Intro to Animal Diversity

1. Intro to Animal Diversity Chapter 32

2. Animalia – General Notes • 1.3 million species • 300K plant species • 1.5 million fungi • >10 million bacteria • Animals ARE heterotrophs • Plantae? Fungi? Protista? • Animals are multicellular • Plantae? Fungi? Protista? Bacteria?

3. Animalia – General (Page 2) • Unique in the possession of muscular and nervous tissue • Lack cell walls • Held together by structural proteins such as collagen • Plants? Fungi? Bacteria? Protista? • Most reproduce sexually • Diploid stage is dominant in most

4. Fertilization  Zygote  (Mitosis) Cleavage  Blastula

5. Embryology Notes • Cleavage – rapid series of mitotic divisions w/o cell growth in between • What part(s) of the cell cycle would be proportionally reduced during cleavage? Extended? • Blastula – Hollow ball of cells • Cavity is called blastocoel • Gastrula – blastula gets “punched in” • Embryonic tissue layers form from gastrulation • Product of gastrulation called archenteron • Blastophore is the opening of the archenteron

6. 2 Quick Things • Some animals have a larval stage • Immature, distinct form • Undergoes metamorphosis to become adult form • Hox genes • Common in animals • Genes that play an important role in development

7. Animal Body Plans • There are 3 main types of animal body plans: • No symmetry • Sponges • Radial symmetry • Jellyfish and many primitive animals • Central axis, and any cut through the axis results in mirror images

9. Bilateral Symmetry • Most amphibians, reptiles, birds, and mammals • Produces a right and left sides that are mirror images of each other • Usually produces dorsal and ventral sides • Associated with cephalization • Anterior (head) end • Posterior (tail) end • Concentration of sensory equipment at one end • Usually anterior end

10. Coelomate • True coelom • Fluid-filled body cavity between digestive tract & outer body wall • True compartmentalization • Pseudocoelomate • Triploblastic animals • -- 3 tissue layers • Cavity formed from mesoderm + endoderm • Acoelomate •  No cavity between alimentary canal and outer body wall

11. Germ Layers • Give rise to the tissues and organs of the animal embryo • 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

12. Germ Layers • Diploblastic animals have ectoderm and endoderm • Triploblasticanimals also have an intervening mesoderm layer; these include all bilaterians • A pseudocoelom is a body cavity derived from the mesoderm and endoderm

13. Why a body cavity (coelom)? • The separation between body wall and digestive tract have advantages • Cushion suspended organs • From blunt force and other sources of physical trauma • Increased structural support • Skeletal structure or hydrostatic skeleton • Internal organs grow and move independently • Greater specialization = more advanced

15. 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

16. Fate of the Blastophore • The blastoporeforms 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