1. Chapter 32: Introduction to Animal Diversity
Animals are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers
The history of animals spans more than 500 million years
Animals can be characterized by “body plans”
New views of animal phylogeny are emerging

2. Some major episodes in the history of life Compare with Table 25
Some major episodes in the history of life Compare with Table 25.1 (The geologic record)

3. 25.7 Clock analogy for some key events in evolutionary history

4. Concept 26.6. Continuous revisions of our understanding of the tree of life.
See also Whittaker, Science (1969)

5. 26. 21. The three domains of life
The three domains of life. Branch lengths are proportional to the amount of genetic change in each lineage. Lineages with multi-cellular organisms shown in red

6. One view of animal diversity based on body-plan grades (compare with 32.10)

7. Kingdom Animalia – general characteristics (and yes, there are exceptions)
Multicellular, heterotrophic eukaryotes
Feed by ingestion
Lack cell walls. Bodies held together by structural proteins embedded in tissues (collagen) and between cells (cadherins)
Presence of nervous and muscle tissue
Store carbohydrate reserves as glycogen
Reproduce sexually with characteristic development of the early embryo
Transformation and development of the zygote controlled by special regulatory genes (Hox genes).

8. 32.2 Early embryonic development in animals

9. 32.2 Early embryonic development in animals

10. 32.2 Early embryonic development in animals

11. 47.8 Cleavage in a frog embryo

12. 47.6 Cleavage in an echinoderm (sea urchin) embryo

13. Sea urchin development, from single cell to larva
Human blastula

14. One view of animal diversity based on body-plan grades (compare with 32.10)

15. 25.10.
The Cambrian explosion:
A relatively short geologic time span (20-40 million years) during which many different phyla of animals suddenly appear in the fossil record (the yellow bars indicate the earliest appearance in the fossil record).
This is an example of “adaptive radiation”, a period of evolutionary change when many new taxa are formed filling new functions in their environment.

16. 32.5 A sample of some of the animals that may have evolved during the Cambrian explosion

17. Burgess Shale fossils (British Columbia)

18. 28.3 A phylogenetic hypothesis of eukaryotes (see book page 578)

19. Protistan Diversity (see book p. 598)

20. 32.3. Evidence that choanoflagellates are closely related to animals
[choano: funnel (Gr.)]
DNA data show that choanoflagellate and animals are sister groups
Similar cells are found in other animals but have never been found in plants, fungi or protists other than choanoflagellates.
Morphologically, choanoflagellate cells are almost identical to the cells of sponges, the most primitive animals

21. One view of animal diversity based on body-plan grades (compare with 32.10)

22. Sponges – Porifera (Calcarea and Silicea) - no true tissues

23. Oral
Aboral
32.7 Body symmetry
Dorsal
Posterior
Ventral
Anterior

24. No symmetry
Radial symmetry
diploblastic
Bilateral symmetry
triploblastic

25. 32.2 Early embryonic development in animals

26. 47.11 Gastrulation in a sea urchin embryo

27. 47.14. Adult derivatives of the three embryonic germ layers in vertebrates

28. One view of animal diversity based on body-plan grades

29. 32.8 Body plans of triploblastic bilateria
‘the rest’
Rotifers
Roundworms
Flatworms

30. One view of animal diversity based on body-plan grades

31. 32.9. A comparison of early development in protostomes and deuterostomes

32. 32.10 New views: One hypothesis of animal phylogeny based on morphological and developmental comparisons

33. Chapter 32 - Review
Animals are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers
The hsistory of animals spans more than 500 million years
Animals can be charaterized by ‘body plans’
New views of animal
phylogeny are merging
from molecular data

34. Organisms showing radial symmetry would likely
be good swimmers.
have rapid escape behavior.
move from place to place relatively slowly, if at all.
be able to fly.
have many fins.