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 sophisticated predatory animals.[2] They hunt and immobilize prey using a modified radular tooth along with a venom gland containing neurotoxins; the tooth is launched out of the snail's mouth in a harpoon-like action.
Because all cone snails are venomous and capable of "stinging" humans, live ones should be handled with great care or preferably not at all.
Current taxonomy
In the Journal of Molluscan Studies, in 2014, Puillandre, Duda, Meyer, Olivera & Bouchet presented a new classification for the old genus Conus. 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 under Conus. They recognized 57 subgenera within Conus, and 11 subgenera within the genus Conasprella.[3]
History of the taxonomy
Overview
Prior to 1993, the family Conidae contained only Conus 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 family Turridae, and the Conus species were moved to the subfamily Coninae.
In further taxonomic changes that took place in 2009 and 2011, based upon molecular phylogeny (see below), the subfamilies that were previously in the family Turridae 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 a cladistical analysis of anatomical characters including the radular tooth, the morphology (i.e., shell characters), as well as an analysis of prior molecular 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 Puillandre et al. and others.[7][8][9][10][11][12][13] This 2009 proposed classification system also outlined the taxonomy for the other clades of Conoidean gastropods (that do not resorb their inner walls), also based upon morphological, anatomical, and molecular studies, and removes the turrid 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 of Conoidean gastropods ) is shown in Tucker & Tenorio cone snail taxonomy 2009.
2011, Bouchet et al.
In 2011 Bouchet et al. proposed a new classification in which several subfamilies were raised to the rank of family:[14]
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]
2009, 2011, list of genera from Tucker & Tenorio, and Bouchet et al.
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 genus Conus as per the revision of the taxonomy of the Conidae in 2015 [3]
Afonsoconus Tucker & Tenorio, 2013: synonym of Conus (Afonsoconus) Tucker & Tenorio, 2013 represented as Conus Linnaeus, 1758
Africonus Petuch, 1975: synonym of Conus (Lautoconus) Monterosato, 1923 represented as Conus Linnaeus, 1758
Arubaconus Petuch, 2013: synonym of Conus (Ductoconus) da Motta, 1991 represented as Conus Linnaeus, 1758
Asprella Schaufuss, 1869: synonym of Conus (Asprella) Schaufuss, 1869 represented as Conus Linnaeus, 1758
Atlanticonus Petuch & Sargent, 2012: synonym of Conus (Atlanticonus) Petuch & Sargent, 2012 represented as Conus Linnaeus, 1758
Attenuiconus Petuch, 2013: synonym of Conus (Attenuiconus) Petuch, 2013 represented as Conus Linnaeus, 1758
Austroconus Tucker & Tenorio, 2009 synonym of Conus (Austroconus) Tucker & Tenorio, 2009 represented as Conus Linnaeus, 1758
Bathyconus Tucker & Tenorio, 2009: synonym of Conasprella (Fusiconus) Thiele, 1929, represented as Conasprella Thiele, 1929
Bermudaconus Petuch, 2013: synonym of Conus (Bermudaconus) Petuch, 2013 represented as Conus Linnaeus, 1758
Boucheticonus Tucker & Tenorio, 2013: synonym of Conasprella (Boucheticonus) Tucker & Tenorio, 2013 represented as Conasprella Thiele, 1929
Brasiliconus Petuch, 2013: synonym of Conus (Brasiliconus) Petuch, 2013 represented as Conus Linnaeus, 1758
Calamiconus Tucker & Tenorio, 2009: synonym of Conus (Lividoconus) Wils, 1970 represented as Conus Linnaeus, 1758
Calibanus da Motta, 1991: synonym of Conus (Calibanus) da Motta, 1991 represented as Conus Linnaeus, 1758
Cariboconus Petuch, 2003: synonym of Conus (Dauciconus) Cotton, 1945 represented as Conus Linnaeus, 1758
Thalassiconus Tucker & Tenorio, 2013: synonym of Calibanus da Motta, 1991, synonym of Conus (Calibanus) da Motta, 1991 represented as Conus Linnaeus, 1758
Theliconus Swainson, 1840: synonym of Hermes Montfort, 1810, synonym of Conus (Hermes) Montfort, 1810 represented as Conus Linnaeus, 1758
Thoraconus da Motta, 1991: synonym of Fulgiconus da Motta, 1991, synonym of Conus (Phasmoconus) Mörch, 1852 represented as Conus Linnaeus, 1758
Trovaoconus Tucker & Tenorio, 2009, synonym of Conus (Kalloconus) da Motta, 1991 represented as Conus Linnaeus, 1758
Tuckericonus Petuch, 2013: synonym of Conus (Dauciconus) Cotton, 1945 represented as Conus Linnaeus, 1758
Tuliparia Swainson, 1840: synonym of Gastridium Modeer, 1793, synonym of Conus (Gastridium) Modeer, 1793 represented as Conus Linnaeus, 1758
Turriconus Shikama & Habe, 1968, synonym of Conus (Turriconus) Shikama & Habe, 1968 represented as Conus Linnaeus, 1758
Utriculus Schumacher, 1817: synonym of Gastridium Modeer, 1793, synonym of Conus (Gastridium) Modeer, 1793 represented as Conus Linnaeus, 1758
Varioconus da Motta, 1991: synonym of Conus (Lautoconus) Monterosato, 1923 represented as Conus Linnaeus, 1758
Viminiconus Tucker & Tenorio, 2009: synonym of Conasprella (Fusiconus) da Motta, 1991 represented as Conasprella Thiele, 1929
Virgiconus Cotton, 1945: synonym of Conus (Virgiconus) Cotton, 1945 represented as Conus Linnaeus, 1758
Virroconus Iredale, 1930: synonym of Conus (Virroconus) Iredale, 1930 represented as Conus Linnaeus, 1758
Vituliconus da Motta, 1991: synonym of Conus (Strategoconus) da Motta, 1991 represented as Conus Linnaeus, 1758
Ximeniconus Emerson & Old, 1962: synonym of Conasprella (Ximeniconus) Emerson & Old, 1962 represented as Conasprella Thiele, 1929
Yeddoconus Tucker & Tenorio, 2009: synonym of Conasprella (Endemoconus) Iredale, 1931 represented as Conasprella Thiele, 1929
1993 to 2011 list of genera
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 of molecular phylogeny studies in 2011, many of those genera were moved back to the Turridae, or were placed in new "turrid" families within the superfamily Conoidea. 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 four biogeographic regions, including: the Indo-Pacific (with 60% of all species), the Tropical Eastern Pacific, the Western Tropical Atlantic, and the Eastern Tropical Atlantic, plus 10 species in the warm temperate Agulhas 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]
Paleontology
The oldest known fossil of Conidae is from the lower Eocene, about 55 million years ago. Analysis of nucleotide sequences indicate that all living species of Conidae belong to one of two clades 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 the Central American Seaway until the emergence of the Isthmus 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 the Neo-Tethys Sea until 21 to 24 million years ago.[23]
Cone snail reproduction
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]
Cone snail venom characteristics and biotech
Cone snail venom apparatus
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 superfamily Conoidea) use their venom to immobilize prey before engulfing it. The venom consists of a mixture of peptides, called conopeptides. The venom is typically made up of 10 to 30 amino 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, using solid-phase peptide synthesis.
A component of the venom of Conus magus, ω-conotoxin, is now marketed as the analgesicziconotide, 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 to spinal cord injuries, and may be helpful in diagnosing and treating small cell carcinomas in the lung.
The biotechnology surrounding cone snails and their venom has promise for medical breakthroughs; with more than 50,000 conopeptides to study, the possibilities are numerous.[26]
See also
ConoServer, a database of cone snail toxins, known as conopeptides.[27] These toxins are of importance to medical research.
References
^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
