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Chapter 32 An Introduction to Animal Diversity

Chapter 32 An Introduction to Animal Diversity. What is an animal? Multicellular, heterotrophic eukaryote – ingestion Structural support from structural proteins – NOT cell walls Nervous tissue & muscle tissue for impulse conduction & movement

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Chapter 32 An Introduction to Animal Diversity

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  1. Chapter 32 An Introduction to Animal Diversity • What is an animal? • Multicellular, heterotrophic eukaryote – ingestion • Structural support from structural proteins – NOT cell walls • Nervous tissue & muscle tissue for impulse conduction & movement • Sexual reproduction with motile sperm swimming to non-motile egg • How did animals evolve? • - Current animal development

  2. Cleavage Zygote Eight-cell stage Figure 32.2 Early embryonic development in animals (layer 1) Cleavage – cell division w/out cytokinesis - More cells but same total volume – no cell growth

  3. Blastocoel Cleavage Cleavage Cross section of blastula Zygote Eight-cell stage Blastula Figure 32.2 Early embryonic development in animals (layer 2) Blastula – hollow ball of cells -coel – opening or cavity

  4. Blastocoel Cleavage Cleavage Cross section of blastula Zygote Eight-cell stage Blastula Blastocoel Endoderm Ectoderm Gastrula Gastrulation Blastopore Figure 32.2 Early embryonic development in animals (layer 3) Gastrulation – movement of cells to form 2 layers Blastopore – opening where cells move into Ectoderm – outside layer Endoderm – inside layer

  5. Chapter 32 An Introduction to Animal Diversity • What is an animal? • Multicellular, heterotrophic eukaryote – ingestion • Structural support from structural proteins – NOT cell walls • Nervous tissue & muscle tissue for impulse conduction & movement • Sexual reproduction with motile sperm swimming to non-motile egg • How did animals evolve? • Current animal development • Current hypothesis

  6. Digestive cavity Somatic cells Reproductive cells Hollow sphereof unspecialized cells (shown in cross section) Colonial protist, an aggregate of identical cells Beginning of cell specialization Infolding Gastrula-like “protoanimal” Figure 32.4 One hypothesis for the origin of animals from a flagellated protist

  7. Radial Bilateral Chapter 32 An Introduction to Animal Diversity • What is an animal? • How did animals evolve? • How are animals grouped & characterized? • Body plans • Symmetry • None (sponge) • Radial • multiple central axis “cuts” provide mirror images • Only have top & bottom • Bilateral • Only 1 central axis “cut” provides a mirror image • Has top, bottom, left & right

  8. H-W Lab • All 6 sections • Personal Acct • Data for all 3 Cases including NEW p & q • Discussion questions for all 3 Cases • 6 practice problems at the end • Not Exercise 8A or Case IV • Protist ID Lab • -All 6 sections • -Pre-lab from in-class notes • -Personal acct • -include characteristics that you keyed out • -name of organism • -drawing of organism

  9. Chapter 32 An Introduction to Animal Diversity • What is an animal? • How did animals evolve? • How are animals grouped & characterized? • Body plans • Symmetry & TISSUES • None (sponge) • Radial • multiple central axis “cuts” provide mirror images • Only have top & bottom • Diploblastic – 2 cell layers • Ectoderm • Endoderm • Bilateral • Only 1 central axis cut provides a mirror image • Has top, bottom, left & right • Triploblastic – 3 cell layers • Ectoderm & endoderm • Mesoderm – in between ecto- & endoderm • Cephalization – movement of sensory equipment towards the • anterior end of the organism – associated with movement

  10. Chapter 32 An Introduction to Animal Diversity • What is an animal? • How did animals evolve? • How are animals grouped & characterized? • Body plans • Symmetry & tissues • Body cavities • Acoelomates – without a body cavity • Pseudocoelomates – “false body cavity” – cavity not completely • lined with tissue derived from mesoderm • Coelomates – body cavity completely lined with tissue • from mesoderm

  11. Coelom Body covering (from ectoderm) (a) Coelomate. Coelomates such as annelids have a true coelom, a body cavity completely lined by tissue derived from mesoderm. Tissue layer lining coelom and suspending internal organs (from mesoderm) Digestive tract (from endoderm) Body covering (from ectoderm) (b) Pseudocoelomate. Pseudocoelomates such as nematodes have a body cavity only partially lined by tissue derived from mesoderm. Muscle layer (from mesoderm) Pseudocoelom Digestive tract (from ectoderm) Body covering (from ectoderm) Tissue- filled region (from mesoderm) (c) Acoelomate. Acoelomates such as flatworms lack a body cavity between the digestive tract and outer body wall. Digestive tract (from endoderm) Figure 32.8 Body plans of triploblastic animals

  12. Chapter 32 An Introduction to Animal Diversity • What is an animal? • How did animals evolve? • How are animals grouped & characterized? • Body plans • Symmetry & tissues • Body cavities • Developmental plan • Protostome • Deuterostome

  13. Protostome development (examples: molluscs, annelids, arthropods) Deuterostome development (examples: echinoderms, chordates) (a) Eight-cell stage Eight-cell stage Cleavage. In general, protostome development begins with spiral, determinate cleavage. Deuterostome development is characterized by radial, indeterminate cleavage. Spiral and determinate Radial and indeterminate (b) Coelom Coelom formation. Coelom formation begins in the gastrula stage. In protostome development, the coelom forms from splits in the mesoderm (schizocoelous development). In deuterostome development, the coelom forms from mesodermal outpocketings of the archenteron (enterocoelous development). Archenteron Coelom Mesoderm Blastopore Mesoderm Blastopore Schizocoelous: solid masses of mesoderm split and form coelom Enterocoelous: folds of archenteron form coelom (c) Mouth Anus Fate of the blastopore. In protostome development, the mouth forms from the blastopore. In deuterostome development, the mouth forms from a secondary opening. Digestive tube Mouth Anus Anus develops from blastopore Mouth develops from blastopore Figure 32.9 A comparison of protostome and deuterostome development

  14. Rotifera Porifera Cnidaria Annelida Mollusca Chordata Nemertea Nematoda Phoronida Ectoprocta Arthropoda Ctenophora Brachiopoda Echinodermata Platyhelminthes “Radiata” Deuterostomia Protostomia Bilateria Eumetazoa Metazoa Ancestral colonial flagellate Figure 32.10 One hypothesis of animal phylogeny based mainly on morphological and developmental comparisons

  15. Rotifera Cnidaria Silicarea Chordata Annelida Calcarea Mollusca Nemertea Nematoda Phoronida Ectoprocta Arthropoda Ctenophora Brachiopoda Echinodermata Platyhelminthes “Radiata” Deuterostomia Lophotrochozoa Ecdysozoa “Porifera” Bilateria Eumetazoa Metazoa Ancestral colonial flagellate Figure 32.11 One hypothesis of animal phylogeny based mainly on molecular data

  16. Figure 32.12 Ecdysis Ecdysozoa – secrete an exoskeleton and molt Nematoda & Arthropoda

  17. Apical tuft of cilia Mouth 100 m Anus (b) Structure of trochophore larva (a) An ectoproct, a lophophorate Figure 32.13 Characteristics of lophotrochozoans

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