Cone Snail

Venom from one cone snail is enough to theoretically kill 700 people.

Facts

• Cone snails have very beautiful shells, often decorated with different colors and patterns. They are collectors’ items and their being hard to come by makes them even  more valuable.
• Despite having aesthetically gorgeous shells, cone snails are very dangerous creatures. They are one of the most venomous animals in the world.
• The deadliest cone snail is the geography cone snail. This snail is four to six inches long and has a gorgeous shell which is sought after by shell collectors.
• Cone snails have killed almost 30 people officially. However, this is just the number of known deaths. The actual number is believed to be much higher.
• There are almost 1,000 species of cone snails, yet only two species have actually caused 27 recorded human fatalities: the geography snail and the textile snail.
• Picking up a cone snail or stepping on one would almost guarantee a sting from them. If you come across one while swimming in water, pedal faster in the opposite direction. A sting from a large cone spells almost certain death.
• The venom from one sting from a large cone snail can kill 15 people. The venom from one entire snail can kill an estimated 700 people.

Summary

The shells of the cone snail are so beautiful, alluring, and every shell collector’s dream. However, these snails are one of the deadliest types of animals in the world. They are venomous and their sting can either be as harmless as a bee sting or fatal enough to kill over a dozen people.

Scientific Name

Cone snails are named after their intricately designed conical shells. They are a sizeable group of venomous, carnivorous, predatory gastropods that are found in tropical and subtropical marine environments. The cone snail is the common name of the members of the family Conidae. Conidae contains 16 genera.

The exact number of cone snail species is uncertain, and most authors estimate there could be about 1,000 species. Until 2015, the known species of cone snails, around 600 at the time, were considered to be under one genus, Conus. Then, after some genetic experiments, modifications were made to the cone snail classification and three new genera were introduced: Conasprella, Californiconus, and Profundiconus. The hundreds of cone snail species were split into these four genera, with 85% of them being grouped under Conus.

Evolution and History

The cone snail is believed to have origins in the Indo-Pacific region. Cone snail fossils have been unearthed and date back to the Eocene Epoch which occurred about 56 million to 33.9 million years ago. Some of them also date back to the Holocene Epoch 12,000 to 11,500 years ago.

The cone snail underwent many periods of diversification, and have the highest rate of diversification of any marine gastropod. Research suggests that three main ancestral lines appeared soon after the origin of the species. These three lineages continue today, with one lineage having living species that can be found in the Indo-Pacific, another with species in the East Pacific and West Atlantic, and the last occurring only in the East Pacific.

Cone snails have varying diets, with most of them being vermivorous (worm feeders), and the rest molluscivorous (mollusk feeders), piscivorous (fish eaters), or more than one. Their diet is believed to have evolved at least a few times at varying degrees depending on their location and habitat.

Appearance

The reputation of the cone snail’s decorative beauty and terrifying speed of killing precedes it. Cone snail shells are coveted by shell collectors because of their otherworldly patterns and designs, as well as their perfectly geometric conical shape. Empty cone snail shells often find their way to sandy beaches where people pick them up as keepsakes.

Cone snails come in all sorts of colors like pink, white, blue, cream, brown, yellow, and some may be multicolored or come in just one solid color. All cone snail shells have whorls which are a full turn of the shell. They also have spires which are the whorls that are located on the wider end of the shell above the main shell whorl. The opening of the shell is long, just like the conch’s, and they have a small operculum. Cone snail shells can be smooth, rough, or even bumpy depending on the species.

These snails come in small, medium, and large sizes and measure from half an inch to nine inches long. They have a muscular foot which is used for movement as well as subduing prey. Cone snails also have a well-developed siphon which they use to sample their environment for prey while buried in the sand, as well as for respiration, and sucking in water for movement. The snail’s feet and siphon may also come in colorful patterns.

Cone snails have radular teeth whose appearance and number depends on the species. The teeth are usually serrated and is usually likened to a harpoon. They have two tentacles on their head and each of these contains an eye. The snails have gills between the mantle and their body.

All cone snails are venomous and the extent of the fatality of their venom depends on their sizes and species. Usually, the larger the size, the more fatal the venom. Venom from smaller cone snails are not usually dangerous to humans, but the larger snails can do some serious permanent damage. The cone snail “stings” its prey with a needle-like radula tooth which triggers the release of venom from their venom gland into the prey. This venom works by paralyzing the prey, allowing the snail to engulf it.

The venom from one cone snail is believed to be able to kill an estimated 700 people. Only two species of cone snails have caused human deaths from their bites: the geography snail (Conus geographus), and the textile snail (Conus textile).

Behavior

Cone snails usually hunt at night when they are the most active, but some are known to be active during dusk and dawn, making them crepuscular and nocturnal animals. These snails like to burrow in sand to wait for their prey to move pass or they lure them with the use of their proboscis. Cone snails are very slow creatures so they rely on the speed of their radula to catch nimble prey.

Even though cone snails are notorious for their ability to bring down bigger animals, and even human beings with just a sting, they are not aggressive in nature. Apart from their prey, they are known to only sting when they come in contact with humans, such as when they are stepped on, or picked up by divers. One sting contains enough venom to kill 15 people, and one snail can theoretically kill 700. It is safe to say, if you see a cone snail during your dive or in shallow water, swim in the opposite direction.

Only 27 recorded deaths have been known to have resulted from cone snail venom, but the real number is higher.

Cone snail sting symptoms include swelling, tingling in the stung area, numbness, localized pain, vomiting, muscle paralysis, blurred vision, respiratory paralysis, and, eventually, death. Depending on the severity of the sting, the effects can be felt immediately or after a few days. The deadliest cone snail, the geography snail, was jokingly given the nickname “cigarette snail” because a stung person would only have time to smoke one cigarette before dying.

Treatment for a severe cone snail sting involves pain relief by using hot water on the affected area, pressure immobilization to prevent the spread of the venom, bandaging, and CPR. However, there is currently no available anti-venom because of the complexity of the toxins.

Economic Importance

Because of the fast-acting and accurate nature of the toxins, cone snail venom is used in the pharmaceutical industry to treat illnesses. It is used to make pain relievers, including one that is 1,000 times stronger than morphine which was developed from the venom of the magician cone snail, Conus magus. Cone snail venom is being tested for potential use to cure other diseases such as Parkinson’s, Alzheimer’s, and epilepsy.

Diet

Cone snails are carnivorous animals that prey on other creatures. They eat marine worms, fish, mollusks, and other snails including cone snails. They can be arranged into three groups based on their dietary preferences:

• Vermivores: These cone snails primarily feed on worms.
• Piscivores: The cone snails in this group mainly prey on tropical fish. These types of cone snails happen to be the ones that are most dangerous to humans.
• Molluscivores: These cone snails prefer to eat mollusks and snails.

The feeding instruments of cone snails depend heavily on the snail’s diet. The radula is specially adapted to cater to each type of cone snail. The vermivores have short and wide radula with barbs close to the middle of it. Their radula is serrated. Piscivores possess a longer radula equipped with a long, smooth shaft and long, curved barbs at the tip of the shaft. The radula of the molluscivore cone snails are serrated over most of the shaft length and the barbs are heavy close to the base.

Cone snails usually hunt using two methods: the hook-and-line technique, and net-hunting.

In the hook-and-line method, the cone snail lures its prey over by brandishing its proboscis. Once the prey gets close enough, the snail stings it swiftly, paralyzing it before swallowing it whole. In the net-hunting method, the cone snail actually swallows the prey before stinging it with its radula. The cone snail is able to swallow its prey whole by expanding its proboscis.

Habitat and Population

Cone snails are tropical marine animals with a few exceptions. They can usually be found in warm, tropical zones such as the Great Barrier Reef, the Indian and Pacific Oceans, California, Southern Australia, Hawaii, and Baja California. Some cone snails are native to more semitropical zones like the Mediterranean, the Cape coast of South Africa, and southern California.

Cone snails typically inhabit shallow water close to coral reefs, under coral shelves, or mangroves. They can be found underneath rocks in the intertidal and subtidal zones. Cone snails like to bury themselves in sand with their siphon sticking out from the surface to probe for prey. They are unlikely to be found in very deep waters. Their average range of depth is from sea level to 656 feet below sea level.

Reproduction and Lifespan

Unlike many other types of snails, cone snails are believed to have distinct sexes. They are also monogamous and tend to live solitary lives until mating season comes around. The mating process usually last about 15 minutes and involves the male snail climbing on the female with his foot and fertilization takes place internally.

Two to three days after copulation, the female lays about 1,000 to 5,000 egg capsules on a solid surface. The average number of eggs the female cone snail lays is around 2,500. Each of the capsules contain a different number of eggs. About twenty days later, the eggs hatch veliger larvae where they can swim freely until they reach adulthood. Only a small number of cone snails actually make it to adulthood which is why so many eggs need to be laid.

Cone snails reach sexual maturity in 6 to 12 months. Not enough information is known about their life cycle, but they are estimated to live up to 10 to 20 years of age.

Predators and Threats

Cone snails have a very well-developed radula tooth which acts as both an attack system to catch prey, and a defense system to protect itself. Because of this, they do not have many predators in their adult stage of life. Their natural predators as adults include hermit crabs, sea turtles, rays, horseshoe crabs, and larger predatory fish. Human beings are also considered a predator due to their collection of cone shells. Cone snails can put up a good fight by stinging their assailants though.

In their hatchling stages as larvae, cone snails are predated on by nektonic fish and animals that feed via filler-feeding.

Related Reading:

• Giant African Land Snail
• 10 Incredible Snail Facts
• The 9 Largest Snails in The World

1. Wikipedia, Available here: https://en.wikipedia.org/wiki/Cone_snail
2. Wikipedia, Available here: https://en.wikipedia.org/wiki/Conidae
3. Wikipedia, Available here: https://en.wikipedia.org/wiki/Conus
4. Animal Diversity, Available here: https://animaldiversity.org/accounts/Conus_geographus/
5. Carnegie Museum of Natural History, Available here: https://carnegiemnh.org/cone-snails-another-thing-to-fear-in-case/
6. Aquarium of the Pacific, Available here: https://www.aquariumofpacific.org/onlinelearningcenter/species/cone_snails_general_description#:~:text=Most%20cone%20snails%20live%20in,or%20near%20piles%20of%20rubble.
7. Science Direct, Available here: https://www.sciencedirect.com/science/article/abs/pii/S1055790314001924