BIO 1130 Lecture : bio key terms part 3.docx

• School: University of Ottawa
• Department: Biology
• Course: BIO 1130
• Professor: Jon Houseman

Document Summary

Cambrian and ordivician: acoelomate, triploblastic animals (phylum platyhelminthes) that do not have an internal body cavity that separates the gut from the muscles of the body. Instead they have a mass of cells derived largely from mesoderm that packs the region between the gut and the body wall. Although this term could be applied to other lower phyla, it is most accurately used with the triploblasts rather than diploblasts. There was an explosion of these soft bodied burrowers which is independent of mineral based fossilization. This would suggest that the explosion may have been real. Amebocyte, the large, macrophage-like amoeboid cells in the mesohyl that are totipotent and can differentiate into any other type of sponge cell; are also phagocytic and play a role in digestion and internal transport. Archenteron, the name given to the primitive gut, the first tube that runs through the developing embryo and is open to the external environment.