Fissurellidae


Fissurellidae, commonly called keyhole limpets or slit limpets, is a taxonomic family of small to medium-sized limpet-like sea snails, marine gastropod molluscs in the clade Vetigastropoda.
Their common name derives from the small hole in the apex of their cone-like shells. Although superficially resembling "true" limpets, they are in fact not closely related to them.

Distribution

The distribution of fissurellids is worldwide, from cold waters to tropical waters.

Habitat

Fissurellids live in habitats on and under rocks in the lower intertidal zones to deeper waters.

Shell description

Keyhole limpets somewhat resemble true limpets because of the simple conical shape of their shells, but in reality they are not closely related to true limpets, which are in the clade Patellogastropoda.
This conical shape and the low profile of the shell allow keyhole limpets to withstand wave attack on exposed rocks to which they attach firmly with their strong, muscular foot.
The shell may vary in color and pattern. The shell has a reticulate structure with strong radial ribs and lacks an operculum.
The shell ranges from 3 mm to 13.2 cm. The great keyhole limpet measures up to 13.2 cm.
For respiration, the shells of fissurellids have a single apical or subapical perforation. This opening at the top allows a direct exit of exhalant water currents together with waste products from the mantle cavity. The water enters under the edge of the shell near the head and passes over large paired gills. Most young species in this family have a marginal slit in the middle of the anterior end of the spiral shell. Some species possess just a short internal groove at the anterior end. The paired organs in the mantle cavity represent a primitive condition in gastropods.
The soft body consists of a well-developed head, a short muzzle. It has a broad and flat foot and a well-developed mantle. This foot exerts a strong suction, adhering the keyhole limpet to its hard substratum. The mantle extends in some species partly or completely over the shell. The tentacles at the epipodium are well developed. The species in Medusafissurella have numerous subequal tentacles at the propodium, while the species in Dendrofissurella'' have an outgrowth with main trunk and side branches at the propodium. The eyes are situated on rudimentary pedicels at their outer bases. The sides are ornamented with short cirri. There are two, symmetrical branchial plumes. The anal siphon occupies the anterior notch or perforated summit of the shell.
In addition to the possession of this hole, slit or groove, keyhole limpets differ in several other ways both internally and externally from true limpets.

Feeding habits

Keyhole limpets are in essence herbivorous, feeding primarily on algae, but are also detritus feeders. They play an important role in marine ecosystems by controlling the growth of algae on rocky substrates.
A few species in the genera Diodora and Emarginella are carnivorous, feeding on sponges. Puncturella has been reported to digest diatoms and detritus. Puncturella aethiopica feeds mainly on Foraminifera.
They are also prey for various marine animals, including starfish and some mollusk-eating birds.

Taxonomy

Family Fissurellidae Fleming, 1822
This classification was based by Bouchet & Rocroi on the studies by Keen, Christiaens and McMean.
Aktipis S.W., Boehm E. & Giribet G. then raised the tribe Diodorini to the status of subfamily Diodorinae.

Genera

Genera within the family Fissurellidae include:Agariste Monterosato, 1892Altrix Palmer, 1942Amblychilepas Pilsbry, 1890Buchanania Lesson, 1830Clathrosepta McLean & Geiger, 1998Clypidina Gray, 1847Cornisepta McLean & Geiger, 1998Cosmetalepas Iredale, 1924 Cranopsis Adams (zoologist)|Adams], 1860Dendrofissurella Mclean and Kilburn, 1986Diodora Gray, 1821Emarginula Lamarck, 1801Fissurella Bruguière, 1789Fissurellidea d'Orbigny, 1841Fissurisepta Seguenza, 1863Hemimarginula McLean, 2011Hemitoma Swainson, 1840Laeviemarginula Habe In Kuroda, 1953Laevinesta Pilsbry and McGinty, 1952Leurolepas J. H. McLean, 1970Lucapina Sowerby II|Sowerby], 1835Lucapinella Pilsbry, 1890Macroschisma Sowerby, 1839Manganesepta McLean & Geiger, 1998Medusafissurella Mclean and Kilburn, 1986Megathura Pilsbry, 1890Monodilepas Finlay, 1927Montfortia Récluz, 1843Montfortista Iredale, 1929Montfortula Iredale, 1915Montfortulana Habe, 1961Nesta Adams, 1870Octomarginula McLean, 2011Parmaphorella Strebel, 1907Profundisepta McLean & Geiger, 1998Puncturella R. T. Lowe, 1827Pupillaea Gray In Sowerby, 1835Rimula DeFrance, 1827Rimulanax Iredale, 1924 Scelidotoma Choe, Yoon and Habe, 1992Scutus Montfort, 1810Stromboli Berry, 1954Tugali Gray in Dieffenbach, 1843Tugalina Habe, 1953Vacerrena Iredale, 1958Variemarginula McLean, 2011Zeidora A. Adams, 1860
; Genera brought into synonymy:Austroglyphis Cotton & Godfrey, 1934: synonym of Diodora Gray, 1821Aviscutum Iredale, 1940: synonym of Scutus Montfort, 1810Capiluna Gray, 1857: synonym of Diodora Gray, 1821Cemoria Risso, 1826 : synonym of Puncturella Lowe, 1827Cremoria : synonym of Puncturella Lowe, 1827Elegidion Iredale, 1924: synonym of Diodora J. E. Gray, 1821Emarginella Pilsbry, 1890: synonym of Emarginula Lamarck, 1801Entomella Cotton, 1945: synonym of Emarginula Lamarck, 1801Fissuridea Swainson, 1840: synonym of Diodora J. E. Gray, 1821Glyphis Carpenter, 1857: synonym of Diodora J. E. Gray, 1821Legrandia Beddome, 1883: synonym of Zeidora A. Adams, 1860Megatebennus Pilsbry, 1890: synonym of Fissurellidea d'Orbigny, 1839Nannoscutum Iredale, 1937: synonym of Scutus Montfort, 1810Nesta H. Adams, 1870: synonym of Zeidora A. Adams, 1860Notomella Cotton, 1957: synonym of Emarginula Lamarck, 1801Parmophoridea Wenz, 1938: synonym of Parmaphorella Strebel, 1907Parmophorus Blainville, 1817: synonym of Scutus Montfort, 1810Plagiorhytis P. Fischer, 1885: synonym of Montfortula Iredale, 1915Scutum P. Fischer, 1885: synonym of Scutus Montfort, 1810Semperia Crosse, 1867: synonym of Emarginula Lamarck, 1801Sipho T. Brown, 1827: synonym of Puncturella Lowe, 1827Siphonella Issel, 1869: synonym of Montfortista Iredale, 1929Subemarginula Gray, 1847: synonym of Hemitoma Swainson, 1840Subzeidora Iredale, 1924: synonym of Emarginula Iredale, 1924Tugalia Gray, 1857: synonym of Tugali Gray, 1843Vacerra Iredale, 1924: synonym of Puncturella Lowe, 1827Zidora P. Fischer, 1885: synonym of Zeidora A. Adams, 1860

General references

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