BIO 3334 Lecture Notes - Lecture 6: Opisthosoma, Chemosynthesis, Trochophore
12 Apr 2017
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Free swimming larval stage looks like spinning top. Band of cilia surrounding equatorial portion of larva above mouth - prototroch. Some have second ring of cilia metatroch around middle of larva. Digestive tract is ciliated mouth leads to stomach ends at anus. Mesoderm forms from cells near blastopore proliferates between endoderm and forms during gastrulation and outer ectoderm. Schizocoel true body cavity forms by schizocoelous splitting of mesoderm symplesimorphie of mollusa, spinuncula and annelida. True coelom exist in annelids and molluscs from schizocoely. True coelom example of secondary body cavity coelom is lined with epithelium. Blood vessels form two layers of coelomic epithelia come together with space between layers lumen of blood vessels form closed blood vessels including pumping hearts - coelom is pericardial cavity. Filter coelomic fluid unlike protonephridia, produce an ultrafiltrate - take up unmodified coelomic fluids. Both open to outside of animal through nephridipore.
