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.