1. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Chapter 32 An Introduction to Animal Diversity

2. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Overview: Welcome to Your Kingdom 1.3 million living species of animals have been identified Video: Coral Reef Video: Coral Reef

3. Fig. 32-1

4. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings There are exceptions to nearly every criterion for distinguishing animals from other life-forms Several characteristics, taken together, sufficiently define the group Concept 32.1: Animal are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers

5. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Nutritional Mode Animals are heterotrophs that ingest their food

6. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cell Structure and Specialization Animals are multicellular eukaryotes Their cells lack cell walls Their bodies are held together by structural proteins such as collagen Nervous tissue and muscle tissue are unique to animals

7. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Reproduction and Development Most animals reproduce sexually, with the diploid stage usually dominating the life cycle After a sperm fertilizes an egg, the zygote undergoes rapid cell division called cleavage Cleavage leads to formation of a blastula The blastula undergoes gastrulation, forming a gastrula with different layers of embryonic tissues Video: Sea Urchin Embryonic Development Video: Sea Urchin Embryonic Development

8. Fig. 32-2-1 Zygote Cleavage Eight-cell stage

9. Fig. 32-2-2 Zygote Cleavage Eight-cell stage Cleavage Blastula Cross section of blastula Blastocoel

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

11. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Many animals have at least one larval stage A larva is sexually immature and morphologically distinct from the adult; it eventually undergoes metamorphosis

12. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings All animals, and only animals, have Hox genes that regulate the development of body form Although the Hox family of genes has been highly conserved, it can produce a wide diversity of animal morphology

13. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 32.3: Animals can be characterized by “body plans” Zoologists sometimes categorize animals according to a body plan, a set of morphological and developmental traits

14. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Symmetry Animals can be categorized according to the symmetry of their bodies, or lack of it Some animals have radial symmetry

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

16. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Two-sided symmetry is called bilateral symmetry 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 © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings END DAY

18. Copyright © 2008 Pearson Education, Inc., publishing as Pearson 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 During development, three germ layers give rise to the tissues and organs of the animal embryo

19. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Ectoderm is the germ layer covering the embryo’s surface Endoderm is the innermost germ layer and lines the developing digestive tube, called the archenteron Diploblastic animals have ectoderm and endoderm Triploblastic animals also have an intervening mesoderm layer; these include all bilaterians

20. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Body Cavities Most triploblastic animals possess a body cavity A true body cavity is called a coelom and is derived from mesoderm Coelomates are animals that possess a true coelom

21. Fig. 32-8a Coelom Body covering (from ectoderm) Digestive tract (from endoderm) Tissue layer lining coelom and suspending internal organs (from mesoderm) (a) Coelomate

22. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings A pseudocoelom is a body cavity derived from the mesoderm and endoderm Triploblastic animals that possess a pseudocoelom are called pseudocoelomates

23. Fig. 32-8b Pseudocoelom Body covering (from ectoderm) Muscle layer (from mesoderm) Digestive tract (from endoderm) (b) Pseudocoelomate

24. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Triploblastic animals that lack a body cavity are called acoelomates

25. Fig. 32-8c (c) Acoelomate Body covering (from ectoderm) Wall of digestive cavity (from endoderm) Tissue- filled region (from mesoderm)

26. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Protostome and Deuterostome Development Based on early development, many animals can be categorized as having protostome development or deuterostome development

27. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cleavage In protostome development, cleavage is spiral and determinate In deuterostome development, cleavage is radial and indeterminate With indeterminate cleavage, each cell in the early stages of cleavage retains the capacity to develop into a complete embryo Indeterminate cleavage makes possible identical twins, and embryonic stem cells

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

29. Fig. 32-9a Eight-cell stage (a) Cleavage Spiral and determinateRadial and indeterminate Protostome development (examples: molluscs, annelids) Deuterostome development (examples: echinoderms, chordates)

30. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Coelom Formation In protostome development, the splitting of solid masses of mesoderm forms the coelom In deuterostome development, the mesoderm buds from the wall of the archenteron to form the coelom

31. Fig. 32-9b Coelom Protostome development (examples: molluscs, annelids) Deuterostome development (examples: echinoderms, chordates) (b) Coelom formation Key Ectoderm Mesoderm Endoderm Mesoderm Coelom Archenteron Blastopore Solid masses of mesoderm split and form coelom. Folds of archenteron form coelom.

32. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fate of the Blastopore The blastopore forms during gastrulation and connects the archenteron to the exterior of the gastrula In protostome development, the blastopore becomes the mouth In deuterostome development, the blastopore becomes the anus

33. Fig. 32-9c Anus Protostome development (examples: molluscs, annelids) Deuterostome development (examples: echinoderms, chordates) Anus Mouth Digestive tube (c) Fate of the blastopore Key Ectoderm Mesoderm Endoderm Mouth develops from blastopore.Anus develops from blastopore.

34. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 32.4: New views of animal phylogeny are emerging from molecular data Current debate in animal systematics has led to the development of two phylogenetic hypotheses, but others exist as well

35. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings One hypothesis of animal phylogeny is based mainly on morphological and developmental comparisons

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

37. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings One hypothesis of animal phylogeny is based mainly on molecular data

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

39. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Points of Agreement All animals share a common ancestor Sponges are basal animals Eumetazoa is a clade of animals (eumetazoans) with true tissues Most animal phyla belong to the clade Bilateria, and are called bilaterians Chordates and some other phyla belong to the clade Deuterostomia

40. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Progress in Resolving Bilaterian Relationships The morphology-based tree divides bilaterians into two clades: deuterostomes and protostomes In contrast, recent molecular studies indicate three bilaterian clades: Deuterostomia, Ecdysozoa, and Lophotrochozoa

41. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Ecdysozoans shed their exoskeletons through a process called ecdysis

42. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Some lophotrochozoans have a feeding structure called a lophophore Other phyla go through a distinct developmental stage called the trochophore larva LophophoreStructure of a trochophore larva Anus Mouth Apical tuft of cilia

43. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Future Directions in Animal Systematics Phylogenetic studies based on larger databases will likely provide further insights into animal evolutionary history

44. Fig. 32-UN1 Common ancestor of all animals True tissues Sponges (basal animals) Ctenophora Cnidaria Acoela (basal bilaterians) Deuterostomia Lophotrochozoa Ecdysozoa Metazoa Eumetazoa Bilateria (most animals) Bilateral summetry Three germ layers