小塔螺科（學名：），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），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。由於本科物種皆屬於微小貝，相關研究少，物種間並不十分清楚，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。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。

分類
本科物種主要分為11個亞科（Ponder & Lindberg 1997）。An alternative interpretation is that the family Pyramidellidae is but one of six families within the superfamily Pyramidelloidea (Schander, van Aartsen & Corgan 1999). 
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。以下詳列自1997年以來多個分類間的差異。

1997年分類
在1997年的旁得和林德伯格的腹足類分類，本科的分類如下：
 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

1999年分類
Taxonomy of Pyramidellidae by Schander, Van Aartsen & Corgan (1999):
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

2005年分類
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：
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

往後分類的轉變
2010年，本科得到確認為單系群。

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。

，WoRMS紀錄小塔螺科包括下列各亞科與族：
 Subfamily Cyclostremellinae 
 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

有問題的分類元
The following genera are currently difficult to place within existing subtaxa of the Pyramidellidae.
 Charilda Iredale, 1929
 Contraxiala Laseron, 1956
 Cossmannica Dall & Bartsch, 1904
 Eulimotibera Nomura, 1939
 Morrisonetta Brandt, 1968
 Peristichia Dall, 1889
 Ulfa Dall & Bartsch, 1904
 Vagna Dall & Bartsch, 1904

The following species is of uncertain placement within Pyramidellidae.
 "Epigrus" insularis Oliver, 1915

異名
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

分佈
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。

型態描述
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.

習性
The Pyramidellidae are ectoparasites, feeding mainly on other molluscs and on annelid worms, but some are known to feed on peanut worms and crustaceans.
A few species in the family Pyramidellidae, such as Otopleura mitralis,  are symbiotic with sea anemones, such as Neoaiptasia morbilla.

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.

語源
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。
準確點說：這些物種都呈正圓錐體的模樣，又或是正多邊形的錐體。

參考文獻

延伸閱讀
 Dinapoli A., Zinssmeister C. & Klussmann-Kolb A. (2010). "New insights into the phylogeny of the Pyramidellidae (Gastropoda)". Journal of Molluscan Studies .

外部連結

 
 Gallery of pyramidellids