Caecum is a genus of minute sea snails, marine gastropod micromolluscs or micromollusks in the family Caecidae or blind shells.
Distribution This genus occurs worldwide in warm and temperate seas. Many species live in sponges, in sandy spots on reefs, or in grassy beds in shallow waters in bays and lagoons. Some species are very common and can be extremely numerous where they do occur, such as the "beautiful caecum" (Caecum pulchellum), but even they can be easily overlooked as they are so tiny. Many species are considered to be uncommon, but this assessment may be a result of lack of proper sampling.
Shell description The shells in this genus, like the others in the family, are very small with a length between 2 mm and 6 mm. Their colour is white to yellowish white and some are almost translucent. They are unusual in that the teleoconch of the adult shell is a curving tube for most of its length. In the first stage of the shell it is spiral-shaped but soon becomes cylindrical. The shell is sealed with a permanent calcareous plug at one end and (when the animal has withdrawn into the shell) with a circular, multispiral, horny operculum at the other end, the shell aperture. The sculpture is smooth or consists of a close-set, large number of annular ridges. Feeding habits These snails feed on one-celled organisms on sand grains or pebbles.
Species Species in the genus Caecum include:
† Caecum aartseni Van Dingenen, Ceulemans & Landau, 2016 Caecum achirona (de Folin, 1867) Caecum adamsi Raines, 2020 Caecum amputatum Ch. Hedley, 1894 Caecum amydroglyptum Rehder, 1980 Caecum angustum de Folin, 1879 Caecum annulatum Emmons, 1858 Caecum antillarum Carpenter, 1858 - Antillean caecum Caecum arabicum Issel, 1869 Caecum armoricum de Folin, 1869 - De Folin's lagoon snail. This species is fully protected in the United Kingdom under the Wildlife and Countryside Act 1981 since 1992.Protection for wild animals on Schedule 5 of the Wildlife and Countryside Act, 1981. website accessed 7 August 2009. Caecum atlantidis R. B. Watson, 1897 Caecum attenuatum de Folin, 1879 Caecum auriculatum de Folin, 1868 Caecum austrafricanum Vannozzi, Pizzini & Raines, 2015 Caecum australe Pizzini & Raines, 2011 Caecum bathus Pizzini, Raines & Vannozzi, 2013 † Caecum benhami Goedert & Raines, 2016 † Caecum bensoni Goedert & Raines, 2016 Caecum beaufortensis Ward and Blackwelder 1987 Caecum bimamillatum de Folin, 1867 Caecum bimarginatum Carpenter, 1859 Caecum biomaglo Vannozzi, 2023 Caecum bipartitum de Folin, 1870 Caecum borneoense de Folin, 1867 Caecum bounty Pizzini & Raines, 2011 Caecum brasilicum de Folin, 1874 Caecum brennani Raines & Pizzini, 2009 Caecum breve de Folin, 1867 Caecum bucerium Golikov, 1967 Caecum californicum Dall, 1885 - California caecum Caecum calvertense Martin, 1904 Caecum campanulatum Raines & Pizzini, 2005 Caecum campe Pilsbry and Olsson, 1941 Caecum carolinianum Dall, 1892 - Carolina caecum † Caecum carpenteri Deshayes, 1861 Caecum caverna Moolenbeek, Faber & Iliffe, 1989 Caecum chilense Stuardo, 1962 Caecum chinense de Folin, 1879 Caecum chipolanum Gardner, 1947 Caecum cinctum Olsson & Harbison, 1953 Caecum circumvolutum de Folin, 1867 Caecum clarkii P. P. Carpenter, 1858 Caecum clarum Lamy, 1910 [ex de Folin MS] Caecum clathratum P. P. Carpenter, 1857 Caecum clava de Folin, 1867 - club caecum Caecum cocoense Sibaja-Cordero, García-Méndez & Troncoso, 2013 Caecum codoceoae Gálvez & Huidobro, 2017 Caecum condylum Moore, 1969 - bone caecum Caecum continens Van der Linden & Moolenbeek, 2000 Caecum cooki Pizzini & Raines, 2011 Caecum cooperi S. I. Smith, 1860 - Cooper's Atlantic caecum Caecum corrugatulum Carpenter, 1857 Caecum crassum de Folin, 1870 Caecum crebricinctum Carpenter, 1864 - many-named caecum Caecum crispum A. E. Verrill & Bush, 1900 Caecum crystallinum de Folin, 1880 Caecum cubitatum (de Folin, 1868) - smooth caecum Caecum cuspidatum Chaster, 1896 Caecum cycloferum de Folin, 1867 - fatlip caecum Caecum dakuwaqa Pizzini, Raines & Vannozzi, 2013 Caecum dalli Bartsch, 1920 Caecum danielei Pizzini & Raines, 2011 Caecum debile A. E. Verrill & Bush, 1900 Caecum delicatulum A. E. Verrill & Bush, 1900 Caecum derjugini Golikov, 1967 Caecum dextroversum P. P. Carpenter, 1858 Caecum digitulum Hedley, 1904 Caecum diminutum C. B. Adams, 1852 Caecum directum Vannozzi, 2019 Caecum donmoorei Mitchell-Tapping, 1979 Caecum draperi Raines, 2020 Caecum dux de Folin, 1871 Caecum eburneum C. B. Adams, 1852 Caecum egenum Vannozzi, 2017 Caecum elegantissimum Carpenter, 1859 Caecum eliezeri Absalao, 1997 Caecum elongatum P. P. Carpenter, 1857 Caecum engli Nofroni, Pizzini, Oliverio, 1997 Caecum eunoi Nofroni, Pizzini, Oliverio, 1997 Caecum exile de Folin, 1875 Caecum farcimen P. P. Carpenter, 1857 Caecum fijiense Pizzini, Raines & Vannozzi, 2013 Caecum firmatum C. B. Adams, 1852 Caecum floridanum Stimpson, 1851 - Florida caecum Caecum folini Kisch, 1959 Caecum frugi Vannozzi, 2019 Caecum galapagoense Raines, 2020 Caecum geigeri Pizzini & Raines, 2011 Caecum glabellum A. Adams, 1868 Caecum glabriforme Carpenter, 1857 Caecum glabrum (Montagu, 1803) Caecum gofasi Pizzini & Nofroni, 2001 Caecum granulatum Vannozzi, 2019 Caecum greensboroense Martin, 1904 Caecum gulosum Hedley, 1899 Caecum gurgulio Carpenter, 1858 - windpipe caecum Caecum hemphilli Bartsch, 1920 Caecum heptagonum (Bartsch, 1920) Caecum heterochromum Raines & Pizzini, 2005 Caecum hyalinum Vannozzi, 2022 Caecum imbricatum Carpenter, 1858 - imbricate caecum Caecum incisum Vannozzi, Pizzini & Raines, 2015 Caecum imperforatum Kanamacher, 1798 (nomen dubium) Caecum inclinatum de Folin, 1869 Caecum infimum de Folin, 1867 Caecum inflatulum Vannozzi, 2017 Caecum inflatum de Folin, 1867 Caecum inhacaense Albano & Pizzini 2011Albano, P.G. & Pizzini, M. 2011. Notes on Caecidae (Mollusca: Gastropoda) from southern Mozambique, with the description of a new species. African Invertebrates 52 (1): 1-10. Caecum insculptum Carpenter, 1857 Caecum insularum Moore, 1969 Caecum intortum Vannozzi, Pizzini & Raines, 2015 Caecum invisibile Egger & Jörger, 2020 Caecum iricolor Vannozzi, 2023 Caecum japonicum (Habe, 1978) Caecum johnsoni Winkley, 1908 Caecum jonatani Espinosa, Ortea & Fernandez-Garcés, 2007 Caecum jonesae Swinnen & Simone, 2024 Caecum jucundum de Folin, 1867 Caecum knysnaense Vannozzi, Pizzini & Raines, 2015 Caecum kontiki Pizzini & Raines, 2011 Caecum laeve C.B. Adams, 1852 Caecum lapita Pizzini, Raines & Vannozzi, 2013 Caecum laqueatum C. B. Adams, 1852 † Caecum larieyense Lozouet, Lesport & Renard, 2001 Caecum leilae Vannozzi, Pizzini & Raines, 2015 Caecum lightfootanum Raines, 2020 Caecum limnetes Long, 1972 Caecum limpidum de Folin, 1874 Caecum lindae Vannozzi, Pizzini & Raines, 2015 Caecum lineicinctum de Folin, 1880 Caecum liratocinctum Carpenter, 1857 Caecum lohri Strong & Hertlein, 1939 Caecum loyaltense Pizzini, Raines & Vannozzi, 2013 Caecum lozoueti Vannozzi & Renda, 2024 Caecum lucidum de Folin, 1867 Caecum macrum Van der Linden & Moolenbeek, 2000 Caecum maestratii Pizzini, Raines & Vannozzi, 2013 Caecum magellanicum di Geronimo, Privitera & Valdovinos, 1995 Caecum malleatum de Folin, 1867 † Caecum mammillatum S. V. Wood, 1848 Caecum maori Pizzini & Raines, 2006 Caecum maraisi Vannozzi, Pizzini & Raines, 2015 Caecum marginatum de Folin, 1869 Caecum marmoratum de Folin, 1869 Caecum massambabense Absalao, 1994 Caecum mauritianum de Folin, 1867 Caecum metamorphosicum S. Lima, Santos & Absalão, 2013 Caecum microannulatum Vannozzi & Renda, 2024 Caecum microstriatum Pizzini, Raines & Vannozzi, 2013 Caecum miliarium Vannozzi & Renda, 2024 † Caecum mineuri Lozouet, 1999 Caecum mirificum de Folin, 1867 Caecum modestum de Folin, 1867 Caecum monstrosum C. B. Adams, 1852 Caecum moorei (Marincovich, 1973) Caecum morgan Vannozzi, Pizzini & Raines, 2015 Caecum multicostatum de Folin, 1867 Caecum musorstomi Pizzini, Raines & Vannozzi, 2013 Caecum nasutum Vannozzi, 2019 † Caecum nemoralis Lozouet, 2015 Caecum neocaledonicum de Folin, 1867 Caecum neoguineanum Vannozzi, 2019 Caecum nofronii Vannozzi, 2019 Caecum oahuense H. A. Pilsbry, 1921 Caecum obtusum Carpenter, 1857 Caecum occidentale (Bartsch, 1920) - western caecum Caecum orcutti (Dall, 1885) Caecum paradoxum de Folin, 1867 Caecum parvum C. B. Adams, 1852 Caecum pascuanum Raines & Pizzini, 2005 † Caecum pertenuis Laws, 1941 Caecum planum de Folin, 1874 Caecum patuxentium Martin, 1904 Caecum plicatum Carpenter, 1858 - plicate caecum Caecum pollicare Carpenter, 1859 Caecum praegrande Vannozzi, 2017 Caecum profundicolum Bartsch, 1920 - deepwater caecum Caecum properegulare Mansfield, 1925 Caecum pulchellum Stimpson, 1851 - beautiful caecum Caecum pygmaeum C. B. Adams, 1852 Caecum quadratum P. P. Carpenter, 1857 Caecum rapanuiense Raines & Pizzini, 2005 Caecum regulare Carpenter, 1858 Caecum rehderi Raines & Pizzini, 2005 Caecum restrictum Vannozzi & Renda, 2024 Caecum reversum Carpenter, 1857 Caecum richthofeni A. M. Strong & J. G. Hertlein, 1939 Caecum rijgersmai Jong & Coomans, 1988 † Caecum roederi Raines, C. L. Powell & LaFollette, 2023 Caecum rolani Pizzini & Nofroni, 2001 Caecum rosanum Bartsch, 1920 Caecum rostratum de Folin, 1881 Caecum ruggerii Pizzini, 1997 Caecum rugulosum Phil, 1836 Caecum ryssotitum de Folin, 1867 - minute caecum Caecum searleswoodii Carpenter, 1859 Caecum semilaeve Carpenter, 1857 Caecum senegambianum de Folin, 1870 Caecum sepimentum de Folin, 1868 Caecum shaskyi Raines, 2020 Caecum simplicissimum Thiele, 1925 Caecum sinuatum de Folin, 1867 Caecum skoglundae Pizzini, Raines & Nofroni, 2007 Caecum smriglioi Pizzini, Nofroni & Bonfitto, 2008 Caecum someri (de Folin, 1867) Caecum spiculum Raines, 2020 Caecum striatum de Folin, 1875 Caecum strictum de Folin, 1871 Caecum strigosum de Folin, 1868 Caecum subannulatum de Folin, 1870 Caecum subaustrale Stuardo, 1970 Caecum subconicum Carpenter, 1857 Caecum subcylindratum Pizzini, Raines & Vannozzi, 2013 Caecum subflavum de Folin, 1879 Caecum subimpressum P. P. Carpenter, 1857 Caecum subobsoletum Carpenter, 1857 Caecum subornatum de Folin, 1874 Caecum subspirale Carpenter, 1857 Caecum subquadratum Carpenter, 1859 Caecum subspirale Carpenter, 1857 Caecum subvolutum de Folin, 1874 Caecum succineum de Folin, 1879 Caecum swinneni Nofroni, Pizzini, Oliverio, 1997 Caecum taeniatum de Folin, 1869 Caecum tahitianum Pizzini & Raines, 2011 Caecum temporale Vannozzi & Renda, 2024 Caecum tenue Verrill & Bush, 1900 Caecum tenuicostatum de Folin, 1881 Caecum tenuiliratum Carpenter, 1857 † Caecum tenuistriatum O. Boettger, 1869 Caecum teres Carpenter, 1857 Caecum textile de Folin, 1867 - textile caecum Caecum tornatum A. E. Verrill & Bush, 1900 Caecum torquetum de Folin, 1867 Caecum tortile Dall, 1892 - twisted caecum Caecum trachea G. Montagu, 1803 Caecum trindadense S. Lima, Santos & Absalão, 2013 Caecum troglodyta Moolenbeek, Faber & Iliffe, 1989 † Caecum tumidum Carpenter, 1858 Caecum uncinatum de Folin, 1867 Caecum undatum P. P. Carpenter, 1857 Caecum vanuatuarum Pizzini, Raines & Vannozzi, 2013 Caecum varanoi Pizzini, Nofroni & Bonfitto, 2008 Caecum variegatum de Folin, 1867 Caecum venosum de Folin, 1867 † Caecum verai Moreno, Peñas & Rolán, 2003 Caecum vertebrale Ch. Hedley, 1899 Caecum vicinum de Folin, 1870 Caecum virginiae Pizzini, Raines & Vannozzi, 2013 Caecum vitreum P. P. Carpenter, 1858 Caecum wakense Raines & Vannozzi, 2024 Caecum wami Raines & Pizzini, 2009 Caecum wayae Pizzini & Nofroni, 2001 Caecum zaagmani Jong and Coomans, 1988
Subgenera brought into synonymy Caecum (Defolinia) Weisbord, 1962: synonym of Caecum Fleming, 1813