BI256 Lecture Notes - Lecture 1: Ctenophora, Jellyfish, Cambrian Explosion
Document Summary
Animal architecture chapter 9 lecture 1 bi256. Cnidarian polyps have radial symmetry and cell tissue grade of organization. Know due to fossil record based on body plan. There were few groups of animals during this time (about 100 phyla of animals emerging) Started with little diversity, very warm sea, and abundant oxygen = explosion of diversity and very fast evolution. 34 phyla of extant living multicellular animals with a distinctive body plan today. Ancestors of phyla limited structure of descendants. Regular arrangement of body structures relative to the axis of the body. Animals can be bisected along at least one plan. How body plans differ? in grades of organization. No body axis and no plane symmetry. Body has the general form of a cylinder (tubular, vase or bowl shape found in some sponges, polyps, hydra: floating animals (poor swimmers ex jelly fish, sessile animals (sea anemone senses upwards)