Monoplacophora - Definition and Overview

Monoplacophora is a class of Mollusks thought to be extinct until 1952, when a living animal was dredged up from deep marine sediments. So far, twelve living species have been discovered. The name 'Monoplacophora' means 'bearing one plate'. They live deep down in ocean trenches.

Little is known about the Monoplacophora. They have a single, flat, rounded bilateral shell and resemble chitons (Class Polyplacophora) or more precisely, limpets (Class Gastropoda). Their shell is often thin and fragile. The apex of the shell is forward.

Their body segments exhibit a primitive serial repetition with similar organs in several segments. This form resembles the anatomy of worms of Phylum Annelida, suggesting a link between mollusks and annelids.

They move on a rounded foot. Respiration is through five or six pairs of gills on either side of the body.

Their reduced head lacks eyes or tentacles. They seem to feed on mud or bottom detritus.

Neopilina galatheae was the first known living specimen. Previous specimens dated from the Paleozoic. These mollusks are about 0.5 to 3.0 cm in length.

Taxonomy

Order Tryblidiida Tryblidioidea

Order Tryblidioidea

• Superfamily Tryblidiacea
  • Family Laevipilinidae
    • Genus Laevipilina. H. McLean, 1979
  • Family Monoplacophoridae
    • Genus Monoplacophorus L. I. Moskaslev, Y. A. Starobogatov & Z. A. Filatova, 1983
  • Family Neopilinidae
    • Genus Neopilina H. Lemche, 1957
      • Subgenus Lemchephila L. I. Moskalev, Y. A. Starobogatov & Z. A. Filetove, 1983
      • Subgenus Lemchephyala (= Lemchephila) L. I. Moskalev, Y. A. Starobogatov & Z. A. Filetove, 1983
    • Genus Micropilina
    • Genus Rokopella
    • Genus Veleropilina
  • Family Tryblidiidae
    • Subfamiliy Neopilininae
      • Genus Neopilina H. Lemche, 1957
        • Subgenus Neopilina
          • Species Neopilina (Neopilina) galathea H. Lemche, 1957
          • Species Neopilina (Neopilina) veleronis R. J. Menzies & W. Layton, 1963
    • Subfamily Tryblidiinae
  • Family Vemidae
    • • Genus Vema. H. Clarke & R. J. Menzies, 1959
        • Species Vema ewingi. H. Clarke & R. J. Menzies, 1959

External links

• Conchology, Inc. (http://www.conchology.be/)
• Anatomy (http://www.biology.ucsc.edu/classes/bio136/molluscs/monoplacophora/monoplacophora.html)