Preface to Class of Monoplacophora
Literal meaning: Bearing one plate
Common name: None
Members of this class have a single, cap-shaped shell similar
to a limpet.
The animal body is composed of a head, a mantle
and a large flattened foot. |
The apex of the shell is forward on the Monoplacophorans.
The shell is relatively small ranging in size from 3 to 30 mm in diameter.
pedal retractor muscles and nerve connections are found in a
pallial groove which surrounds the foot.
These organs repeat serially. They consist of six pairs of nephrida,
five or six pairs of gills, and eight pairs of dorso-ventral pedal retractor muscles.
There are two pairs of gonads. No eyes or tentacles are present.
Habitat: All species are marine. Their range is limited to deep waters mostly in ocean trenches.
Etc.: Monoplacophorans were thought to be extinct until 1952 when ten
living specimens were dredged off the coasts of Costa Rica and Peru by the
Galathea Expedition. At present, only a few living species are known to exist.
Reference: Class - Monoplacophora
Ref. Keen, 1971 p 857
Vaught, 1989 p viii,5