1. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Chapter 32 An Introduction to Animal Diversity

2. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Animal are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers Several characteristics of animals – Sufficiently define the group

3. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Nutritional Mode Animals are heterotrophs – That ingest their food

4. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cell Structure and Specialization Animals are multicellular eukaryotes Their cells lack cell walls

5. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Their bodies are held together – By structural proteins such as collagen Nervous tissue and muscle tissue – Are unique to animals

6. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Reproduction and Development Most animals reproduce sexually – With the diploid stage usually dominating the life cycle

7. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings After a sperm fertilizes an egg – The zygote undergoes cleavage, leading to the formation of a blastula The blastula undergoes gastrulation – Resulting in the formation of embryonic tissue layers and a gastrula

8. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings All animals, and only animals – Have Hox genes that regulate the development of body form

9. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Paleozoic Era (542–251 Million Years Ago) The Cambrian explosion – Marks the earliest fossil appearance of many major groups of living animals Figure 32.6

10. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Mesozoic Era (251–65.5 Million Years Ago) During the Mesozoic era – Dinosaurs were the dominant terrestrial vertebrates – Coral reefs emerged, becoming important marine ecological niches for other organisms

11. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cenozoic Era (65.5 Million Years Ago to the Present) The beginning of this era – Followed mass extinctions of both terrestrial and marine animals Modern mammal orders and insects – Diversified during the Cenozoic

12. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Animals can be characterized by “body plans” One way in which zoologists categorize the diversity of animals – Is according to general features of morphology and development

13. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Symmetry Animals can be categorized – According to the symmetry of their bodies, or lack of it

14. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Some animals have radial symmetry – Like in a flower pot Figure 32.7a Radial symmetry. The parts of a radial animal, such as a sea anemone (phylum Cnidaria), radiate from the center. Any imaginary slice through the central axis divides the animal into mirror images. (a)

15. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Some animals exhibit bilateral symmetry – Or two-sided symmetry Figure 32.7b Bilateral symmetry. A bilateral animal, such as a lobster (phylum Arthropoda), has a left side and a right side. Only one imaginary cut divides the animal into mirror-image halves. (b)

16. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Bilaterally symmetrical animals have – A dorsal (top) side and a ventral (bottom) side – A right and left side – Anterior (head) and posterior (tail) ends – Cephalization, the development of a head

17. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Tissues Animal body plans – Also vary according to the organization of the animal’s tissues Tissues – Are collections of specialized cells isolated from other tissues by membranous layers

18. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Animal embryos – Form germ layers, embryonic tissues, including ectoderm, endoderm, and mesoderm

19. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A true body cavity – Is called a coelom and is derived from mesoderm Figure 32.8a Coelom Body covering (from ectoderm) Digestive tract (from endoderm) Tissue layer lining coelom and suspending internal organs (from mesoderm) Coelomate. Coelomates such as annelids have a true coelom, a body cavity completely lined by tissue derived from mesoderm. (a)

20. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A pseudocoelom – Is a body cavity derived from the blastocoel, rather than from mesoderm Figure 32.8b Pseudocoelom Muscle layer (from mesoderm) Body covering (from ectoderm) Digestive tract (from ectoderm) Pseudocoelomate. Pseudocoelomates such as nematodes have a body cavity only partially lined by tissue derived from mesoderm. (b)

21. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Organisms without body cavities – Are considered acoelomates Figure 32.8c Body covering (from ectoderm) Tissue- filled region (from mesoderm) Digestive tract (from endoderm) Acoelomate. Acoelomates such as flatworms lack a body cavity between the digestive tract and outer body wall. (c)

22. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cleavage In protostome development – Cleavage is spiral and determinate In deuterostome development – Cleavage is radial and indeterminate Figure 32.9a Protostome development (examples: molluscs, annelids, arthropods) Deuterostome development (examples: echinoderms, chordates) Eight-cell stage Spiral and determinate Radial and indeterminate (a) Cleavage. In general, protostome development begins with spiral, determinate cleavage. Deuterostome development is characterized by radial, indeterminate cleavage.

23. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Fate of the Blastopore In protostome development – The blastopore becomes the mouth In deuterostome development – The blastopore becomes the anus Figure 32.9c Anus Mouth Mouth develops from blastopore Anus develops from blastopore Digestive tube

24. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings One hypothesis of animal phylogeny based mainly on morphological and developmental comparisons Figure 32.10 Porifera Cnidaria Ctenophora Phoronida Ectoprocta Brachiopoda Echinodermata Chordata Platyhelminthes Mollusca Annelida Arthropoda Rotifera Nemertea Nematoda “ Radiata ” Deuterostomia Protostomia Bilateria Eumetazoa Metazoa Ancestral colonial flagellate

25. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings One hypothesis of animal phylogeny based mainly on molecular data Figure 32.11 Calcarea Silicarea Ctenophora Cnidaria Echinodermata Chordata Brachiopoda Phoronida Ectoprocta Platyhelminthes Nemertea Mollusca Annelida Rotifera Nematoda Arthropoda “Radiata” “Porifera” Deuterostomia Lophotrochozoa Ecdysozoa Bilateria Eumetazoa Metazoa Ancestral colonial flagellate

26. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Points of Agreement All animals share a common ancestor Sponges are basal animals Eumetazoa is a clade of animals with true tissues

27. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Most animal phyla belong to the clade Bilateria Vertebrates and some other phyla belong to the clade Deuterostomia

28. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ecdysozoans share a common characteristic – They shed their exoskeletons through a process called ecdysis Figure 32.12

29. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Lophotrochozoans share a common characteristic – Called the lophophore, a feeding structure Figure 32.13a, b Apical tuft of cilia Mouth Anus (a) An ectoproct, a lophophorate (b)Structure of trochophore larva