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Home › Sea Life › Marine Species › Invertebrates › Molluscs › Snails › Cones

Interesting Facts about Cone Shell Snails

[Cone Snail Phylum: Mollusca] [Class: Gastropoda] [Order: Neogastropoda] [Family: Conidae (cones)]

They are mostly associated with warm marine environments and around 800 species of cone shell snails belong to the family Conidae.

This section contains a compilation of fun and interesting facts about cone snails (cones), including where they are found, what they eat, and how they reproduce.

Where Do the Dangerous Cone Snails Live?

Despite having a wide ranging and global distribution, cone shells are more frequently seen in tropical and subtropical seas and oceans.

The richest diversity of the species flourish in the Indo-Pacific regions, especially Indonesia and the Philippines, but also:

• Atlantic Ocean (the coasts of Brazil, the Caribbean, and West Africa)
• Eastern Pacific (mainly along the coast of Central America and South America)
• Mediterranean Sea (e.g. the Mediterranean cone Conus ventricosus)

Cone snails are typical of most marine gastropods in that they occupy a broad scope of niches as habitats. Even so, most of them thrive around coral reef formations and even some artificial reefs, such as sunken shipwrecks and 3D printed coral reefs.

In general, the cone snail species prefer marine environments and subtidal habitats with soft sandy bottoms. So, it's quite common to see cone shells partly buried in oceanic silt and substrate.

Interesting Fact: Cone shell snails can tolerate a broad spectrum of depth ranges, from shallow tidal pools (only a few metres deep) to abyssal depths approaching one thousand metres (more than 3,000 feet below sea level), but they do not exist in freshwater environments.

Cone Snail Characteristics

The general shape and size of these predatory sea snails varies according to the species, of which there are over eight hundred validated examples.

It's fair to call the shell shape conical and tapered. It has a high spire and the aperture is narrow, and somewhat elongated.

But...

Compared with most of the small non-poisonous sea snails, the mantle cover of cones tends to be more colourful with bolder patterns.

Even though the sea snail body parts share some similarities throughout the classification, cone shell snails use an extended siphonal canal to detect their favourite prey - marine worms and small fishes.

Cone Snail Size

The pygmy cone (Conus pygmaeus) is one of the tiniest cone snails, and even fully grown adults rarely reach more than two (2) centimetres in overall length (less than one inch).

Whereas, the leopard cone (Conus leopardus) is one of the biggest in the entire species, measuring up to twenty three (23) centimetres long (9 inches).

Apart from being another large cone shell snail, the geography cone (Conus geographus) is also thought to be one of the deadliest snails in the world - and said to be responsible for more than 40 fatalities in humans.

Fun Fact: It also has the nickname of "cigarette cone snail" because the lethal speed of the toxin is enough to kill a victim before they could finish smoking a cigarette.

Cone Shell Sting

Like many of the sea snail species, cones are slow-moving and innocuous-looking creatures underwater. However, some cone shell snails possess a deadly venom that contains conotoxins (chemicals that cause muscle paralysis, heart failure, and death within minutes).

They use their proboscis (an arm-like chute) to fire the harpoon-tipped poisons into their victims. These poisonous conical shaped marine mollusks inject a lethal sting into their prey, and then calmly reel back the stunned creature to swallow it - whole!

Here's the thing:

Death is painless because conotoxins are a class of peptides that produce a painkilling drug.

Despite being deadly to their prey, cone snails rarely attack scuba divers.

Even so, official data on scuba diving deaths suggests the number of cone snail deaths per year is at least thirty (30), and possibly even higher due to issues with underreporting.

The force of envenomation from a large cone shell sting is alarmingly dangerous, because it is capable of piercing a diver's neoprene wetsuit. You could describe the typical jab of a cone fish harpoon as being similar to that of a bee sting.

Conotoxin Venom Delivery

Conotoxins block ion channels within a nervous system by interrupting the chemical signals. Cones produce more than one hundred different varieties of toxins that target specific muscle groups.

Some toxins affect the skeletal muscles, whereas others affect the major organs, particularly the heart. Seconds after the sting, communication stops between the muscle cells, and causes immediate paralysis. But, not every conotoxin has the same result.

Why?

Different strains cause different types of paralysis, most commonly excitotoxic shock and flaccid paralysis. Watch the cone shell sting video to see how excitotoxic shock causes all of the fish's muscles to contract simultaneously.

The dying fish (and its fins) become rigid. Conversely, flaccid paralysis makes the fish 'limp', because none of the muscles can contract.

Venomous toxins manufactured inside the venom duct deliver the lethal sting. These ducts can grow up to thirty centimetres, even though the snail may only be a few inches long.

The venom bulb (radula tooth) is similar to a small bellow, which contracts to pump the poison into sharp, teeth-like needles, called harpoons. These are stored inside the radula sac.

The prey dies, and it is then drawn into the expanding mouth (proboscis) - usually to be eaten whole. The deadly cocktail of poison contains a quantity of amino acids and produces one of the most venomous conotoxins known to scientists.

Pro Tip: After delivery of the toxin, the cone sea snail has up to twenty more harpoons in continuous development for use or for storage.

Anti-venom and Medical Uses

At the time of writing, there is no known anti-venom. Treatment includes providing basic life support for cone shell sting and any other appropriate emergency care procedures.

Scientists are using the venom in some pharmaceutical medicines and some drugs. They are particularly interested in the speed and accuracy that the venom has on the human anatomy and its receptors.

Some of the benefits include a lack of side effects when used as extremely powerful, non-addictive painkillers, and in heart rate reduction.

But wait - there's more:

Some drugs from cone shell snails are also used in medicine to treat chronic pain. They are one thousand (1,000) times more powerful than morphine.

A conotoxin-based drug, developed by a team in Melbourne University, Australia, is confident of producing a drug 10,000 times stronger than morphine (Ziconotide for example).

Medical researchers are confident that certain cone snail venoms may eventually replace morphine (e.g., narcotic analgesics) as mainstream pain relievers.

Pro Tip: A visual inspection is not the most accurate way to know which cone snails are deadly to humans. Hence, another section explains cone snail sting symptoms and treatment because all cone shell snails are venomous.

What Do Cone Snails Eat?

Not only are cone snails predatory carnivores, and more active at night, they also use a kind of ambush strategy to detect living prey.

So after spending much of the daylight hours hiding inside coral reefs or underneath rocks, they use chemosensory cues to strike different kinds of marine life with their venom-loaded harpoons.

In the wild, the extent of their diet and available sources of food is determined mostly by the species and their habitats. For example:

• Molluscivorous cone shell snails use a slower-acting venom to stun shelled victims. They mostly consume sea snails and other types of bivalve mollusks.
• Vermivorous cone snails feed primarily on segmented worms and other worm-like invertebrates.
• Piscivorous cone snails administer a fast-acting venom that instantly paralyses small fishes. Hence, these are the fish-eating cone species - and therefore they are also the most dangerous cone shell snails for humans.

Venomous Cone Snail Species

Cone Snail Reproduction

Conidae cone snails share many of the basic reproductive strategies used by marine gastropod snails, albeit with a few different features.

In fact, reproduction in cone shell snails occurs through "dioecism", a process where males and females have their own reproductive organs.

Fertilisation takes place when a male transfers his sperm directly to a female via a modified organ. So unlike many marine invertebrates, they do not release gametes into the water.

Then...

Following a successful fertilisation, the female cone snail lays egg capsules, many of which will be attached to solid structures, such as coral, rocks, or discarded fragments of animal shells. There may be up to a hundred cone snail eggs in each capsule.

The larvae of some species develop as veligers (free-swimming planktonic larvae) that drift aimlessly in the ocean for several weeks.

Whereas, veliconcha skip this part of the development phase and hatch as baby cone snails that swiftly crawl away to find a suitable place in the substrate to settle.

Threats and Predators

In the wild, the average lifespan of a cone snail is at least ten years, and it can be up to twenty (20) years in some species.

Despite the tough appearance from their thick outer shells, Conidae cones face a number of natural predators, and a few human-driven existential threats as well.

Some of the natural predators of cone shell snails include:

• Fish families (especially pufferfishes, triggerfishes, and wrasses)
• Crabs
• Marine mollusks (such as the carnivorous snails Drupella)

Some humans also collect cone snails for their shells. But, this is how some of them get envenomated while they handle them.

Other contributing factors for the decline in a few vulnerable areas include certain types of human behaviour (e.g. ocean acidification, coral reef destruction and degradation, overharvesting).

Important: The IUCN Red List of Threatened Species is a comprehensive source of information about the global conservation status of animals, fungi, and plants. Currently, the IUCN lists the vast majority of cone shell snails as being of "Least Concern" (LC). But, they list Conus felitae as "Vulnerable" (VU) and Conus cuneolus as "Critically Endangered" (CR).

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