BI236 Lecture Notes - Lecture 3: Symmetry In Biology, Cambrian Explosion, Sagittal Plane
Document Summary
Cnidarian polyps have radial symmetry and cell-tissue grade of organization. New designs for living: cambrian explosion (500 mya, 34 major phyla of living multicellular animals with a distinctive body plan, body plan: Regular arrangement of body structures relative to axis of the body. Animals can be bisected along at least one plan. Body plans: animal symmetry: asymmetry, no bod axis and no plane of symmetry. Animals can be divided along a sagittal plane into 2 identical portions (left and right: associated with cephalization, major innovation, controlled mobility, surfaces differentiate as dorsal (protection) and ventral (locomotion) A variety of descriptive terms are used to describe orientation in bilateral animals (a) protozoa. Protozoa(cid:374) (cid:862)(cid:272)ell(cid:863) complete organism that conducts all basic functions of life (i. e. lives independently) (b-e) metazoa. Metazoan cell a single unit that is part of the whole organism. Hierarchical organization of animal complexity (a (b (c (d (e. It is an analog for an ancestral metazoan.
