Sensory Organs in the Hairy Girdles of Some Mopaliid Chitons

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Esther M. Leise, Professor (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:

Abstract: The polyplacophoran mantle secretes the shell plates, houses the gills in the pallial grooves, and forms a muscular perinotum or girdle that encircles the shell and viscera. The epidermis of this girdle occurs as papillae of columnar cells dispersed over an otherwise cuboidal epithelium. Depending upon the species, these papillae can produce a variety of hard structures: calcareous scales, spicules, or spines and/or chitinous hairs. Some papillae also produce bulbous outgrowths called nodules or "morgensternförmigen Körper" (morning star-shaped bodies). These nodules contain the dendrites of sensory neurons and are thought to be mechanoreceptive. Nodules can occur alone in the cuticle or in conjunction with calcareous spicules. Nodules of this type are present in the hairs of chitons in the genus Mopalia. Hairs from other mopaliid genera are also innervated, although they can lack these particular structures. In most species of chitons that I examined, nodules are made in conjunction with the ventral girdle spicules and the marginal spicules. These presumptive mechanoreceptors could be ubiquitous among chitons, as all species possess marginal spicules and overlapping ventral spicules. Hairs could have evolved to extend the reach of these tactile receptors beyond the surface of the animal's body, as well as to provide mechanical protection from desiccation and predation.

Additional Information

American Malacological Bulletin 6(1):141-151
Language: English
Date: 1988
Polyplacophoran mantle, pallial grooves, perinotum, papillae, columnar cells, cuboidal epithelium, dendrites, sensory neurons

Email this document to