Editing Gastropoda (section)

== Diversity ==
At all [[Taxonomy (biology)|taxonomic]] levels, gastropods are second only to insects in terms of their [[Biodiversity|diversity]].<ref>{{cite book|chapter=Molecular systematics of the major lineages of the Gastropoda. |pages =140–160 |title= Molecular Systematics and Phylogeography of Mollusks|author=McArthur, A.G. |author2=M.G. Harasewych|year=2003|editor1=C. Lydeard |editor2= D.R. Lindberg|location= Washington|publisher= Smithsonian Books}}</ref>

Gastropods have the greatest numbers of named [[Mollusca|mollusk]] species. However, estimates of the total number of gastropod species vary widely, depending on cited sources. The number of gastropod species can be ascertained from estimates of the number of described species of Mollusca with accepted names: about 85,000 (minimum 50,000, maximum 120,000).<ref name="Chapman 2009">Chapman, A.D. (2009). [http://www.environment.gov.au/biodiversity/abrs/publications/other/species-numbers/2009/04-02-groups-invertebrates.html#mollusca Numbers of Living Species in Australia and the World, 2nd edition] {{Webarchive|url=https://web.archive.org/web/20101206050101/http://www.environment.gov.au/biodiversity/abrs/publications/other/species-numbers/2009/04-02-groups-invertebrates.html#mollusca |date=2010-12-06 }}. Australian Biological Resources Study, Canberra. Accessed 12 January 2010. {{ISBN|978-0-642-56860-1}} (printed); {{ISBN|978-0-642-56861-8}} (online).</ref> But an estimate of the total number of Mollusca, including undescribed species, is about 240,000 species.<ref>Appeltans W., Bouchet P., Boxshall G.A., Fauchald K., Gordon D.P., Hoeksema B.W., Poore G.C.B., van Soest R.W.M., Stöhr S., Walter T.C., Costello M.J. (eds) (2011). World Register of Marine Species. Accessed at [http://www.marinespecies.org marinespecies.org] {{Webarchive|url=https://archive.today/20151003132733/http://www.marinespecies.org/ |date=2015-10-03 }} on 2011-03-07.</ref> The estimate of 85,000 mollusks includes 24,000 described species of terrestrial gastropods.<ref name="Chapman 2009"/>

Different estimates for aquatic gastropods (based on different sources) give about 30,000 species of marine gastropods, and about 5,000 species of freshwater and [[Brackish water|brackish]] gastropods. Many deep-sea species remain to be discovered, as only 0.0001% of the deep-sea floor has been studied biologically.<ref>{{Cite web|url=http://www.comlsecretariat.org/wp-content/uploads/2010/06/SYNDEEP-Towards-a-first-global-synthesis-of-biodiversity-biogeography-and-ecosystem-function-in-the-deep-sea-Eva-Ramirez-Llodra-et-al..pdf|title=Census of Marine Life (2012). SYNDEEP: Towards a first global synthesis of biodiversity, biogeography and ecosystem function in the deep sea. Unpublished data (datasetID: 59)|access-date=2019-04-25|archive-url=https://web.archive.org/web/20190630235926/https://www.comlsecretariat.org/wp-content/uploads/2010/06/SYNDEEP-Towards-a-first-global-synthesis-of-biodiversity-biogeography-and-ecosystem-function-in-the-deep-sea-Eva-Ramirez-Llodra-et-al..pdf|archive-date=2019-06-30|url-status=usurped}}</ref><ref name="britannica 2010">[https://www.britannica.com/EBchecked/topic/226777/gastropod "gastropod"] {{Webarchive|url=https://web.archive.org/web/20081013064413/https://www.britannica.com/EBchecked/topic/226777/gastropod |date=2008-10-13 }}. (2010). In Encyclopædia Britannica. Retrieved March 05, 2010, from Encyclopædia Britannica Online.</ref> The total number of living species of freshwater snails is about 4,000.<ref name="Strong 2008">{{cite journal|hdl=10088/7390|doi=10.1007/s10750-007-9012-6|title=Global diversity of gastropods (Gastropoda; Mollusca) in freshwater|date=January 2008 |last1=Strong|first1=Ellen E.|last2=Gargominy|first2=Olivier|last3=Ponder|first3=Winston F.|last4=Bouchet|first4=Philippe|journal=Hydrobiologia|volume=595|issue=1 |pages=149–166|bibcode=2008HyBio.595..149S |s2cid=44234861}}</ref>

Recently [[extinct]] species of gastropods (extinct since 1500) number 444, 18 species are now [[extinct in the wild]] (but still exist in captivity), and 69 species are "possibly extinct".<ref name="Régnier 2009">{{Cite journal
| last1 = Régnier | first1 = C.
| last2 = Fontaine | first2 = B. T.
| last3 = Bouchet | first3 = P.
| s2cid = 8021609
| doi = 10.1111/j.1523-1739.2009.01245.x
| title = Not Knowing, Not Recording, Not Listing: Numerous Unnoticed Mollusk Extinctions
| journal = Conservation Biology
| volume = 23
| issue = 5
| pages = 1214–1221
| date = October 2009
| pmid = 19459894
| bibcode = 2009ConBi..23.1214R
}}</ref>

The number of prehistoric (fossil) species of gastropods is at least 15,000 species.<ref>{{in lang|es}} Nájera J. M. (1996). "Moluscos del suelo como plagas agrícolas y cuarentenarias". ''X Congreso Nacional Agronómico / II Congreso de Suelos 1996'' 51-56. [http://www.bio-nica.info/biblioteca/Monje1996.pdf PDF] {{Webarchive|url=https://web.archive.org/web/20110721191146/http://www.bio-nica.info/biblioteca/Monje1996.pdf |date=2011-07-21 }}</ref>

In marine habitats, the [[continental slope]] and the [[continental rise]] are home to the highest diversity, while the continental shelf and abyssal depths have a low diversity of marine gastropods.<ref>{{Cite journal|last=Rex|first=Michael A.|date=1973-09-14|title=Deep-Sea Species Diversity: Decreased Gastropod Diversity at Abyssal Depths|journal=Science|language=en|volume=181|issue=4104|pages=1051–1053|doi=10.1126/science.181.4104.1051|issn=0036-8075|pmid=17731267|bibcode=1973Sci...181.1051R|s2cid=43572097}}</ref>