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| Mollusc larvae A chiton's trochophore, a snail's veliger, and a freshwater clam's glochidium |
We talked about the general mode of reproduction in molluscs and discussed the larval stages that characterize the phylum: trochophora, veliger, and, in some cases (Unioniodea), glochidium.
We even mentioned one of the masterpieces of scientific poetry: The Ballad of the Veliger, by Walter Garstang (worth the read, for mollusc larval development and for understanding torsion in gastropods)
We then discussed the result of adaptive radiation in molluscs, which gave rise to the diversity we observe today, from an ancestral mollusc. We talked a little about mollusc phylogeny too.
After discussing such intraphylum diversity we started talking about the first classes: Monoplacophora and Polyplacophora (chitons). For both groups we discussed how their characteristics differ from those covered when discussing the generalized mollusc. We payed special attention to the shell, the foot, the mantle cavity and the visceral mass.
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| Monoplacophorans and a polyplacophoran |
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