Cone snail
194041
225909231
2008-07-15T23:38:20Z
208.0.111.185
[[WP:UNDO|Undid]] revision 225889983 by [[Special:Contributions/160.133.1.228|160.133.1.228]] ([[User talk:160.133.1.228|talk]])
{{Refimprove|article|date=June 2008}}
{{Copyedit|article|date=June 2008}}
{{Taxobox
| name = Cone snails
| image = Conus-geographicus.jpg
| image_width = 250px
| image_caption = Geography cone, ''Conus geographus''
| regnum = [[Animal]]ia
| phylum = [[Mollusca]]
| classis = [[Gastropoda]]
| subclassis = [[Orthogastropoda]]
| superordo = [[Caenogastropoda]]
| ordo = [[Sorbeoconcha]]
| subordo = [[Hypsogastropoda]]
| infraordo = [[Neogastropoda]]
| superfamilia = [[Conoidea]]
| familia = '''Conidae'''
| familia_authority = [[Carolus Linnaeus|Linnaeus]], 1758
| subdivision_ranks = Genera
| subdivision =
''[[Asprella]]''<br />
''[[Chelyconus]]''<br />
''[[Conus]]''<br />
''[[Floraconus]]''<br />
''[[Leptoconus]]''
}}
The '''cone snails''' or '''cone shells''', sometimes simply known as "cones", (family '''Conidae'''), are a [[taxonomic]] family of medium-sized to large, sophisticated [[predatory]] sea [[snail]]s, [[marine (ocean)|marine]] [[gastropod]] [[mollusks]].
The shells of cone snails are shaped roughly like an [[ice-cream cone]]. The narrow end of the cone shell is the anterior end, and the wide end shows the usually very low [[spire (mollusc)|spire]] of the [[gastropod shell]].
These snails hunt and immobilize prey using a modified [[radula]]r tooth along with a poison gland containing [[neurotoxin]]s; this is launched out of its mouth in a [[harpoon]]-like motion.
Cone [[venom]] shows great promise as a source of new, medically important, substances.{{Fact|date=July 2008}}
Live cone shells should not be handled, as they are capable of "stinging" humans with unpleasant results. The sting of a few of the larger species of tropical cone snails can be fatal to a human being.
The shells of cone snails are often brightly colored and intricately patterned.
==Distribution==
This family is typically found in warm and tropical seas and oceans worldwide. However, some species are rather adapted to temperate environments, such as the Cape coast of South Africa, and indeed are endemic to these regions. There are about 500 different species.
==Habitat==
Many tropical cone snails live in or near [[coral reef]]s. Subtropical species may be found under rocks in the lower intertidal and shallow subtidal zones.
==Shell description==
The shells of cone snails are often brightly colored, and have interesting patterns, although in some species the color patterns may be partially or completely hidden under an opaque layer of [[periostracum]].
Some species of cone snails can grow up to 23 [[centimetre|cm]] in length and are found in tropical or subtropical waters.
==Life habits==
Cone snails are [[carnivore|carnivorous]], generally eating marine [[worm]]s, small [[fish]], [[mollusks]], and even other cone snails. Because cone snails are slow-moving, they use a [[venom (poison)|venomous]] [[harpoon]] (called a toxoglossan [[radula]]) to capture faster-moving prey such as fish. The venom of a few larger species is powerful enough to kill a [[human being]].
=== Harpoon and venoms ===
[[Image:Conus pennaeus attacks pair of Cymatium sp.jpg|thumb|300px|An individual ''[[Conus pennaeus]]'' preying upon one of a group of three snails of the species ''[[Cymatium nicobaricum]]'' in [[Hawaii]]]]
The cone snail's harpoon is a modification of the [[radula]], an organ in molluscs which acts as both [[tongue]] and [[tooth|teeth]]. The harpoon is hollow and barbed, and is attached to the tip of the radula inside the snail's throat. When the snail detects a prey animal nearby, it turns its mouth - a long flexible tube called a [[proboscis]] - towards the prey. The harpoon is loaded with venom and, still attached to the radula, is fired from the proboscis into the prey by a powerful muscular contraction. The venom paralyzes small fish almost instantly. The snail then retracts the radula, drawing the subdued prey into the mouth. After the prey is digested, the cone snail will regurgitate any indigestible material such as spines and scales, along with the disposable harpoon.
The venom of cone snails contains hundreds of different compounds, and its composition varies widely from one species of cone snail to another. The toxins in these various venoms are called [[conotoxin]]s. These are various [[peptide]]s, each targeting a specific nerve channel or receptor. Some cone snail venoms also contain a pain-reducing toxin, which the snail uses to pacify the victim before immobilising and then killing it. Some cone snail venoms contain a [[tetrodotoxin]], which is similar to the [[paralytic]] [[neurotoxin]]s found in [[pufferfish]], the [[blue-ringed octopus]], and the [[Rough-skinned Newt]].
==Relevance to humans==
=== Risk of being stung ===
[[Image:Textile cone.JPG|thumb|left|250px|A live Textile cone, ''[[Conus textile]]'', one of the three most dangerous cones to handle.]]
The bright colors and patterns of cone snails are attractive to the eye, and therefore people sometimes pick up the live animals and hold them in their hand for a while. This must not be done, because the snail may fire its harpoon in self-defense.
The "sting" of many of the smaller cone species may be no worse than that of a bee or hornet sting,{{Fact|date=June 2008}} but in the case of a few of the larger tropical species,{{clarifyme}} handling the snail can have fatal consequences. About 30 human deaths have been recorded from cone snail envenomation.{{Fact|date=June 2008}}
One species, the Geography cone, ''Conus geographus'', is also known colloquially as the "cigarette snail," a humorous exaggeration stating that, when stung by this creature, the victim will have only enough time to smoke a cigarette before dying.<ref>http://publications.nigms.nih.gov/findings/sept02/snails.html</ref><ref>http://animals.nationalgeographic.com/animals/invertebrates/geographers-cone-snail.html</ref> In the case of these larger species of cone snail, there may be risk of the harpoon penetrating [[glove]]s or [[wetsuit]]s.
Symptoms of a cone snail sting include intense [[pain]], swelling, numbness and tingling. Symptoms can start immediately or can be delayed in onset for days. Severe cases involve muscle [[paralysis]], changes in [[visual perception|vision]] and [[respiratory failure]] that can lead to [[death]]. There is no [[antivenom]], and treatment involves providing [[life support]] until the venom is metabolised by the victim.
=== Medical use of the venom ===
The venom of some cone snails, such as the Magician cone, ''Conus magus'', shows much promise for providing a non-addictive pain reliever 1000 times as powerful as, and possibly a replacement for, [[morphine]]. Many peptides produced by the cone snails show prospects for being potent [[pharmaceutical]]s, such as AVC1, isolated from the Australian species, the Queen Victoria cone, ''Conus victoriae''. This has proved very effective in treating post-surgical and neuropathic pain, even accelerating recovery from nerve injury. The first painkiller [[Ziconotide]] derived from cone snail toxins was approved by the U.S. [[Food and Drug Administration]] in December 2004 under the name "Prialt". Other drugs are in clinical and preclinical trials, such as compounds of the toxin that may be used in the treatment of Alzheimer's disease, Parkinson's disease, and [[epilepsy]].{{Fact|date=June 2008}}
=== Shell collecting ===
Due to the intricate color patterns of cone shells, they have been called the most popular [[conchology|collectible shells]].<ref>[http://www.worldwideconchology.com/Conidae.htm Conidae - worldwideconchology<!-- Bot generated title -->]</ref> <ref>[http://www.coneshell.net/pages/g_gloriamaris.htm Conus gloriamaris<!-- Bot generated title -->]</ref>
''Conus gloriamaris'', the Glory of the Seas cone, was in earlier centuries one of the most famous and sought-after seashells, with only a few specimens in private collections. This apparent rarity meant that shells of this species fetched very high prices, until finally the habitat for this cone was discovered, and sizable populations were located, bringing the price down dramatically. <ref>[http://www.oceanlight.com/lightbox.php?sp=Conus_gloriamaris Conus gloriamaris, Glory of the Seas Cone photos, Phillip Colla Natural History Photography :: Online Photo Search<!-- Bot generated title -->]</ref>
===As jewelry===
Naturally-occurring, beachworn, cone shell "tops" (the broken-off spire of the shell, which often has a hole worn at the tip) can function as beads without any further modification. In [[Hawaii]] these natural beads were traditionally collected from the beach drift in order to make [[puka shell]] jewelry.
Since it is hard to obtain enough naturally-occurring cone tops, almost all modern puka shell jewelry uses cheaper imitations, cut from thin shells of other species of mollusk, or even made of plastic.
== Footnotes ==
{{reflist}}
== External links ==
{{commonscat|Conidae}}
{{wikispecies|Conidae}}
* [http://grimwade.biochem.unimelb.edu.au/cone/index1.html Cone snail and conotoxins page]
* [http://biology.burke.washington.edu/conus/catalogue/index.php The ''Conus'' Biodiversity website]
* [http://www.worldwideconchology.com/Conidae.htm Conidae] from worldwide.conchology.com. Scroll down for many photographs.
* [http://www.theage.com.au/news/creative--media/painkiller-comes-out-of-its-shell/2005/07/24/1122143728598.html Pain-killer comes out of its shell] (The Age news article)
* [http://news.bbc.co.uk/1/hi/sci/tech/4846504.stm Venomous snails aid medical science] (BBC News Article).
* [http://www.coneshell.net ConeShell Collection Giancarlo Paganelli]
* [http://www.youtube.com/watch?v=B3qf8kawojk Cone Snail Video]
* [http://www.cnn.com/2008/LIVING/wayoflife/04/08/deadly.animals/index.html Deadly Critters That Might Save Your Life] (CNN)
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