Cambrian & Ordovician - Key Words

Cambrian & Ordovician - Key Words - CAMBRIAN &...

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C AMBRIAN RDIVICIAN E ON K EY W ORDS - Acoelomate - Multicellular organism, triloblasts - SOLID core of mesodermal tissue - NO hollow areas OUTSIDE organs - E.g. – flatworm - Algal mats - In benthic zone - LAYER of algae / cyanobacteria on ocean bottom - NEW undiscovered habitat for Cambrian burrowers - E.g. – organisms now had feeding, protection + anchorage - Archaeocyte (Amoebocyte) - In sponges - Amoeboid stem cells - Sperm + egg = larval baby sponge - Assymetric Body Plan - NO axis of symmetry (oral to aboral axis) - E.g. - Sponges - Benthic Zone - Ecological region at LOWEST level of a body of water - INCLUDES sediment surface + sub-surface layers - In Cambrian Era ο Undiscovered NEW habitat ο Allowed for burrowers to have (feeding, anchorage, protection) - Bilateral Symmetry Body Plan - Only ONE axis of symmetry (oral to aboral axis) - VAST bilaterally symmetric, BETTER for orientation - E.g. – lobster (dorsal-ventricle symmetry), human (oral-aboral symmetry) - Bivalve (Type of Mollusc) - Composed of 2 shells - Symmetry: bilateral - Feeding: filter feeds - Live: sediments in seas OR freshwater - E.g. – clams, mussels, scallops, oysters - Blastopore (In Embryo during Gastrulation) - Site of gastrulation initiation in area ASSIGNED to be endoderm - Opening of the archenterons @ ventral region of embryo - In protostome: becomes mouth - In deuterostome: becomes anus - Blastula (8 days AFTER fertilization)
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- cleavage stage embryo - liquid-filled sphere (blastocoel = fluid-filled cavity) - wall = single layer of cells - implantation ONTO uterine wall occurs - E.g. - echinoderm / amphibian embryos - Bryozoa (Lophophorates) - Animalia - Tiny SESSILE colonies, build up skeletons of calcium carbonate - Similar to ο pollups in cnideria ο coral - Feed, How? ο Extend arms upwards into ocean ο Mouth open ο Food particles FALL onto ciliated tentacles ο Move food to mouth - Burgess Shale Fossils (Yoho National Park, BC) - 505 ma (Middle Cambrian) - Why So Special? ο Anaerobic area ο Ornate invertebrates ο Experiments of multicellular life ο ANCIENT diversity in multicellular organisms - Soft-body organisms LAYERED in sediments (shale) - Bodies don’t decay = PERFECTLY preserved fossils - Cambrian Period - (543 – 490 ma … 1 st period in Phanerozoic Era) - EXPLOSION (BOOOOOMMMM!!!) of ο Multi-cellular organisms in fossils ο Invertebrates ο Diversity ο Experimentation in species - Continents flooded by shallow sees - Hard-shelled animals make appearance - Cambrian Burrowers - In benthic zone - Discovered NEW untapped habitat in Ediacaran, continued to use - Algal mat FULL of nutrients / food to LIVE on - Advantages ο Feeding – new food source at BOTTOM of ocean ο Anchorage – habitat / home NOT washed away ο Protection – escape / return EASILY - Cambrian Explosion - (around 530 ma) - Rapid appearance of major group of complex animals - Evidenced by fossil record
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- “experimentation” / diversity in multi-cellular life - (volcanic vents) → (melt ice) → (vent gas) → (↑GG) → (Earth = warm) → (ice
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Cambrian & Ordovician - Key Words - CAMBRIAN &...

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