Chapter 32: Introduction to Animal Diversity 32.1. Animals are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers 32.2. The history of animals spans more than 500 million years 32.3. Animals can be characterized by “body plans” 32.4. New views of animal phylogeny are emerging

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)

25.7 Clock analogy for some key events in evolutionary history

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

26. 21. The three domains of life 26.21. 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

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

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).

32.2 Early embryonic development in animals

32.2 Early embryonic development in animals

32.2 Early embryonic development in animals

47.8 Cleavage in a frog embryo

47.6 Cleavage in an echinoderm (sea urchin) embryo

Sea urchin development, from single cell to larva Human blastula http://www.bioclips.com/dvd/movies/signals10.html

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

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.

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

Burgess Shale fossils (British Columbia)

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

Protistan Diversity (see book p. 598)

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

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

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

Oral Aboral 32.7 Body symmetry Dorsal Posterior Ventral Anterior

No symmetry Radial symmetry diploblastic Bilateral symmetry triploblastic

32.2 Early embryonic development in animals

47.11 Gastrulation in a sea urchin embryo

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

One view of animal diversity based on body-plan grades

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

One view of animal diversity based on body-plan grades

32.9. A comparison of early development in protostomes and deuterostomes

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

Chapter 32 - Review 32.1. Animals are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers 32.2. The hsistory of animals spans more than 500 million years 32.3. Animals can be charaterized by ‘body plans’ 32.4. New views of animal phylogeny are merging from molecular data

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.