Are there poisonous snails? - Types and photos

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Animals with little mobility have had to develop interesting adaptations to defend themselves against predators and to obtain food. Within the water are sea snails, whose families have developed powerful toxins that position them as one of the most poisonous animals in the animal kingdom. Even its toxins have medical qualities of great value to humans. Keep reading this Green Ecologist article where you will learn which are the main poisonous snails, what if you happen to meet one and where they live.

What are poisonous snails

We can classify poisonous snails into three different families: the Conidae, the Turridae and the Terebridae. Next, we are going to see them in more detail:


Conids are sea snails, which inhabit the intertidal zone of tropical areas, especially associated with shallow and warm water coral systems. It is rare to find them in temperate areas, but when they do, they are found in deep areas.

The main characteristics of the Conidae are the following:

  • Have eye-catching geometric patterns: which are drawn on its conical outer shell.
  • Are nocturnal predators: since they feed on small fish, mollusks and worms.
  • It has a complex feeding system: despite being a snail with little movement.
  • They have a hollow harpoon: where the food is stored in a sack until it is going to be used, unlike mollusks they normally have a radula in the mouth that is like sandpaper that scrapes the food.
  • It detects its prey with its osphradium: it is an olfactory organ of mollusks and, once it has located the prey, it launches its harpoon. During the outward journey, the harpoon fills with the neurotoxin called conotoxin, which is stored in another sac. The prey crawls to the mouth with the poison-impregnated harpoon and is digested.

This conotoxin has hundreds of variants depending on the species, but they all work blocking nerve conduction and immobilizing the muscles. Some only immobilize without killing, while others do.

Next, we are going to see some examples of poisonous snails of the Conidae family:

  • Conus textile: measures 9 to 15 centimeters and lives in the Indo-Pacific Ocean. This species is dangerous for humans, due to its powerful poison with ability to kill to large prey.
  • Conus purpurascens: is one of the conids that more bites cause in man. It measures 3 to 8 centimeters and its shell is light purple with brown or black bands or spots. It is associated with rocks in the intertidal zone.
  • Conus geographus: This snail is known as the "cigar snail" in a colloquial way because the time for its poison to annihilate is the duration it takes to finish a cigarette. This is one of the species more lethal for the human.

The Conidae are part of the mollusk family. Therefore, if you want to know more about Mollusks: characteristics, types and examples, here is an article where we explain it to you.


The Turridae family contains predatory sea snailsBut where do poisonous snails live? In the case of these snails, they inhabit the coastal surface area of a maximum depth of 200 meters, but most live in deep waters of 50 to 500 meters throughout the planet. Some of the characteristics of the Turridae are the following:

  • Are the largest group of marine gastropods: with more than 4 thousand species.
  • They have one poisonous gland in the radula of three or two teeth: some have lost the latter to be completely replaced by the gland. A muscular poison bulb is attached to it. This gland is used to capture food or to escape predators.
  • They have one variety of shapes: regarding their shells.
  • They have a serrated called sinus: it is located in the last fold of its shell, where it is accommodated in the exhaling channel.
  • They feed mainly on polychaete worms.
  • They are usually from small size: they measure an average of 5 mm and have not been studied much because they are small, nocturnal, burial and deep-sea.

One of the examples of poisonous snails of the Turridae family is the Gemmula periscelida, which lives in the Atlantic Ocean and is 2 to 5 centimeters in size. It is light brown in color, and its shell has complex and highly aesthetic ornamentation. It feeds on wandering or sedentary annelids, sipuncúlids and nemerteans.

If you want to know more about, here is another post about the Atlantic Ocean: characteristics, flora and fauna.


The Terebridae family are marine snails that live in warm tropical waters. They are known as drill snails due to its numerous curls, which are also characteristic for being flattened instead of convex as is common. In the anterior canal they have an opening and their columella has two folds. They use venom similar to conotoxin to capture their prey annelids.

Here you can find out more information about What are annelids: classification and examples.

An example of a poisonous Terebridae is the Terebra subulata, which measures between 7 and 20 centimeters. It is very long and thin, with black spots on brown. It feeds on polychaete worms that it finds digging in the most superficial layers of the sandy marine substrate, captured with the help of its venom. This is just effective against annelids and harmless in vertebrates.

What happens if you touch a poisonous snail

Touching a poisonous snail does not hurt, what does hurt is the reaction that the body will have when it perceives you as a threat. Any approach that is strange to you will be answered with a sting. Most poisonous snails are not lethal, only wasp-like pain is felt. In case of taking them by hand, the widest part of the shell is the least likely to be reached by the harpoon, but it should be avoided anyway.

The harpoon blow is the conid's first approach and feels like a needle sting. We can differentiate the symptoms into:

  • Initial symptoms: they begin when the poison is released. It generates a burning sensation, decreased blood flow and inflammation at the wound site and little by little they spread throughout the body. The sensation is usually perceived especially on the lips.
  • Late symptoms: they are expressed as the absence of a knee jerk reflex, which occurs in the knee, loss of voice, itchy skin, blurred vision and a feeling of suffocation.
  • Severe symptoms very advanced: present in paralysis of voluntary muscles and lack of coordination. Complicated cases can lead to coma or death.

Still, if seen on time, recovery time can be from hours to weeks.

Although not all snails are poisonous and not all poisons are lethal to humans, it is better to apply the precautionary principle: If you do not know the effect that something will have, it is better not to approach or touch it. Involuntary approaches can occur when you visit the beach, so it is always advisable to wear water shoes to avoid accidents.

Use of poisonous snails in medicine

The use of venom from poisonous snails in medicine contemplates different options, including:

  • Conotoxin has been extensively studied in the field of medicine and it is easy to replicate it in the laboratory. It has been incorporated into neurophysiology for treatments of nervous system diseases, such as Parkinson's or Alzheimer's.
  • It has been used for potent drugs of analgesic character FDA approved with the ability to reduce pain 100 times more than morphine and without generating dependency.
  • The venom of marine snails is also being studied for the muscular atrophy caused by age, called sarcopenia. The venom is used to enhance the responsiveness of acetylcholine receptors.

If you want to read more articles similar to Are there poisonous snails?, we recommend that you enter our category of Animal Curiosities.

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  • The Sun of Tulancingo. (2022). Sea snail venom could fight Alzheimer's and Parkinson's. Available at:
  • Field, J., Calderón, R. (2010). Conus snail bite. Clinical Bulletin Hospital Infantil Estado de Sonora 2010; 27 (2): 137-141.
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