Thesis (Ph.D.)--Murdoch University, 2007. / Thesis submitted to the Division of Science and Engineering. Includes bibliographical references (leaves 192-195).

Sacoglossa belongs to the Subclass of Opithsobrabchia (Class: Gastropoda). There are about 300 species in the world. The radula of Sacoglossa is composed of ascending limb, descending limb, and a ascus sac to store used teeth. This ascus sac is a unique character of sacoglossans in mollusus. In this study, I compared the morphology, and the composition of elements in sacoglossan radulae. A total of 16 species in 5 families, including 12 new records, has been observed. Their teeth morphology was triangular or blade-like. The radula sac is surrounded by a layer of epithelium cells and the arrangement of the teeth in the sac was linear, dense or fraction. Positive correlations between body length and the number of ascending radular teeth, descending radular teeth, teeth in ascus sac or the total number of teeth were found except for Volvatella vigourouxi (Family: Volvatellidae). The elemental compositions in various radula parts were examined by energy dispersive spectrometer. I found that sacoglossan teeth were composited by Fe, Na, Mg, Si, P, S and Ca, and no significant difference among parts but significantly different among species. In contrast, elemental compositions of sacoglossans were significantly different from Tambja sp. (Order: Nudibranchia), Aplysia parvula (Order: Anaspidea) and Cellana toreuma (Order: Archaeogastropoda). In the meantime, sacoglossans and Tambja sp. were closer than others. Additionally, hollow or broken teeth were found in some sacogloosan ascus indicates that tooth reabsorption may present. However, further study is necessary to elucidate the reabsorption mechanism.

Thesis (M.Sc.) -- Memorial University of Newfoundland. / Typescript. Bibliography : leaves 232-238. Also available online.

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