2/14/13 Figure 26.21 Origin of Animals Eukarya Land plants Dinoflagellates Green algae Forams Ciliates Diatoms Red algae • Finish Flowering Plants Amoebas Cellular slime molds • Phylogenetic History Euglena Trypanosomes • Animal body plans Animals Leishmania – Tissue systems Fungi • Diversification in the pre- Sulfolobus Green Cambrian nonsulfur bacteria Thermophiles (Mitochondrion) Spirochetes Halophiles Chlamydia COMMON ANCESTOR Green OF ALL sulfur bacteria LIFE Methanobacterium Bacteria Cyanobacteria Archaea (Plastids, including chloroplasts) Feb 15, 2013 Figure 25.T01-1 First complex animals 650 mya • Soft-bodied; radial & bilateral symmetry The fossil record – the Cambrian Explosion The Burgess Shale fossil bed (542-525 million years ago) Hallucinigenia 1 2/14/13 Burgess Shale! Is this your ancestor? Diversity! • Colonial Choanoflagellates are the sister group to all other animals Not fully multicellular organisms Simple Animal Phylogeny Sponges Individual choanoflagellate Choanoflagellates OTHER EUKARYOTES Sponges Animals Collar cell (choanocyte) Other animals Anatomy of a sponge It’s what’s between cells that defines multicellularity in animals. Fig 33.4 Integrin 2 2/14/13 Fig. 32-UN1 Common ancestor of all animals Tissue Compatibility Metazoa Sponges (basal animals) Ctenophora Eumetazoa Cnidaria Bilateria (most animals) True Acoela (basal tissues bilaterians) Deuterostomia Bilateral summetry Lophotrochozoa Three germ layers Ecdysozoa http://www.scielo.br/scielo.php?pid=S1982-56762008000500007&script=sci_arttext Fig. 32-7 Fig. 32-9 Protostome development Deuterostome development (a) Cleavage Eight-cell stage Eight-cell stage Spiral and determinate Radial and indeterminate Key (b) Coelom formation Coelom (a) Radial symmetry Ectoderm Mesoderm Archenteron Endoderm Coelom Mesoderm Blastopore Blastopore Mesoderm Solid masses of mesoderm Folds of archenteron split and form coelom. form coelom. (c) Fate of the blastopore Anus Mouth Digestive tube Mouth Anus (b) Bilateral symmetry Mouth develops from blastopore. Anus develops from blastopore. Figure 25.10 Coelom Most animals have Body covering (from ectoderm) Sponges a central body Tissue layer lining coelom Cnidarians Digestive tract and suspending cavity (from endoderm) internal organs (from mesoderm) Echinoderms (Coelom) (a) Coelomate Chordates Body covering (from ectoderm) Brachiopods Pseudocoelom Muscle layer (from mesoderm) Annelids Digestive tract (from endoderm) (b) Pseudocoelomate Molluscs Body covering (from ectoderm) Tissue- Arthropods filled region (from mesoderm) PROTEROZOIC PALEOZOIC Ediacaran Cambrian Wall of digestive cavity (from endoderm) 635 605 575 545 515 485 0 (c) Acoelomate Time (millions of years ago) 3 .