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True limpets are marine gastropods with flattened, cone-shaped shells in the order Patellogastropoda in the subclass Eogastropoda, the other subclass of Gastropoda, along with Orthogastropoda.

Limpets live throughout the intertidal zone, from the high zone (upper littoral) to the shallow subtidal on the rocky coasts of most oceans. Limpets can be commonly found attached to rocks, looking like little disks or bumps on the rock surface. They attach themselves to the substratum using pedal mucus and a muscular "foot," which enables them to remain attached through dangerous wave action and which also seals against the rock to protect from desiccation during low tide.

Limpets forage by grazing on algae found on rock surfaces. They scrape films of algae from the rock with a radula. Limpets move by rippling the muscles of their foot in a wave-like motion.

Some limpets have a hole at the top, through which gaseous exchange can occur. Most limpets are less than 3 inches (8 centimeters) long, but a West Mexican Limpet grows to be 8 inches (20 centimeters).

Limpets found on sheltered shores (limpets that are less frequently in contact with wave action, and thus less frequently in contact with water) have a greater risk of desiccation due to the effects of sunlight, water evaporation, and the wind. To avoid drying out they will clamp to the rock they inhabit, minimizing water-loss from the rim around their base. As this occurs chemicals are released that promote the vertical growth of the limpet's shell.

Some species of limpets exhibit homing behavior, returning to the same spot on the rock, known as a "home scar," just before the tide recedes. In such species, the shape of their shell often grows to precisely match the contours of the rock surrounding the scar. This behavior presumably allows them to form a better seal to the rock and may help protect from either predation or desiccation. It is still unclear how limpets find their way back to the same spot each time, but it is thought that they follow a mucus trail left as they move, and utilize their tentacles.

Other species, notably Lottia gigantea seem to "garden" a patch of algae around their home scar. They will aggressively push other organisms out of this patch by ramming with their shell, thereby allowing their patch of algae to grow for their own grazing. Also, where the limpets eat the algae off of bare rocks, it causes places where other organisms can grow and thrive.

Limpets are preyed upon by a variety of organisms including starfish, shore-birds, fish, seals, and humans. Limpets exhibit a variety of defenses, such as fleeing or clamping their shells against the substratum. The defense response can be determined by the type of predator, which can often be detected chemically by the limpet.

Limpets can be long lived, with tagged specimens surviving for more than ten years.

Taxonomy

The taxonomy of the Gastropoda is under constant revision, but more and more of the old taxonomy is being abandoned. In a sense, we can speak of a taxonomic jungle when we go down to the lower taxonomic levels. The taxonomy of the Gastropoda can be different from author to author. With the arrival of DNA-sequencing, further revisions of the higher taxonomic levels are to be expected in the near future.

The traditional classification recognized four subclasses. :

  • Prosobranchia (gills in front of the heart).
  • Opisthobranchia (gills to the right and behind the heart).
  • Gymnomorpha (no shell)
  • Pulmonata (with lungs instead of gills)

According to the newest insights (Ponder & Lindberg, 1997), the taxonomy of the Gastropoda should be rewritten in terms of strictly monophyletic groups. They recognize the subclasses of Orthogastropoda and Eogastropoda.

Integrating new findings into a working taxonomy will be a true challenge in the coming years. At present, it is impossible to give a classification of the Gastropoda that has consistent ranks and also reflects current usage. Convergent evolution, observed at especially high frequency in the Gastropods, may account for the observed differences between phylogenies obtained from morphological data and more recent studies based on gene sequences.

Proposed classification, down to the level of superfamily

Class Gastropoda (Cuvier, 1797)
Incertæ sedis

  • Order Bellerophontida (fossil)
  • Order Mimospirina (fossil)

Subclass Eogastropoda (Ponder & Lindberg, 1996) (earlier: Prosobranchia)

  • Order Euomphalida de Koninck 1881 (fossil)
      • Superfamily Macluritoidea
      • Superfamily Euomphaloidea
      • Superfamily Platyceratoidea
  • Order Patellogastropoda Lindberg, 1986 (true limpets)
    • Suborder Patellina Van Ihering, 1876
      • Superfamily Patelloidea Rafinesque, 1815
    • Suborder Nacellina Lindberg, 1988
      • Superfamily Acmaeoidea Carpenter, 1857
      • Superfamily Nacelloidea Thiele, 1891
    • Suborder Lepetopsina McLean, 1990
      • Superfamily Lepetopsoidea McLean, 1990

Subclass Orthogastropoda Ponder & Lindberg, 1996 (earlier Prosobranchia, Opisthobranchia)
Incertæ sedis

  • Order Murchisoniina Cox & Knight, 1960 (fossil)
      • Superfamily Murchisonioidea Koken, 1889
      • Superfamily Loxonematoidea Koken, 1889
      • Superfamily Lophospiroidea Wenz, 1938
      • Superfamily Straparollinoidea
    • Grade Subulitoidea Lindström, 1884

Superorder Cocculiniformia Haszprunar, 1987

      • Superfamily Cocculinoidea Dall, 1882
      • Superfamily Lepetelloidea Dall, 1882 (deep sea limpets)

Superorder 'Hot Vent Taxa' Ponder & Lindberg, 1997

  • Order Neomphaloida Sitnikova & Starobogatov, 1983
      • Superfamily Neomphaloidea McLean, 1981 (hydrothermal vents limpets)
      • Superfamily Peltospiroidea McLean, 1989

Superorder Vetigastropoda Salvini-Plawen, 1989 (limpets)

      • Superfamily Fissurelloidea Fleming, 1822 (keyhole limpets)
      • Superfamily Haliotoidea Rafinesque, 1815 (abalones)
      • Superfamily Lepetodriloidea McLean, 1988 (hydrothermal vent limpets)
      • Superfamily Pleurotomarioidea Swainson, 1840 (slit shells)
      • Superfamily Seguenzioidea Verrill, 1884
      • Superfamily Trochoidea Rafinesque, 1815 (top shells)

Superorder Neritaemorphi Koken, 1896

  • Order Cyrtoneritomorpha (fossil)
  • Order Neritopsina Cox & Knight, 1960
      • Superfamily Neritoidea Lamarck, 1809

Superorder Caenogastropoda Cox, 1960

  • Order Architaenioglossa Haller, 1890
      • Superfamily Ampullarioidea J.E. Gray, 1824
      • Superfamily Cyclophoroidea J.E. Gray, 1847 (terrestrials)
  • Order Sorbeoconcha Ponder & Lindberg, 1997
    • Suborder Discopoda P. Fischer, 1884
      • Superfamily Campaniloidea Douvillé, 1904
      • Superfamily Cerithioidea Férussac, 1822
    • Suborder Hypsogastropoda Ponder & Lindberg, 1997
    • Infraorder Littorinimorpha Golikov & Starobogatov, 1975
      • Superfamily Calyptraeoidea Lamarck, 1809
      • Superfamily Capuloidea J. Fleming, 1822
      • Superfamily Carinarioidea Blainville, 1818 (formerly called Heteropoda)
      • Superfamily Cingulopsoidea Fretter & Patil, 1958
      • Superfamily Cypraeoidea Rafinesque, 1815 (cowries)
      • Superfamily Ficoidea Meek, 1864
      • Superfamily Laubierinoidea Warén & Bouchet, 1990
      • Superfamily Littorinoidea (Children), 1834 (periwinkles)
      • Superfamily Naticoidea Forbes, 1838 (moon shells)
      • Superfamily Rissooidea J.E. Gray, 1847 (Risso shells) (includes genus oncomelania, schistosomiasis transmission vector)
      • Superfamily Stromboidea Rafinesque, 1815 (true conchs)
      • Superfamily Tonnoidea Suter, 1913
      • Superfamily Trivioidea Troschel, 1863
      • Superfamily Vanikoroidea J.E. Gray, 1840
      • Superfamily Velutinoidea J.E. Gray, 1840
      • Superfamily Vermetoidea Rafinesque, 1815 (worm shells)
      • Superfamily Xenophoroidea Troschel, 1852 (carrier shells)
    • Infraorder Ptenoglossa J.E. Gray, 1853
      • Superfamily Eulimoidea Philippi, 1853
      • Superfamily Janthinoidea Lamarck, 1812
      • Superfamily Triphoroidea J.E. Gray, 1847
    • Infraorder Neogastropoda Thiele, 1929
      • Superfamily Buccinoidea (whelks, false tritions)
      • Superfamily Cancellarioidea Forbes & Hanley, 1851
      • Superfamily Conoidea Rafinesque, 1815
      • Superfamily Muricoidea Rafinesque, 1815

Superorder Heterobranchia J.E. Gray, 1840

  • Order Heterostropha P. Fischer, 1885
      • Superfamily Architectonicoidea J.E. Gray, 1840
      • Superfamily Nerineoidea Zittel, 1873 (fossil)
      • Superfamily Omalogyroidea G.O. Sars, 1878
      • Superfamily Pyramidelloidea J.E. Gray, 1840
      • Superfamily Rissoelloidea J.E. Gray, 1850
      • Superfamily Valvatoidea J.E. Gray, 1840
  • Order Opisthobranchia Milne-Edwards, 1848
    • Suborder Cephalaspidea P. Fischer, 1883
      • Superfamily Acteonoidea D'Orbigny, 1835
      • Superfamily Bulloidea Lamarck, 1801
      • Superfamily Cylindrobulloidea Thiele, 1931
      • Superfamily Diaphanoidea Odhner, 1914
      • Superfamily Haminoeoidea Pilsbry, 1895
      • Superfamily Philinoidea J.E. Gray, 1850
      • Superfamily Ringiculoidea Philippi, 1853
    • Suborder Sacoglossa Von Ihering, 1876
      • Superfamily Oxynooidea H. & A. Adams, 1854
    • Suborder Anaspidea P. Fischer, 1883 (sea hares)
      • Superfamily Akeroidea Pilsbry, 1893
      • Superfamily Aplysioidea Lamarck, 1809
    • Suborder Notaspidea P. Fischer, 1883
      • Superfamily Tylodinoidea J.E. Gray, 1847
      • Superfamily Pleurobranchoidea Férussac, 1822
    • Suborder Thecosomata Blainville, 1824 (sea butterflies)
      • Infraorder Euthecosomata
        • Superfamily Limacinoidea
        • Superfamily Cavolinioidea
      • Infraorder Pseudothecosomata
        • Superfamily Peraclidoidea
        • Superfamily Cymbulioidea
    • Suborder Gymnosomata Blainville, 1824 (sea angels)
      • Family Clionidae Rafinesque, 1815
      • Family Cliopsidae Costa, 1873
      • Family Hydromylidae Pruvot-Fol, 1942
      • Family Laginiopsidae Pruvot-Fol, 1922
      • Family Notobranchaeidae Pelseneer, 1886
      • Family Pneumodermatidae Latreille, 1825
      • Family Thliptodontidae Kwietniewski, 1910
Clausiliidae or Door Snails
    • Suborder Nudibranchia Blainville, 1814 (nudibranchs)
    • Infraorder Anthobranchia Férussac, 1819
      • Superfamily Doridoidea Rafinesque, 1815
      • Superfamily Doridoxoidea Bergh, 1900
      • Superfamily Onchidoridoidea Alder & Hancock, 1845
      • Superfamily Polyceroidea Alder & Hancock, 1845
    • Infraorder Cladobranchia Willan & Morton, 1984
      • Superfamily Dendronotoidea Allman, 1845
      • Superfamily Arminoidea Rafinesque, 1814
      • Superfamily Metarminoidea Odhner in Franc, 1968
      • Superfamily Aeolidioidea J.E. Gray, 1827
  • Order Pulmonata Cuvier in Blainville, 1814 (pulmonates)
    • Suborder Systellommatophora Pilsbry, 1948
      • Superfamily Onchidioidea Rafinesque, 1815
      • Superfamily Otinoidea H. & A. Adams, 1855
      • Superfamily Rathouisioidea Sarasin, 1889
    • Suborder Basommatophora Keferstein in Bronn, 1864 (freshwater pulmonates, pond snails)
      • Superfamily Acroloxoidea Thiele, 1931
      • Superfamily Amphiboloidea J.E. Gray, 1840
      • Superfamily Chilinoidea H. & A. Adams, 1855
      • Superfamily Glacidorboidea Ponder, 1986
      • Superfamily Lymnaeoidea Rafinesque, 1815
      • Superfamily Planorboidea Rafinesque, 1815
      • Superfamily Siphonarioidea J.E. Gray, 1840
    • Suborder Eupulmonata Haszprunar & Huber, 1990
    • Infraorder Acteophila Dall, 1885 (= formerly Archaeopulmonata)
      • Superfamily Melampoidea Stimpson, 1851
    • Infraorder Trimusculiformes Minichev & Starobogatov, 1975
      • Superfamily Trimusculoidea Zilch, 1959
    • Infraorder Stylommatophora A. Schmidt, 1856 (land snails)
    • Subinfraorder Orthurethra
      • Superfamily Achatinelloidea Gulick, 1873
      • Superfamily Cochlicopoidea Pilsbry, 1900
      • Superfamily Partuloidea Pilsbry, 1900
      • Superfamily Pupilloidea Turton, 1831
    • Subinfraorder Sigmurethra
      • Superfamily Acavoidea Pilsbry, 1895
      • Superfamily Achatinoidea Swainson, 1840
      • Superfamily Aillyoidea Baker, 1960
      • Superfamily Arionoidea J.E. Gray in Turnton, 1840
      • Superfamily Buliminoidea Clessin, 1879
      • Superfamily Camaenoidea Pilsbry, 1895
      • Superfamily Clausilioidea Mörch, 1864
      • Superfamily Dyakioidea Gude & Woodward, 1921
      • Superfamily Gastrodontoidea Tryon, 1866
      • Superfamily Helicoidea Rafinesque, 1815
      • Superfamily Helixarionoidea Bourguignat, 1877
      • Superfamily Limacoidea Rafinesque, 1815
      • Superfamily Oleacinoidea H. & A. Adams, 1855
      • Superfamily Orthalicoidea Albers-Martens, 1860
      • Superfamily Plectopylidoidea Moellendorf, 1900
      • Superfamily Polygyroidea Pilsbry, 1894
      • Superfamily Punctoidea Morse, 1864
      • Superfamily Rhytidoidea Pilsbry, 1893
      • Superfamily Sagdidoidera Pilsbry, 1895
      • Superfamily Staffordioidea Thiele, 1931
      • Superfamily Streptaxoidea J.E. Gray, 1806
      • Superfamily Strophocheiloidea Thiele, 1926
      • Superfamily Trigonochlamydoidea Hese, 1882
      • Superfamily Zonitoidea Mörch, 1864
      • ? Superfamily Athoracophoroidea P. Fischer, 1883 (= Tracheopulmonata)
      • ? Superfamily Succineoidea Beck, 1837 (= Heterurethra)

Other extant classes of the Mollusca are Bivalvia, Scaphopoda, Aplacophora, Polyplacophora, Monoplacophora, and Cephalopoda.

References

  • Breen, P. A. 1971. “Homing behavior and population regulation in the limpet Acmaea (Collisella) digitalis.” Veliger 14: 177-183.
  • Götting, K.-J. 1994. “Schnecken.” In U. Becker, S. Ganter, C. Just, and R. Sauermost, Lexikon der Biologie. Heidelberg: Spektrum Akademischer Verlag. ISBN 3860251562.
  • Jeffery, P. 2001. Suprageneric classification of class Gastropoda. London: The Natural History Museum.
  • Ponder, W. F., and D. R. Lindberg. 1997. “Towards a phylogeny of gastropod molluscs: An analysis using morphological characters.” Zoological Journal of the Linnean Society 119: 83-2651.
  • Towle, A. 1989. Modern Biology. Austin, TX: Holt, Rinehart, and Winston. ISBN 0030139198.

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