5.5: Classification

1. 5.5: Classification Topic 5: Ecology & Evolution Miss Friedman

2. 5.5.1: Binomial system of nomenclature • Designed by Carolus Linneaus in 18th century • Based on idea that every species has a Latin name, made up of two parts • First part is the name of the genus • Second part specifies the species • Name should be printed in italics (underlined if hand written) and first part capitalized Example Humans are Homo sapiens

3. 5.5.2: Hierarchical system of classification • Organisms that share characteristics are placed into similar groups • The more similar their characteristics, the closer the grouping • The purpose of classification is to: • Clearly identify an organism with a name that is unique to the species and avoids confusion with local naming • Show evolutionary links • Allow us to predict anatomical, physiological and genetic characteristics it may share with other organisms

4. The Hierarchical system has seven levels called taxons (plural: taxa) • Each taxon can contain one or more of the sub-group below it • The seven level hierarchies of taxa are: • Kingdom • Phylum • Order • Family • Genus • Species

6. 5.5.3: Plant Phyla • Kingdom: Plantae • Characteristics: • Photosynthetic • Chlorophyll • Cellulose cell wall • Permanent vacuoles • Stores starch • Classification of the major plant phyla is based on external observables structures

7. Need to know: -Bryophyta -angiospermophyta -Filicinophyta -Coniferophyta

8. Phylum: Bryophyta (Mosses, Liverworts, Hornworts) • Small terrestrial plants • Do not have true roots, stems or leaves but they must have structures resembling them • Leaf-like structures are often arranged in a spiral • Usually have live in clusters which act like sponges holding water • No cuticle • Reproductive structures are called sporangium which is on long stalks with capsules on end.

9. Phylum: Filicinophyta (ferns) • Have true leaves • New leaves unroll • Divided leaves • Have an underground creeping stem (rhizome) • Height up to 20m • Reproduction: sporangia (sori) contain reproductive spores

10. Phylum: Coniferophytes(conifers & pines) • All conifers are woody plants, most are trees with a single wooden trunk with side branches • Leaves are waxy, long thin needles, often arranged in spirals, often a dark green colour • Produce seeds found in cones • Vascular system (tracheids)

11. Phylum: Angiospermophyta(flowering plants and grasses) • Have flowers, although they may be small in wind-pollinated angiospermophyta • Seeds are ovaries which become the fruit • Leaves usually as leaf blade and leaf stalk, with veins visible on the lower surface • Leaves have waxy cuticle • Vascular bundles (veins) are made up of xylem & phloem

12. 5.5.4: Animal phyla • The kingdom of animals is classified according to these characteristics: • Heterotrophic • No cell walls • No vacuoles • No chlorophyll • Store glycogen

13. The syllabus specifies 6 of the 30 or more phyla from the animal kingdom that you are responsible for knowing • The ones selected are what might be called invertebrates (lack of a spinal cord) • The six phyla are classified according to features such as: • Number of layers in the body plant • The opening for mouth and anus • Method of support Phylogenic studies (evolutionary relationship) relies on more genetic studies to support the modern classification of these groups.

14. Phylum: Porifera (sponges) • No body layer, rather there is an aggregate of different cell types • Support is from either silica or calcium based spicules which link together to provide some support • Body plan is built around water canals that circulate nutrients through the sponge for ingestion by specialized cells • There is no mouth or anus

15. Phylum: Cnidaria (Jelly fish, Sea anemones, Corals) • They have two layers in the body plan • There is radial symmetry • Jelly fish are mobile organisms. Sea anemones are sessile organisms • Single entrance that serves the cavity that functions as circulation of respiratory gases and nutrients • These organisms are secondary consumers and posses stinging cells with toxins called nematocysts to disable prey • Corals secrete a CaCO3 skeleton

16. Phylum: Platyhelminthes (flatworms) • 3 layers in the body plan • One entrance to “gut” which can have many folds to increase surface area. • Largely parasitic, includes flukes

17. Phylum: Annelida (segment worms) • 3 layers to the body plan • Bilateral symmetry • Body is divided into ringed segments with some specialization of segments • Mouth is connected via gut to a separate anus • Skin surface is used for gas exchange • Many marine forms but also terrestrial species, usually soil burrowing

18. Phylum: Mollusca(Snails, Slugs, Octopus) • Bilateral symmetry with significant modification • Body plan has three major features • Foot, a muscular structure used for movement and burrowing • Central visceral mass, contains all the organ structures (separate mouth & anus) • Mantle, a folded membrane structure that can surround other tissues and create a cavity containing ag ill. The mantle frequently secretes a calcareous shell.

19. Phylum: Arthropoda(Insects, Crustaceans, Spiders, Scorpions, Millipedes) • 3 layer body plant with bilateral symmetry • Hard exoskeleton composed of chitin • Jointed body segments • Jointed appendages to each segment • At least 3 pairs of jointed legs • Some flying organisms in the class Insecta • Separate mouth and anus • Many free-living but also some parasitic

20. 5.5.5: Dichotomous Keys • Each questions divides the group of organisms into two smaller groups based on a pair of alternative characteristics • Subsequent groups may focus on more minor details • In most cases the characteristic will be readily observed or measurable • It is better to choose characteristics that are uninfluenced by environmental variation • Shape and number are often good characteristics on which to base alternative pairings • A complete key will have each type of organisms being classified separated with a final identifying name