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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 years32.3. 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 25.1 (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. 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
http://www.bioclips.com/dvd/movies/signals10.htmlHuman blastula
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)
28.3A 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.)]
Morphologically, choanoflagellate cells are almost identical to the cells of sponges, the most primitive animals
Similar cells are found in other animals but have never been found in plants, fungi or protists other than choanoflagellates.
DNA data show that choanoflagellate and animals are sister groups
One view of animal diversity based on body-plan grades(compare with 32.10)
Sponges – Porifera (Calcarea and Silicea) - no true tissues
32.7 Body symmetry
Oral
Aboral
Dorsal
Ventral
Posterior
Anterior
No symmetry Radial symmetrydiploblastic
Bilateral symmetrytriploblastic
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
Flatworms
RotifersRoundworms
‘the rest’
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
a) be good swimmers.
b) have rapid escape behavior.
c) move from place to place relatively slowly, if at all.
d) be able to fly.
e) have many fins.
