BIOL 321 Lecture Notes - Lecture 15: Cephalization, Mesothelium, External Fertilization
15 Oct 2016
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Document Summary
Phylogeny & taxonomy: includes things from bivalves to cephalopods, two major subdivisions of the mollusca: the subphylum conchifera (gastropoda, bivalvia, scaphopoda, cephalopoda),(more familiar, we like to eat them) and the subphylum aculifera (polyplacoferans, neomeniomorpha, and shaetodermomorpha) Visceropallium- includes mantle and visceral organs within the body. Cephalopodium- head is consolidated with the foot on the ventral side. (term literally means head-foot) Dorso surface more made for protection against abrasion of environment or predators. Ventral surface specialized for locomotion: calcium carbonate shell. They have shell valves (or shell pieces) are calcium carbonate, the dorsal shell plates are secreted by a tissue around the rim called the mantle: mantle cavity, gills, osphradia. The mantle tissue is a ring of tissues around the periphery. Mantle cavity takes different forms in different types of molluscs but always houses the gills of a mollusk. Gills are situated inside the mantle cavity and are ciliated and maintain circulation of water through the mantle cavity.
