BIO 1130 Lecture Notes - Burgess Shale, Cambrian Explosion, Symmetry In Biology

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

Document Summary

Layer of algae / cyanobacteria on ocean bottom. Organisms now had feeding, protection + anchorage. No axis of symmetry (oral to aboral axis) Ecological region at lowest level of a body of water. Allowed for burrowers to have (feeding, anchorage, protection) Only one axis of symmetry (oral to aboral axis) Site of gastrulation initiation in area assigned to be endoderm. Opening of the archenterons @ ventral region of embryo. Blastula (8 days after fertilization) o o cleavage stage embryo liquid-filled sphere (blastocoel = fluid-filled cavity) wall = single layer of cells implantation onto uterine wall occurs. Tiny sessile colonies, build up skeletons of calcium carbonate. Extend arms upwards into ocean: mouth open. Food particles fall onto ciliated tentacles: move food to mouth. Cambrian period (543 490 ma 1st period in phanerozoic era) Explosion (booooommmm!!!) of: multi-cellular organisms in fossils. Discovered new untapped habitat in ediacaran, continued to use. Algal mat full of nutrients / food to live on.