小塔螺科[2]（學名：Pyramidellidae），亦作尖塔螺科或簡單只叫塔螺科，是軟體動物門腹足綱下的一個科。舊屬腸紐目（Heterostropha，又譯異旋目）[2]，成員主要是營寄生生活的小型海螺。
小塔螺科的物種分佈於整個世界，有超過六千個不同的物種，合組成超過350個屬與亞屬[3]。由於本科物種皆屬於微小貝，相關研究少，物種間支序親緣關係並不十分清楚，大眾對於各物種的歸屬也沒有共識。舉例說：單單是 Schander (1999) 就列出了超過300個屬級以上的分類單元命名，並將這些分類單元整理[4]。由於近年本科在世界各地各個屬的分類未再有可一般化的修訂，這個科內各個分類單元仍然保持是多系群，也就是說這些分類的混亂還有一段時間。然而，從整個科來看仍然是個單系群[5]。
本科物種主要分為11個亞科（Ponder & Lindberg 1997）[6]。An alternative interpretation is that the family Pyramidellidae is but one of six families within the superfamily Pyramidelloidea (Schander, van Aartsen & Corgan 1999).[7]
當中有不少罕見或不常紀錄的物種。
本科之下的亞科在不同年代刊行的分類學文獻都有所不同，當中最為普遍的分類是2005年的布歇特和洛克羅伊的腹足類分類[8]。以下詳列自1997年以來多個分類間的差異。
在1997年的旁得和林德伯格的腹足類分類，本科的分類如下[6]：
- Chrysallidinae Saurin, 1958
- Cingulininae Saurin, 1959
- Cyclostremellinae Moore, 1966
- Eulimellinae Saurin, 1958
- Odostomellinae Saurin, 1959
- Odostomiinae Pelseneer, 1928
- Pyramidellinae J.E. Gray, 1840
- Sayellinae Wise, 1996
- Syrnolinae Saurin, 1958
- Tiberiinae Saurin, 1958
- Turbonillinae Bronn, 1849
Taxonomy of Pyramidellidae by Schander, Van Aartsen & Corgan (1999):[7]
- Superfamily Pyramidelloidea Gray, 1840
- Family Amathinidae Ponder, 1987
- Family Ebalidae Warén, 1994 - synonym: Anisocyclidae van Aartsen, 1995
- Family Odostomiidae Pelseneer, 1928
- Subfamily Odostomiinae Pelseneer, 1928
- Subfamily Chrysallidinae Saurin, 1958
- Subfamily Odostomellinae Saurin, 1958
- Subfamily Cyclostremellinae Moore, 1966
- Family Pyramidellidae J. E. Gray, 1840
- Subfamily Pyramidellinae J. E. Gray, 1840
- Subfamily Sayellinae Wise, 1996
- Family Syrnolidae Saurin, 1958
- Subfamily Syrnolinae Saurin, 1958
- Subfamily Tiberiinae Saurin, 1958
- Family Turbonillidae Bronn, 1849
- Subfamily Turbonillinae Bronn, 1849
- Subfamily Eulimellinae Saurin, 1958
- Subfamily Cingulininae Saurin, 1959
在2005年《布歇特和洛克羅伊的腹足類分類》，原來小塔螺總科之下的各科均被降級成為新的小塔螺科的亞科；而各科之下的亞科亦變成了各個亞科之下的族。這些變更總結如下[8]：
- Subfamily Pyramidellinae Gray, 1840
- Tribe Pyramidellini Gray, 1840 - synonyms: Obeliscidae A. Adams, 1863 (inv.); Plotiidae Focart, 1951 (inv.)
- Tribe Sayellini Wise, 1996 - formerly subfamily Sayellinae
- Subfamily Odostomiinae Pelseneer, 1928
- Tribe Odostomiini Pelseneer, 1928 - synonyms: Ptychostomonidae Locard, 1886; Liostomiini Schander, Halanych, Dahlgren & Sundberg, 2003 (n.a.)
- Tribe Chrysallidini Saurin, 1958 - formerly subfamily Chrysallidinae, synonyms: Menesthinae Saurin, 1958; Pyrgulininae Saurin, 1959
- Tribe Cyclostremellini D. R. Moore, 1966 - formerly subfamily Cyclostremellinae
- Tribe Odostomellini Saurin, 1959 - formerly subfamily Odostomellinae
- Subfamily Syrnolinae Saurin, 1958 - formerly subfamily Syrnolinae
- Tribe Syrnolini Saurin, 1958
- Tribe Tiberiini Saurin, 1958 - formerly subfamily Tiberiinae
- Subfamily Turbonillinae Bronn, 1849
- Tribe Turbonillini Bronn, 1849 - synonym: Chemnitziinae Stoliczka, 1868
- Tribe Cingulinini Saurin, 1958 - formerly subfamily Cingulininae
- Tribe Eulimellini Saurin, 1958 - formerly subfamily Eulimellinae
- Pyramidellidae incertae sedis
- Pyramidellidae incertae sedis insularis Oliver, 1915
- Pyrabinella Faber, 2013
2010年，本科得到確認為單系群[9]。
2017年，棲息於中南太平洋深海的塔螺總科新屬Helodiamea屬 Peñas & Rolán, 2017得到確認[10]。
截至2018年7月9日 (2018-07-09)[update]，WoRMS紀錄小塔螺科包括下列各亞科與族[11]：
- Subfamily Cyclostremellinae D. R. Moore, 1966
- Subfamily Odostomiinae Pelseneer, 1928
- Tribe Chrysallidini Saurin, 1958
- Tribe Cyclostremellini D. R. Moore, 1966
- Tribe Odostomiini Pelseneer, 1928
- Subfamily Pyramidellinae
- Tribe Pyramidellini Gray, 1840
- Tribe Sayellini Wise, 1996
- Subfamily Syrnolinae Saurin, 1958
- Tribe Syrnolini Saurin, 1958
- Tribe Tiberiini Saurin, 1958
- Subfamily Turbonillinae Bronn, 1849
The following genera are currently difficult to place within existing subtaxa of the Pyramidellidae.
- Charilda Iredale, 1929
- Contraxiala Laseron, 1956
- Cossmannica Dall & Bartsch, 1904[來源請求]
- Eulimotibera Nomura, 1939[來源請求]
- Morrisonetta Brandt, 1968[來源請求]
- Peristichia Dall, 1889[12]
- Ulfa Dall & Bartsch, 1904[來源請求]
- Vagna Dall & Bartsch, 1904[來源請求]
The following species is of uncertain placement within Pyramidellidae.
- "Epigrus" insularis Oliver, 1915
下列為本科分類單元的異名：
- Actaeopyramis P. Fischer, 1885: synonym of Monotigma G.B. Sowerby II, 1839
- Amaura Møller, 1842: synonym of Aartsenia Warén, 1991
- Auriculina Gray, 1847 accepted as Ondina de Folin, 1870
- Besla Dall & Bartsch, 1904 accepted as Parthenina Bucquoy, Dautzenberg & Dollfus, 1883
- Brachystomia Monterosato, 1884: synonym of Odostomia Fleming, 1813
- Chemnitzia d'Orbigny, 1839: synonym of Turbonilla Risso, 1826
- Elusa A. Adams, 1861: synonym of Tropaeas Dall & Bartsch, 1904
- Folinella Dall & Bartsch, 1904: synonym of Chrysallida Carpenter, 1856
- Iole A. Adams, 1860: synonym of Iolaea A. Adams, 1867
- Iolina Baily, 1948: synonym of Iolaea A. Adams, 1867
- Ividella Dall & Bartsch, 1909 accepted as Chrysallida Carpenter, 1856
- Lonchaeus : synonym of Longchaeus Mörch, 1875
- Moerchiella Thiele, 1924 : synonym of Moerchia A. Adams, 1860
- Moerchinella Thiele, 1931 accepted as Moerchia A. Adams, 1860
- Monoptygma: synonym of Monotigma G.B. Sowerby II, 1839
- Monotygma G.B. Sowerby II, 1839: synonym of Monotigma G.B. Sowerby II, 1839
- Noemia de Folin, 1870: synonym of Noemiamea de Folin, 1886
- Obeliscus Gray, 1847: synonym of Pyramidella Lamarck, 1799
- Obex Laws, 1940 accepted as Obexomia Laws, 1941
- Odontostoma Philippi, 1853: synonym of Odostomia Fleming, 1813
- Odontostomia G.B. Sowerby I, 1839: synonym of Odostomia Fleming, 1813
- Parthenia Lowe, 1840: synonym of Parthenina Bucquoy, Dautzenberg & Dollfus, 1883
- Parthenina Bucquoy, Dautzenberg & Dollfus, 1883: synonym of Chrysallida Carpenter, 1856
- Partulida Schaufuss, 1869: synonym of Chrysallida Carpenter, 1856
- Planipyrgiscus [sic] accepted as Planpyrgiscus Laws, 1937
- Plotia Röding, 1798: synonym of Pyramidella Lamarck, 1799
- Ptychostomon Locard, 1886 accepted as Odostomia Fleming, 1813
- Pyrgulina A. Adams, 1864: synonym of Chrysallida Carpenter, 1856
- Raoulostraca Oliver, 1915 accepted as Eulimella Forbes & M'Andrew, 1846
- Tragula Monterosato, 1884: synonym of Chrysallida Carpenter, 1856
- Tropeas [sic] accepted as Tropaeas Dall & Bartsch, 1904
本物種有世界性分佈，但當中不少物種都只在相當細小範圍內分佈。在佛得角的各物種均為當地的特有種[13]。
The length of the slender, elongated (turreted or conical) shells varies between 0.5 mm and 3.5 cm, but most species in the family have shells which are smaller than 13 mm.
The texture of these shells is smooth or sculptured in various forms such as ribs and spirals. Their color is mostly white, cream or yellowish, sometimes with red or brown lines.
The shell of these snails has a blunt, heterostrophic (i.e. whorls appear to be coiled in the opposite direction to those of the teleoconch) protoconch, which is often pointed sideways or wrapped up. The teleoconch is dextrally coiled, but the larval shells are sinistral. This results in a sinistrally coiled protoconch.
The columella has usually one, but sometimes several, spiral folds. The aperture is closed by an operculum.
The operculum is ovoid and paucispiral, with the apex anterior, a thread-like arcuate ridge on the proximal side, the inner margin notched in harmony with the plaits of the pillar when prominent.
The Pyramidellidae are ectoparasites, feeding mainly on other molluscs and on annelid worms, but some are known to feed on peanut worms and crustaceans.[14][15]
A few species in the family Pyramidellidae, such as Otopleura mitralis, are symbiotic with sea anemones, such as Neoaiptasia morbilla.[16]
They do not have a radula. Instead their long proboscis is used to pierce the skin of its prey and suck up its fluids and soft tissues. The eyes on the grooved tentacles are situated toward the base of the tentacles. These tentacles have a concave surface. Between the head and the propodium (the foremost division of the foot), a lobed process called the mentum (= thin projection) is visible. This mentum is slightly indented in midline.
These gastropods are hermaphrodites, laying eggs in jelly-like masses on the shell of its host. Some species have spermatophores.[4][17][18]
本科的學名源於金字塔的英語pyramid，而這亦是這些物種普遍的外型[19]。
準確點說：這些物種都呈正圓錐體的模樣[20]，又或是正多邊形的錐體[21]。
Gray, J. E. Synopsis of the contents of the British Museum, 42nd edition. London. 1840: 370 pp.
Schander, Christoffer; Hori, Shigeo; Lundberg, Joakim. Anatomy, phylogeny and biology of Odostomella and Herviera, with the description of a new species of Odostomella (Mollusca, Heterostropha, Pyramidellidae). Ophelia. 2011, 51 (1): 39–76. doi:10.1080/00785326.1999.10409399. Dinapoli, A.; Zinssmeister, C.; Klussmann-Kolb, A. New insights into the phylogeny of the Pyramidellidae (Gastropoda). Journal of Molluscan Studies. 2010, 77 (1): 1–7. doi:10.1093/mollus/eyq027. Ponder, Winston; Lindberg, David R. Towards a phylogeny of gastropod molluscs; an analysis using morphological characters. Zoological Journal of the Linnean Society. 1997, 119 (2): 83–265. doi:10.1111/j.1096-3642.1997.tb00137.x （英語）. Bieler R, Bouchet P, Gofas S, Marshall B, Rosenberg G, La Perna R, Neubauer TA, Sartori AF, Schneider S, Vos C, ter Poorten JJ, Taylor J, Dijkstra H, Finn J, Bank R, Neubert E, Moretzsohn F, Faber M, Houart R, Picton B, Garcia-Alvarez O (編). Pyramidellidae Gray, 1840. MolluscaBase. [2018-07-14] –透過WoRMS. Sneli, J.-A. Odostomia turrita found on Hommarus gammarus. Nautilus. 1972, 86 (1): 23–24.
Høisæter, T. Spermatophores in Chrysallida obtusa (Brown) (Opisthobranchia, Pyramidellidae). Sarsia. 1965, 18: 63–68.
Robertson, R. The life history of Odostomia bisuturalis and Odostomia spermatophores (Gastropoda: Pyramidellidae). American Philosophical Society Yearbook. 1967, 1967: 368–370.
Robbins, Edward. [小塔螺科載於Google圖書 Plane and Solid Geometry]. American Book Company. 1907: 349 （英語）.
- Dinapoli A., Zinssmeister C. & Klussmann-Kolb A. (2010). "New insights into the phylogeny of the Pyramidellidae (Gastropoda)". Journal of Molluscan Studies doi:10.1093/mollus/eyq027.
- Hayward P. J. &, J.S. Ryland. Handbook of the Marine Fauna of North-West Europe. Oxford University Press. 1996: 546. ISBN 0-19-854055-8.
