Cone snail

From Wikipedia, the free encyclopedia

iCone snails

Geography cone, Conus geographus

Scientific classification

Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Orthogastropoda
Superorder:	Caenogastropoda
Order:	Sorbeoconcha
Suborder:	Hypsogastropoda
Infraorder:	Neogastropoda
Superfamily:	Conoidea
Family:	Conidae Linnaeus, 1758

Genera

Asprella
Chelyconus
Conus
Floraconus
Leptoconus

The cone snails or cone shells (Conidae) are marine snails found in coral reefs.

Cone snails can grow up to 23 cm in length and are found in tropical waters. There are about 500 different species. They are carnivorous, generally eating marine worms, small fish, and even other molluscs. Because cone snails are slow-moving, they use a venomous harpoon (called a toxoglossan radula) to catch fast-moving prey such as fish. The venom of some species is powerful enough to kill a human being.

1 Harpoon and venom
2 Danger to humans
3 Medical use
4 Collection
5 External links

[edit] Harpoon and venom

The cone snail's harpoon is a modification of the radula, an organ in molluscs which acts as both tongue and 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 paralyses small fish almost instantly. The snail then retracts the radula, drawing the subdued prey into the mouth.

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 conotoxins. These are various peptides, targeting each a specific nerve channel or receptor. This venom also contains a pain-reducing component, first pacifying the victim, before immobilising and then killing it. Some cone snail venom contains tetrodotoxin, which is the same paralytic neurotoxin as that of the pufferfish, the blue-ringed octopus, and the Rough-skinned Newt.

[edit] Danger to humans

Textile cone, Conus textile

The bright colours and patterns of cone snails have led curious or acquisitive people to pick them up, sometimes with tragic consequences when the snail fires its harpoon in self-defense. About 30 human deaths have been recorded from cone snail envenomation. One species, Conus geographus, is known colloquially as the "cigarette snail," in the belief that the victim will have only enough time to smoke a cigarette before perishing. The harpoon can penetrate gloves or even wetsuits. 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 involved muscle paralysis, changes in 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.

[edit] Medical use

The venom of some cone snails, such as the magician cone snail, show 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 pharmaceuticals, such as AVC1, isolated from the Australian cone shell 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. 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.

[edit] Collection

Because of the intricate color patterns of cone shells, they have been called the most popular collectible shells.^[1] Conus gloriamaris^[2], the Glory of the Seas, was one of the most famous and sought-after seashells, with only a few specimens known, until sizable populations were discovered.^[3]

Eroded cone shells are also collected (and mimicked) to make puka shell jewelry.