Article
Article
Aplacophora
Article By:
Scheltema, Amélie H. Woods Hole Oceanographic Institution, Woods Hole, Massachusetts.
Last reviewed:October 2019
DOI:https://doi.org/10.1036/1097-8542.043300
Any of the vermiform (wormlike) marine mollusks covered by a cuticle invested with innumerable calcareous scales or spines (sclerites) forming a scleritome. There are two groups that together are known as the Aplacophora: (1) Chaetodermomorpha or Caudofoveata and (2) Neomeniomorpha or Solenogastres. Aplacophorans are a small, primarily deep-sea group, with approximately 400 named species and with more still to be described. Most species are less than 10 mm (0.4 in.) in length, but a few attain 300 mm (12 in.). The head, with a mouth, is poorly differentiated; there is a small posterior mantle cavity, or cloaca. Despite their specialized shape (Figs. 1 and 2), aplacophorans retain a primitive molluscan condition in the radula (rasping structure), integument, gonad-pericardium, muscles, and nervous system. See also: Chaetodermomorpha; Mollusca; Neomeniomorpha
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