Classification of Organisms HW:

Taxonomy The assignment of a distinctive name to each of the groups in a classification system.

Animal Systematics What is systematics? The study of the kinds and diversity of organisms and the evolutionary relationships among them.

Three schools of Systematics 1. Evolutionary Systematics: Grouping based on evolutionary relationships. Homologous and analogous relationships are both important. 2. Cladistics: Grouping also based on evolutionary relationships. Only homologous relationships are important. 3. Numerical Systematics: Grouping based on math models and the number/proportion of characteristics per animal.

Classification System (Modern) Seven levels of classification (taxa) (Domain) 1. Kingdom 2. Phylum 3. Class 4. Order 5. Family 6. Genus 7. Species

Classification System (Modern) Taxa begin with the largest, broadest groups to the smaller, more specific groups.

5 Kingdoms (recently updated to 6) 1. Monera (a. Eubacteria; b.Archaebacteria)  2. Protista  3. Fungi  4. Plantae  5. Animalia  

Binomial Nomenclature – Universal Naming system A scientific name of an organism contains two parts. The first name is the genus name and the second name is the species name. Here are some simple rules in writing a scientific name: 1. The first letter of the Genus name must be capitalized. 2. The first letter of the species name is not capitalized. 3. Both names must be underlined or italicized.

Evolutionary Relationships Homologous features: characteristics/structures that have a similar origin but different function. Ex.

Evolutionary Relationships Analogous features: characteristics/structures that have different origins but the same function. Ex.

Common Classification Terms Key: a structural map of taxa. Used to place an animal into the correct group by successfully eliminating choices.

Common Classification Terms Symmetry: the layout of an animal’s body 1. Asymmetrical: no noticeable pattern or shape, irregular 2. Radially symmetrical: circular or tubular pattern. Cut halves look similar. 3. Bilaterally symmetrical: Left side a mirror image of the right side down a longitudinal plane.

Common Classification Terms Body Cavities CP 66 1. Acoelomate – no body cavity 2. Pseudocoelomate – (false body cavity) an unlined body cavity 3. True coelomate - a body cavity lined with peritoneum.

Common Classification Terms Digestive systems 1. Two-way digestive system: only has one opening (mouth) for food to enter and wastes to exit. 2. One-way digestive system: have two openings (mouth, anus) for food to enter and wastes to exit.

Common Classification Terms Circulatory systems 1. Open system: has blood vessels that are not interconnected. Blood empties into cavities or sinuses. 2. Closed system: has blood vessels that are interconnected in which blood continuously flows.

Common Classification Terms Skeleton 1. Hydrostatic pressure – body fluids support body 2. Exoskeleton – skeleton covering body tissue. 3. Endoskeleton – body tissue covers the skeleton.

Common Classification Terms Movement 1. Sessile: attached to one place; rarely move 2. Free floating: able to move but lack control of direction 3. Mobile: able to control movements.