Zoology as a part of Biology

1. Zoology as a part of Biology • Zoology is the study of animals • Characteristics of animals: • A branch of the evolutionary tree of life • Part of a large limb of eukaryotes (organisms with nuclei in cells) • Unique in nutrition – heterotrophs (eat other organisms and need to capture food) • Not capable of photosynthesis. Lack cell walls.

2. Zoology • A broad field with many subdisciplines • Examples: • Cytology – structure and function of cells • Histology – tissues • Parasitology – animals that live in or on other organisms, at the expense of the host. • Ichthyology – study of fishes See Tables 1.1 and 1.2 in text

3. Zoology: An Evolutionary Perspective • An understanding of evolutionary processes allows us to explain the family relationships among animals and how the great variety of animals arose. • Evolutionary process have resulted in an estimated 4 to 100 million species of animals living today.

4. Zoology: An Evolutionary Perspective • Organic evolution: change in population of organisms over time • Source of animal diversity and explains family relationships within animal groups • Groups of individuals are more closely related if they share more of their DNA with each other than with individuals in other groups.

5. Zoology: An Ecological Perspective • Ecology: study of the relationships between organisms and their environment. • Two main problems of concern: • 1. Global overpopulation (Most growth in less developed countries) • 2. Exploitation of world resources (Oil production, fossil fuels, deforestation, etc)

6. Zoology: An Ecological Perspective • Solutions: • Better understanding of basic ecological principles • Must work to prevent spread of disease, famine, etc • Better resource management

7. Animal Systematics • Goal of animal systematics: • To arrange animals into groups that reflect evolutionary relationships

8. Animal Systematics • Phylogeny: Also known as evolutionary tree. Based on characters that vary among species. • Character: anything that has a genetic basis and can be measured.

9. Patterns of Organization Symmetry vs. Asymmetry Symmetry: describes how parts of an animal are arranged around a point or axis. Asymmetry: absence of a central point of axis.

10. Patterns of Organization • Types of symmetry: 1. Radial: any plane passing through the central axis divides the animal into mirror images. 2. Bilateral: a single plane, passing through the longitudinal axis of an animal, divides the animal into right and left mirror images.

11. Radial Symmetry

12. Bilateral Symmetry

13. Terms of Direction • Table 7.3 • Aboral – end opposite the mouth • Oral – end containing the mouth • Anterior – head end • Posterior – tail end • Caudal – toward the tail • Cephalic – toward the head

14. Terms of Direction • Table 7.3 (cont’d) • Distal – Away from point of attachment • Proximal – Toward the point of attachment • Dorsal – Back of an animal (synonymous with posterior for upright animals) • Ventral – Belly of an animal (synonymous with anterior for upright animals)

15. Terms of Direction • Table 7.3 (cont’d) • Inferior – Below a point of reference • Superior – Above a point of reference • Lateral – Away from the plane that divides a bilateral animal • Medial – On or near the plane that divides a bilateral animal

16. Other Patterns of Organization • Unicellular Level of Organization • Protista • Diploblastic Organization • Body parts organized into layers derived from two tissue layers • Ectoderm – gives rise to epidermis • Endoderm – gives rise to gastrodermis • Jellyfish, Hydra

17. Other Patterns of Organization • Triploblastic Animals • Tissues derived from three embryonic layers • Ectoderm • Mesoderm – found in middle. Gives rise to supportive, contractile, and blood cells. • Endoderm

18. Other Patterns of Organization • Triploblastic Animals (cont’d) • Organized based on the presence or absence of body cavity • Body Cavity – fluid-filled space in which internal organs can be suspended and separated from body wall.