BIOL 2P92 Study Guide - Final Guide: Symmetry In Biology, Sponge, The Sponge

• School: Brock University
• Department: Biological Sciences
• Course: BIOL 2P92
• Professor: Miriam Richards

Document Summary

Lab 1: porifera and cnidaria: sponges referred to as parazoans (not metazoans) because they are missing, do not have a true issue layer, choanocytes are lagellated cells that have a collar like ring of microvilli surrounding a lagellum. Asymmetry: no deinite shape and cannot be divided into 2 idenical halves. Radial symmetry: arrangement around central oral-aboral (longitudinal) body axis; plane divides animal into mirror images. Modiied by the arrangement of some structures in pair, or other combinaions, around central axis. Biradial: essenially radial, but only 2 planes through the longitudinal axis create truly similar halves. Pentaradial: symmetry in 5 planes, body symmetry involving 5 or more parts arranged concentrically around a central axis made up of an oral/aboral pole. Bilateral symmetry: body divided into 2 idenical halves by only one speciic plane passing through longitudinal axis. Appearance of bilateral symmetry is a major innovaion in animal evoluion. Earliest sponges 600 million years (oldest known animals)