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Conus geographus

Conus geographus, popularly called the geography cone or the geographer cone, is a species of predatory cone snail. It lives in reefs of the tropical Indo-Pacific, and hunts small fish. While all cone snails hunt and kill prey using venom, the venom of Conus geographus is potent enough to kill humans.[3]

Conus geographus
A live specimen of Conus geographus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Caenogastropoda
Order: Neogastropoda
Superfamily: Conoidea
Family: Conidae
Genus: Conus
Species:
C. geographus
Binomial name
Conus geographus
Synonyms[3]
  • Conus (Gastridium) geographus Linnaeus, 1758 · accepted, alternate representation
  • Gastridium geographus (Linnaeus, 1758 )

The variety Conus geographus var. rosea G. B. Sowerby I, 1833 is a synonym of Conus eldredi Morrison, 1955.

This species is the type species of :

  • Gastridium Modeer, 1793
  • Rollus Montfort, 1810
  • Utriculus Schumacher, 1817

Shell description

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C. geographus has a broad, thin shell, cylindrically inflated. Geography cones grow to about 10 to 15 cm (4 to 6 in) in length. The size of an adult shell varies between 43 and 166 mm (1.7 and 6.5 in). The ground color of the shell is pink or violaceous white, occasionally reddish. It has a mottled appearance, clouded and coarsely reticulated with chestnut or chocolate, usually forming two very irregular bands. This intricate brown-and-white pattern is highly prized by shell collectors.[4]

The geography cone has a wide, violaceous white or pink aperture and numerous shoulder ridges or spines.[3] The shell is covered with thread-like revolving striae, usually nearly obsolete except at the base. The flattened spire is striated and coronated.[3][5]

In comparison with other species, the shell has a noticeably wider and convex mid-body, with a flattened spire. Its walls are also noticeably thinner and lighter compared to other cone shells of similar length and size.

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    Apertural view
  •  
    Abapertural view
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    Apical view

Distribution

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Geography cones are common. They occur in the Red Sea, in the Indian Ocean off Chagos, Réunion, Madagascar, Mauritius, Mozambique and Tanzania. They are indigenous to the reefs of the Indo-Pacific region, except for Hawaii,[4] and off Australia (the Northern Territory, Queensland, Western Australia).

Ecology

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C. geographus is a piscivore that dwells in sediment of shallow reefs,[3] preying on small fish. Like the other cone snails, it fires a harpoon-like, venom-tipped modified tooth into its prey; the harpoon is attached to the body by a proboscis, and the prey is pulled inside for ingestion.

Venom

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Main article: Conotoxin

The geography cone snail is highly dangerous; live specimens should be handled with extreme caution.[3] C. geographus has the most toxic sting known among Conus species and there are reports for about three dozen human fatalities in 300 years. The venom has an LD50 toxicity in the range of 0.012-0.030 mg/kg.[4][6][7] The venom of the geography cone snail is a complex mix of hundreds of different toxins that is delivered through a toxoglossan radula, a harpoon-like tooth propelled from an extendable proboscis. There is no antivenom for a cone snail sting, and treatment consists of keeping victims alive until the toxins wear off.[4] The geography cone is also known colloquially as the "cigarette snail", a gallows humor exaggeration implying that, when stung by this creature, the victim will have only enough time to smoke a cigarette before dying.[8][9] In reality, even the most venomous cone snails take about one to five hours to kill a healthy human, though medical care must still be prompt as, without it, death is almost certain.[10]

Among the compounds found in cone snail venom are proteins which, when isolated, have great potential as pain-killing drugs. Research shows that certain component proteins of the venom target specific human pain receptors and can be up to 10,000 times more potent than morphine without morphine's addictive properties and side-effects.[4] Conotoxin-G is a toxin derived from the venom of C. geographus. Only 15-20 of the venom's 100-200 toxic peptides are used for feeding. It is believed that the other compounds are defensive, and that the venom is mainly used for defense.[6]

Insulin

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Recent research has revealed that C. geographus uses a form of insulin as a means of stunning its prey.[11] This insulin is distinct from its own (with shorter chains) and appears to be a stripped down version of those insulins found in fish. Once this venom passes through a fish's gills, the fish experiences hypoglycaemic shock, essentially stunning it and allowing for ingestion by the snail. This poison mixture has been referred to as nirvana cabal. Along with the tulip cone snail C. tulipa, no other species of any known lifeform is known to have used its own biological insulin as a weapon.[12]

References

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This article incorporates CC-BY-3.0 text from the reference.[3]

  1. ^ Kohn, A. (2013). "Conus geographus". IUCN Red List of Threatened Species. 2013: e.T192772A2158685. doi:10.2305/IUCN.UK.2013-1.RLTS.T192772A2158685.en. Retrieved 12 November 2021.
  2. ^ Linnaeus, C., 1758. Systema Naturae per Regna Tria Naturae, 10th ed., 1
  3. ^ a b c d e f g WoRMS (2010). Conus geographus Linnaeus, 1758. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=215499 on 2011-07-24
  4. ^ a b c d e "Geographic Cone Snail Profile". National Geographic Society. Archived from the original on July 5, 2007. Retrieved 31 December 2009.
  5. ^ George Washington Tryon, Manual of Conchology, vol. VI p. 88; 1879
  6. ^ a b Conus geographus Linnaeus 1758 penelope.uchicago.edu
  7. ^ Conus geographus Linnaeus, 1758 - Record: CONUS BIODIVERSITY WEBSITE CATALOGUE
  8. ^ "NIGMS - Findings, September 2002: Secrets of the Killer Snails". Archived from the original on 2017-11-07. Retrieved 2019-07-19.
  9. ^ Geographic Cone Snail, Geographic Cone Snail Profile, Facts, Information, Photos, Pictures, Sounds, Habitats, Reports, News - National Geographic
  10. ^ Kapil, Sasha; Hendriksen, Stephen; Cooper, Jeffrey S. (2020), "Cone Snail Toxicity", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 29262115, retrieved 2020-07-30
  11. ^ Ahorukomeye, P; Disotuar, M; Gajewiak, J; Karanth, S (February 2019). "Fish-hunting cone snail venoms are a rich source of minimized ligands of the vertebrate insulin receptor". eLife. 8 (8): e41574. doi:10.7554/eLife.41574. PMC 6372279. PMID 30747102.
  12. ^ Safavi-Hemami H, Gajewiak J, Karanth S, Robinson SD, et al. (February 2015). "Specialized insulin is used for chemical warfare by fish-hunting cone snails". Proc. Natl. Acad. Sci. U.S.A. 112 (6): 1743–8. Bibcode:2015PNAS..112.1743S. doi:10.1073/pnas.1423857112. PMC 4330763. PMID 25605914.

Further reading

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  • Linnaeus, C. (1758). Systema Naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Editio decima, reformata. Laurentius Salvius: Holmiae. ii, 824 pp Archived 2017-06-13 at the Wayback Machine
  • Dufo, M.H. 1840. Observations sur les Mollusques marins, terrestres et fluviatiles des iles Séchelles et des Amirantes. Annales des Sciences Naturelles, Paris 2 14, Zoologie: 45-80 (extrait), 166-221(suite)
  • Reeve, L.A. 1843. Monograph of the genus Conus. pls 1-39 in Reeve, L.A. (ed.). Conchologica Iconica. London : L. Reeve & Co. Vol. 1.
  • Hedley, C. 1899. The Mollusca of Funafuti. Part 1. Gastropoda. Memoirs of the Australian Museum 3(7): 395-488, 49 text figs
  • Schepman, M.M. 1913. Toxoglossa. 384-396 in Weber, M. & de Beaufort, L.F. (eds). The Prosobranchia, Pulmonata and Opisthobranchia Tectibranchiata, Tribe Bullomorpha, of the Siboga Expedition. Monograph 49. Siboga Expeditie 32(2)
  • Allan, J.K. 1950. Australian Shells: with related animals living in the sea, in freshwater and on the land. Melbourne : Georgian House xix, 470 pp., 45 pls, 112 text figs.
  • Satyamurti, S.T. 1952. Mollusca of Krusadai Is. I. Amphineura and Gastropoda. Bulletin of the Madras Government Museum, Natural History ns 1(no. 2, pt 6): 267 pp., 34 pls
  • Gillett, K. & McNeill, F. 1959. The Great Barrier Reef and Adjacent Isles: a comprehensive survey for visitor, naturalist and photographer. Sydney : Coral Press 209 pp.
  • McMichael, D.F. 1960. Shells of the Australian Sea-Shore. Brisbane : Jacaranda Press 127 pp., 287 figs.
  • Rippingale, O.H. & McMichael, D.F. 1961. Queensland and Great Barrier Reef Shells. Brisbane : Jacaranda Press 210 pp.
  • Wilson, B.R. & Gillett, K. 1971. Australian Shells: illustrating and describing 600 species of marine gastropods found in Australian waters. Sydney : Reed Books 168 pp.
  • Hinton, A. 1972. Shells of New Guinea and the Central Indo-Pacific. Milton : Jacaranda Press xviii 94 pp.
  • Salvat, B. & Rives, C. 1975. Coquillages de Polynésie. Tahiti : Papéete Les editions du pacifique, pp. 1–391.
  • Cernohorsky, W.O. 1978. Tropical Pacific Marine Shells. Sydney : Pacific Publications 352 pp., 68 pls.
  • Wilson, B. 1994. Australian Marine Shells. Prosobranch Gastropods. Kallaroo, WA : Odyssey Publishing Vol. 2 370 pp.
  • Röckel, D., Korn, W. & Kohn, A.J. 1995. Manual of the Living Conidae. Volume 1: Indo-Pacific Region. Wiesbaden : Hemmen 517 pp.
  • Filmer R.M. (2001). A Catalogue of Nomenclature and Taxonomy in the Living Conidae 1758 - 1998. Backhuys Publishers, Leiden. 388pp
  • Tucker J.K. (2009). Recent cone species database. September 4, 2009 Edition
  • Tucker J.K. & Tenorio M.J. (2009) Systematic classification of Recent and fossil conoidean gastropods. Hackenheim: Conchbooks. 296 pp
  • Puillandre N., Duda T.F., Meyer C., Olivera B.M. & Bouchet P. (2015). One, four or 100 genera? A new classification of the cone snails. Journal of Molluscan Studies. 81: 1-23
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    Conus geographus Linnaeus, C., 1758
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    Conus geographus Linnaeus, C., 1758
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    Conus geographus Linnaeus, C., 1758
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    Conus geographus Linnaeus, C., 1758
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