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Do you love to collect shells? Shell collectors are highly captivated by the variety of colors and patterns (dotted, zigzag, and stripes) present in cone snails’ shells. The idea that a slow-moving snail could be dangerous rarely crosses our minds. But the beautiful cone snail is one of the deadliest marine animals in the world. For example, the species Conus geographus has more than 100 toxins in its venom.
Cone snails (genus Conus) are indigenous to reefs in the tropical waters of the Indian and Pacific Ocean zone. They inhabit tropical waters, but some species have adapted to temperate environments, such as southern California, the Cape Coast of South Africa, and the Mediterranean. They also live in the waters off Hawaii and Australia. There are more than 1,000 species of cone snails in the world.
Their size varies from half an inch up to nine inches long. Cone snails have well-developed siphons for detecting prey, water circulation, and respiration while buried in the sand. They conceal themselves under the sand to sneak up on and ambush their prey.
Cone snails use speed and venom to capture prey
A carnivorous predator, the cone snail hunts marine worms, fish, and gastropods for food. Amazingly, the cone snail’s proboscis fires a harpoon-like radula to penetrate its prey. The harpoon has a barb that is not easily dislodged from the prey. A biologist at Occidental College in Los Angeles who studied the cone snail found that it takes less than 200 microseconds for it to fire the harpoon and capture its prey.
The radula, a tooth-like adaptation of the snail, contains conotoxin which paralyzes the nervous and muscular system of its prey. The venom is stored in a venom gland and can flow through the hollow radula into a fish or worm.
The venom works nearly as fast as the harpoon and will halt the prey’s movement within seconds. The snail uses the harpoon to pull the prey next to it. The cunning cone snail can swallow its prey whole because the proboscis expands around the prey. Oddly enough, the harpoon-like radula is swallowed and a new one takes its place.
Dangers to humans
Two of the deadliest cone snails are Conus geographus and Conus textile. Even with less than 100 deaths recorded, a cone snail’s strike is still dangerous to humans. One of the first signs of a sting is pain followed by acute inflammation, redness, and swelling. The toxins injected will affect the nervous system, causing paralysis, cyanosis , and ultimately death. Death could occur in as little as five to eight hours.
Currently, there is no antitoxin to the venom.
If you find a cone snail that is still living in its shell, do not touch it, as all cone snails are venomous. If you are stung, immediately seek the help of medical professionals.
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Glossary
Indigenous: occurring naturally in a particular place
Siphon: a tube-like structure in which water (or, more rarely, air) flows, found in mollusks
Temperate: having a moderate climate which lacks extremes in temperature
Radula: a chitinous band in the mouth of most mollusks, set with numerous minute, horny teeth and drawn backward and forward over the floor of the mouth in the process of breaking up food
Proboscis: a venomous spaghetti-like appendage that wraps around and kills prey in marine animals
Barb: a sharp point that sticks out and backward from the point of an arrow, as in a fishhook
Conotoxin: a bioactive peptide that occurs in the venom of marine snails of the genus Conus.
Cyanosis: bluish discoloration of the skin resulting from poor circulation or inadequate oxygenation of the blood
Antitoxin: an antibody that can neutralize a specific toxin
References
Cone Snails¾ Another Thing to Fear. Carnegie Museum of Natural History. https://carnegiemnh.org/cone-snails-another-thing-to-fear-in-case/
De Long, William. Meet The Cone Snail, The One-Inch Sea Creature with Enough Deadly Toxin to Kill 700 People. May 7, 2022. https://allthatsinteresting.com/cone-snail
Bernwick, Leonie and Salvador, Andreia. June 8, 2017. Cornus Geographus¾ Harnessing the Power of this Mighty Mollusc. https://www.linnean.org/news/2017/06/08/8th-june-2017-world-oceans-day
Hiolski, Emma. Watch These Cunning Snails Stab and Swallow Fish Whole. May 29, 2019. https://www.kqed.org/science/1923898/watch-these-snails-stab-fish-and-swallow-them-whole
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