BISC 102 Study Guide - Final Guide: Cambrian Explosion, Burgess Shale, Wiwaxia
19 Jan 2018
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Lec 7: history of life - animals: characteristics: multicellular eukaryotes. Chemoheterotrophs (obtain energy + carbon by eating organic materials) that ingests their food. Monophyletic: cambrian [~541 mya] fauna marked appearance of modern animal phyla. Excellent representation of soft-bodied organisms (external and internal) Some reassigned to modern phyla: cambrian fauna: some are early chordates, incl. Notochord, dorsal nerve chord, pharyngeal pouches (feeding structures) Diversity of complex animal features: eyes, gills, carapaces (hard exoskeletons), sensory + jointed appendages. Increased oxygen: aerobic respiration more efficient than anaerobic (more atp per glucos) Increased metabolic efficiency, meaning animals can grow larger, be more active (fueled muscles) Predation: fauna provided first evidence of body plans that allowed motility, defensive structures, appendages for sensing prey. New niches: evidence of animals under, on, above sea floor. Evolved in response to abiotic environment + other organisms. New genes + body plans: evolution of hox genes that play regulatory role in development.
