Comparative buccal anatomy in Helisoma (mollusca, pulmonata, basommatophora)

Abstract

Dissections were performed to document buccal anatomy in three species of the pulmonate genus Helisoma Swainson, 1840. The 28 muscles which are responsible for radular feeding in these animals are organized in three concentric and integrated envelopes. The deepest of these includes muscles which manipulate the radula about the odontophoral cartilage. Elements of the middle envelope direct movements of the cartilage within the buccal cavity, and muscles of the outer envelope control movements of the buccal mass within the cephalic haemocoel. Motion analysis by videomicrography showed that muscles of the middle and outer envelopes contribute to the action of radular feeding by acting as antagonists to other muscles and to hydrostatic elements of the buccal apparatus. Observations of radular dentition showed that although each of the three species examined has a unique radula, especially with regard to the specific details of tooth shape, all resemble a radula characteristic of the Planorbidae with regard to other, more general, aspects of ribbon architecture.

From the knitting shop: the first physical and dynamic model of the taenioglossan radula (Mollusca: Gastropoda) aids in unravelling functional principles of the radular morphology

“…Each gastropod was placed on its ventral side and carefully a transversal cut through the snout, followed by a longitudinal cut in posterior direction, was executed to expose the buccal mass. One large complex of buccal mass muscles surrounds the odontophoral cartilages (for morphological descriptions, see [1,[64][65][66][67][68][69][70][71][72][73][74][75][76][77]); the radula, with attached alary processus to both sides, is also connected to both buccal mass muscles. Thus, all these structures together can be picked by tweezers and loosened from the surrounding tissues, connecting it with the body wall.…”

Development of foregut and proboscis in the buccinid neogastropod Nassarius mendicus: Evolutionary opportunity exploited by a developmental module

“…The radula is the core component of the buccal mass or odontophore, which also includes a complex cassette of muscles, innervating neurons, and often a set of cartilage-like elements (Fretter and Graham, 1962;Graham, 1973;Bulloch and Dorsett, 1979;Smith, 1990). The earliest gastropods probably used the radula as a rasping structure to scrape algal films from solid substrates, a feeding method retained by many extant gastropods (Ponder and Lindberg, 1997).…”

Radular mechanosensory neuron in the buccal ganglia of the terrestrial slug, Incilaria fruhstorferi

“…The muscles were named according to those of Lymnaeacea (Demian 1962) or Helisoma (Smith 1990), because the basic configuration of their buccal muscles is similar to that of Incilaria. Fig.…”