Fig 32 1 Fig 32 2 3 Blastocoel

Fig. 32 -1

Fig. 32 -2 -3 Blastocoel Cleavage Endoderm Cleavage Blastula Ectoderm Zygote Eight-cell stage Gastrulation Blastocoel Cross section of blastula Gastrula Blastopore Archenteron

Fig. 32 -3 Individual choanoflagellate Choanoflagellates OTHER EUKARYOTES Sponges Animals Collar cell (choanocyte) Other animals

Fig. 32 -7 (a) Radial symmetry (b) Bilateral symmetry

Fig. 32 -8 Coelom Digestive tract (from endoderm) Body covering (from ectoderm) Tissue layer lining coelom and suspending internal organs (from mesoderm) (a) Coelomate Body covering (from ectoderm) Pseudocoelom Muscle layer (from mesoderm) Digestive tract (from endoderm) (b) Pseudocoelomate Body covering (from ectoderm) Tissuefilled region (from mesoderm) Wall of digestive cavity (from endoderm) (c) Acoelomate

Fig. 32 -9 Protostome development (examples: molluscs, annelids) Deuterostome development (examples: echinoderm, chordates) Eight-cell stage Spiral and determinate Key Radial and indeterminate (b) Coelom formation Coelom Ectoderm Mesoderm Endoderm (a) Cleavage Archenteron Coelom Mesoderm Blastopore Solid masses of mesoderm split and form coelom. Mesoderm Folds of archenteron form coelom. Anus Mouth (c) Fate of the blastopore Digestive tube Mouth develops from blastopore. Anus develops from blastopore.

Fig. 32 -10 “Porifera” Eumetazoa Metazoa ANCESTRAL COLONIAL FLAGELLATE Cnidaria Ctenophora Deuterostomia Ectoprocta Brachiopoda Echinodermata Bilateria Chordata Platyhelminthes Protostomia Rotifera Mollusca Annelida Arthropoda Nematoda

Metazoa Silicea Calcarea Ctenophora Eumetazoa ANCESTRAL COLONIAL FLAGELLATE “Porifera” Fig. 32 -11 Cnidaria Acoela Bilateria Deuterostomia Echinodermata Chordata Platyhelminthes Lophotrochozoa Rotifera Ectoprocta Brachiopoda Mollusca Annelida Ecdysozoa Nematoda Arthropoda

Fig. 32 -UN 1 Common ancestor of all animals Metazoa Sponges (basal animals) Eumetazoa Ctenophora Cnidaria Acoela (basal bilaterians) Deuterostomia Bilateral summetry Three germ layers Lophotrochozoa Ecdysozoa Bilateria (most animals) True tissues