Origin of Animals First Complex Animals the Burgess Shale Fossil

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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

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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 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

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Fig. 32-UN1 Common ancestor of all animals

Tissue Compatibility Metazoa Sponges (basal animals)

Ctenophora Eumetazoa

Cnidaria Bilateria animals) (most 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