BSC 2011 Lecture Notes - Lecture 13: Blubber, Integumentary System, Torpor
Document Summary
General characteristics (not synapomorphies: multicellular, heterotrophs, internal digestion, motile. Synapomorphies: gap junctions (unique to animals, common extracellular molecules (proteoglycans and collagen, hox genes (similar developmental genes) Key evolutionary divergence events: sponges v. non-sponges (eumetazoans) distinct organ systems. Cells not arranged in any particular way eumetazoans have specialized cells: diploblastic v. triploblastic organisms symmetry. Diploblastic = endoderm and ectoderm placozoa, ctenophore, and cnidarian: ctenophores and cnidarians have radial symmetry (more compelx) Triploblastic = endoderm, mesoderm, ectoderm: have bilateral symmetry, all triploblastic organisms have bilateral symmetry, protostomes v. deuterostomes - Protostomes mouth before anus (mollusks and arthropods) Deuterostomes anus before mouth (echinoderms and chordates) Body plan = general arrangement of body parts and organ systems in an animal. Symmetry: asymmetrical (earliest sponges, radial (jellyfish and starfish independent evolution, bilateral. Associated with cephalization (sensory organs concentrated at anterior of body) Body cavity structure: triploblastic = tube within a tube. All must take in o2 and nutrients.