The 2014 classification of the superfamily Conoidea groups only cone snails in the family Conidae. Some previous classifications grouped the cone snails in a subfamily, Coninae.
As of March 2015 Conidae contained over 800 recognized species, varying widely in size from lengths of 1.3 cm to 21.6 cm. Working in 18th-century Europe,Carl Linnaeus knew of only 30 species that are still considered valid.
The snails within this family are sophisticatedpredatory animals.[2] They hunt and immobilize prey using a modifiedradular tooth along with a venom gland containingneurotoxins; the tooth is launched out of the snail's mouth in aharpoon-like action.
Because all cone snails are venomous and capable ofstinging humans, live ones should be handled with great care or preferably not at all.
In theJournal of Molluscan Studies, in 2014, Puillandre, Duda, Meyer, Olivera & Bouchet presented a new classification for the old genusConus. Using 329 species, the authors carried out molecular phylogenetic analyses. The results suggested that the authors should place all living cone snails in a single family, Conidae, containing the following genera:
The authors grouped 85% of all known cone snail species underConus. They recognized 57 subgenera withinConus, and 11 subgenera within the genusConasprella.[3]
Prior to 1993, the family Conidae contained onlyConus species. In 1993 significant taxonomic changes were proposed by Taylor, et al.,:[4] the family Conidae was redefined as several subfamilies. The subfamilies included many subfamilies that had previously been classified in the familyTurridae, and theConus species were moved to the subfamilyConinae.
In further taxonomic changes that took place in 2009 and 2011, based uponmolecular phylogeny (see below), the subfamilies that were previously in the familyTurridae were elevated to the status of families in their own right. This left the family Conidae once again containing only those species that were traditionally placed in that family: the cone snail species.
In 2009 John K. Tucker and Manuel J. Tenorio proposed a classification system for the cone shells and their allies (which resorb their inner walls during growth) was based upon acladistical analysis of anatomical characters including theradular tooth, themorphology (i.e., shell characters), as well as an analysis of priormolecular phylogeny studies, all of which were used to construct phylogenetic trees.[6] In their phylogeny, Tucker and Tenorio noted the close relationship of the cone species within the various clades, corresponding to their proposed families and genera; this also corresponded to the results of prior molecular studies by Puillandreet al. and others.[7][8][9][10][11][12][13] This 2009 proposed classification system also outlined the taxonomy for the other clades ofConoidean gastropods (that donot resorb their inner walls), also based upon morphological, anatomical, and molecular studies, and removes theturrid snails (which are a distinct large and diverse group) from the cone snails, and creates a number of new families.[6] Tucker and Tenorio’s proposed classification system for the cone shells and their allies (and the other clades ofConoidean gastropods ) is shown inTucker & Tenorio cone snail taxonomy 2009.
The classification by Bouchet et al. (2011)[14] was based on mitochondrial DNA and nuclear DNA testing, and built on the prior work by J.K. Tucker & M.J. Tenorio (2009), but did not include fossil taxa.[6][14]
This is a list of what were recognized extant genera within Conidae as per J.K. Tucker & M.J. Tenorio (2009), and Bouchet et al. (2011):[6][14] However, all these genera have become synonyms of subgenera within the genusConus as per the revision of the taxonomy of the Conidae in 2015[3]
Following Taylor et al., from 1993 to 2011, the family Conidae was defined as including not only the cone snails, but also a large number of other genera which are commonly known as"turrids". However, as a result ofmolecular phylogeny studies in 2011, many of those genera were moved back to theTurridae, or were placed in new "turrid" families within the superfamilyConoidea. The following list of genera that used to be included in Conidae is retained as a historical reference:
Species in the family Conidae are found in the tropical and subtropical seas of the world, in fourbiogeographic regions, including: theIndo-Pacific (with 60% of all species), theTropical Eastern Pacific, the westernTropical Atlantic, and the eastern Tropical Atlantic, plus 10 species in the warm temperateAgulhas bioregion on the southern coast of South Africa. Fewer than one percent of fossil species have been found in more than one of the above regions.[23]
The oldest known fossil of Conidae is from the lowerEocene, about 55 million years ago. Analysis ofnucleotide sequences indicate that all living species of Conidae belong to one of twoclades that diverged about 33 million years ago. One clade includes most of the species in the eastern Pacific and western Atlantic regions, which were connected by theCentral American Seaway until the emergence of theIsthmus of Panama less than three million years ago. The other clade includes most of the species in the eastern Atlantic and Indo-Pacific regions, which were connected by theNeo-Tethys Sea until 21 to 24 million years ago.[23]
Most cone snails appear to reproduce sexually, with separate sexes and internal fertilization. varying numbers of eggs in egg capsules laid in substrate by cone snails. Hatchlings are of two types, the veligers (larvae that swim freely) and veliconcha (baby snail).[24]
There are approximately 30 records of humans killed by cone snails. Human victims suffer little pain, because the venom contains an analgesic component. Some species reportedly can kill a human in under five minutes, thus the name "cigarette snail" as supposedly one only has time to smoke a cigarette before dying. Cone snails can sting through a wetsuit with their harpoon-like radular tooth, which resembles a transparent needle.[25]
Normally, cone snails (and many species in the superfamilyConoidea) use their venom to immobilize prey before engulfing it. The venom consists of a mixture ofpeptides, calledconopeptides. The venom is typically made up of 10 to 30amino acids, but in some species as many as 60. The venom of each cone snail species may contain as many as 200 pharmacologically active components. It is estimated that more than 50,000 conopeptides can be found, because every species of cone snail is thought to produce its own specific venom.
Cone-snail venom has come to interest biotechnologists and pharmacists because of its potential medicinal properties. Production of synthetic conopeptides has started, usingsolid-phase peptide synthesis.
A component of the venom ofConus magus, ω-conotoxin, is now marketed as theanalgesicziconotide, which is used as a last resort in chronic and severe pain. Conopeptides are also being looked at as anti-epileptic agents and to help stop nerve-cell death after a stroke or head injury. Conopeptides also have potential in helping against spasms due tospinal cord injuries, and may be helpful in diagnosing and treating small cellcarcinomas in the lung.
Thebiotechnology surrounding cone snails and their venom has promise for medical breakthroughs; with more than 50,000conopeptides to study, the possibilities are numerous.[26]
^Fleming J. (June 1822).The philosophy of zoology, a general view of the structure, functions and classification of animals2. Constable & Co., Edinburgh, 618 pp., Conidae is on the page 490.
^Piper R. (2007).Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals,Greenwood Press.
^abTaylor J. D., Kantor Y. I. & Sysoev A. V. (1993). "Foregut anatomy, feeding mechanisms, relationships and classification of Conoidea (Toxoglossa) (Gastropoda)." Bull. Br. Mus. (Nat. Hist.) Zool. 59: 125–169.
^abcdTucker J.K. & Tenorio M.J. (2009) Systematic classification of Recent and fossil conoidean gastropods. Hackenheim: Conchbooks. 296 pp., at p. 133
^abP.K. Bandyopadhyay, B.J. Stevenson, J.P. Ownby, M.T. Cady, M. Watkins, & B. Olivera (2008),The mitochondrial genome of Conus textile, coxI-conII intergenic sequences and conoidean evolution. Molecular Phylogenetics and Evolution 46: 215-223.
^abS.T. Williams & T.F. Duda, Jr. (2008),Did tectonic activity stimulate Oligo-Miocene speciation in the Indo-West Pacific? Evolution 62:1618-1634.
^abR.L. Cunha, R. Castilho, L. Ruber, & R. Zardoya (2005),Patterns of cladogenesis in the venomous marine gastropod genus Conus from the Cape Verde Islands Systematic Biology 54(4):634-650.
^abT.F. Duda, Jr. & A.J. Kohn (2005),Species-level phylogeography and evolutionary history of the hyperdiverse marine gastropod genus Conus, Molecular Phylogenetics and Evolution 34:257-272.
^abT.F. Duda, Jr. & E. Rolan (2005),Explosive radiation of Cape Verde Conus, a marine species flock, Molecular Ecology 14:267-272.
^abB. Vallejo, Jr. (2005),Inferring the mode of speciation in the Indo-West Pacific Conus (Gastropoda: Conidae), Journal of Biogeography 32:1429-1439.
^abN. Puillandre, S. Samadi, M. Boesselier, A. Sysoev, Y. Kantor, C. Cruaud, A. Couloux, & P. Bouchett (2008),Starting to unravel the toxoglossan knot: molecular phylogeny of the "turrid" (Neogastropoda: Conoidea), Molecular Phylogenetics and Evolution 47:1122-1134.
^Tucker, J. K. & Stahlschmidt, P. (2010)A second species of Pseudoconorbis (Gastropoda: Conoidea) from India. Miscellanea Malacologica 4(3):31-34.
^Watkins, M., Corneli, P.S., Hillyard, D., & Olivera, B.M. (2010)Molecular phylogeny of Conus chiangi (Azuma, 1972) (Gastropods:Conidae). The Nautilus 124(3):129-136.
^Tucker, J. K., Tenorio, M. J. & Stahlschmidt, P. (2011)The genus Benthofascis (Gastropoda: Conoidea): a revision with descriptions of new species. Zootaxa 2796:1-14.
^Tucker, J. K. & Tenorio, M. J. (2011)New species of Gradiconus and Kohniconus from the western Atlantic (Gastropoda: Conoidea: Conidae, Conilithidae).Miscellanea Malacologica 5(1):1-16.
^Petuch, E. J. & Sargent, D. M. (2011)New species of Conidae and Conilithidae (Gastropoda) from the tropical Americas and Philippines. With notes on some poorly-known Floridian species. Visaya 3(3):116-137.
^Petuch & Drolshage (2011)Compendium of Florida Fossil Shells, Volume 1 MDM Publications, Wellington, Florida, 432 pp.
^C.M.L. Afonso & M.J. Tenorio (August 2011),A new, distinct endemic Africonus species (Gastropoda, Conidae) from Sao Vicente Island, Cape Verde Archipelago, West Africa, Gloria Maris 50(5): 124-135
Taylor, J. D.; Kantor, Yu. I.; Sysoev, A. V. (1993). "Foregut anatomy, feeding mechanisms, relationships and classification of Conoidea (Toxoglossa) (Gastropoda)".Bull. Nat. Hist. Mus.59:125–169.
Tucker J.K. & Tenorio M.J. (2009),Systematic Classification of Recent and Fossil Conoidean Gastropods, ConchBooks, Hankenheim, Germany, 295 pp.
Berschauer D. (2010).Technology and the Fall of the Mono-Generic FamilyThe Cone Collector15: pp. 51–54
