eyes, which are more similar to humans than to the eyes of a marine invertebrate. They have everything that a higher vertebrate eye should have: the cornea, lens and pupil. True, accommodation is achieved not by changing the curvature of the lens, but by its approach to the retina and distance from it. Therefore, the focused gaze of the octopus, when it follows you underwater, resembles a human, which, combined with a frankly inhuman appearance, makes a strong impression and even instills fear.

Octopuses are great couch potatoes. They spend most of their time in caves, under rocks, in the holds of sunken ships and other cozy shelters. As a rule, octopuses choose a den with two entrances and exits: the front one, near which empty shells of eaten mollusks are usually piled up, and black, where they hide in case of danger. Usually, even large octopuses, when meeting a person, try to sneak away or hide, disguising themselves and changing their color to match the color of the bottom. But they can really become dangerous if disturbed in their native den or teased to the point of “white heat”.A large octopus can grasp and strongly squeeze an annoying diver with its tentacles, rip off the mask, rip a lung out of his mouth, damage vital equipment; with its mouthful beak, it is capable of breaking the mask and causing serious bodily harm.
In order not to run into trouble, you need to carefully monitor the color of the octopus, since its color scheme, as a rule, reflects the state and intentions of the animal. For example, the usual color of an octopus is variegated gray-purple; when he wants to hide and hide, he disguises himself under the surrounding bottom; in fear it turns white, and in fury it turns purple-red with iridescent streaks and spots.Therefore, if you see an octopus “reddened” with indignation, try to stay away from him and not bother him with curiosity.

There is information about the existence of huge octopuses up to 10 meters in range of tentacles, but there is no real evidence of these monsters attacking people yet. The real deadly threat to people is not hidden by giant octopuses, but by small octopuses. In the throat of the cephalopods, the ducts of the salivary glands open – in some species, their secret is poisonous. With their hard jaws, similar to the beak of a parrot, the mollusks make a wound in the skin, into which the poison cephalotoxin is injected.Immediately there is severe burning pain that gradually spreads throughout the body. Cephalotoxin contains anticoagulants that inhibit blood clotting, and therefore cephalopod wounds bleed for a long time. They turn red, swell and itch a lot, healing only after 10-12 days. Toxins from some octopus species cause numbness in the tongue and mouth, impaired vision, difficulty swallowing, suppression of tactile function and loss of coordination. The most aggressive species that bite divers include the California octopus Octopus fitchi and O.rubescens.

Particularly dangerous are the tiny octopuses of the genus Hapalochlaena, which reach a tentacle span of only 20 centimeters and are common in the Indian Ocean and off the coast of New Zealand, Papua New Guinea and Australia. When such an octopus is angry, blue and purple rings appear on its head and tentacles (hence its popular name “octopus with blue rings”). Some tourists, seeing these cute little animals for the first time, put them in their palm to admire the iridescent color change.The payback comes immediately: an imperceptible injection of a poisonous beak causes dry mouth, difficulty swallowing, nausea, bleeding from the wound, weakness, respiratory failure, loss of consciousness and death within two hours. Octopuses live in shallow water, so any child diving in a mask can spot them and be eager to catch them. Unfortunately, this is very easy to do, since the small mollusk is not able to escape as quickly as its larger counterparts. In the populated areas of the coast, octopuses build their homes in bottles, cans, tires and other garbage of human luxury.
A bitten octopus should immediately apply a tight bandage to the bite site and be prohibited from moving until qualified medical assistance arrives. In connection with impaired respiratory and cardiac activity, cardiopulmonary resuscitation may be necessary. Someone must constantly be near the victim to monitor his condition.