5.5: Classification

1. 5.5: Classification Pp 142 - 149

2. Binomial system of nomenclature • System of assigning scientific/binomial names to organisms designed by CarolusLinneaus 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: Binomial name for Humans is Homo sapiens

3. Hierarchy of Taxa • Taxonomy is the study of classification • Organisms are placed in groups based on similarities & differences • Organisms that share characteristics are placed into similar groups • The more similar their characteristics, the closer the grouping • Taxon (plural:taxa)is a group/unit in a classification system • There are seven taxonomic units: • Kingdom • Phylum • Order • Family • Genus • Species

6. Kingdom Plantae Phylum Bryophyta Phylum Filicinophyta Phylum Angiospermohyta Phylum Coniferohyta

7. 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

8. Using external recognition features only, distinguish between the following phyla of kingdom plantae: bryophyta, fillicinophyata, coniferophyta & angiospermophyta

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

10. 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.

11. Phylum: Filicinophyta(ferns) • Have true leaves in fronds • New leaves unroll • Divided leaves • There is cuticle on leaves • Have an underground creeping stem (rhizome) • Height up to 20m but not woody • Reproduction: sporangia (sori) contain reproductive spores

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

13. Phylum: Angiospermophyta (flowering plants and grasses) • Differentiated into roots, stem, leaves & flowers • Have flowers, although they may be small in wind-pollinated angiospermophyta • Seeds produced in 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

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

15. Distinguish between the following phyla of animals, using simple external recognition features: porifera, cnidaria, platyhelminthes, annelida, molluscaandarthropoda.

16. 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 parts • 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.

17. Phylum: Porifera(sponges) • no clear symmetry • 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 i.e. they are attached to a surface • Body plan is built around water canals that circulate nutrients through the sponge for ingestion by specialized cells • There is no mouth or anus

18. Phylum: Cnidaria(Jelly fish, Sea anemones, Corals) • Body has radial symmetry • They have two layers in the body plan • Jelly fish are mobile organisms. Sea anemones are sessile organisms • Single entrance that serves the cavity & functions as circulation of respiratory gases and nutrients i.e. they have mouth but no anus • Have tentacles & stinging cells • These organisms are secondary consumers and posses stinging cells with toxins called nematocysts to disable prey • Corals secrete a CaCO3 skeleton

19. Phylum: Platyhelminthes(flatworms) • 3 layers in the body plan • bilateral symmetry • unsegmented, flat body • One entrance to “gut” which can have many folds to increase surface area i.e. have mouth, but no anus • Largely parasitic, includes flukes

20. 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

21. Phylum: Mollusca(Snails, Slugs, Octopus) • Bilateral symmetry with significant modification • Have mouth and anus • 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 gill. The mantle frequently secretes a calcareous shell.

22. 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

23. 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

24. Revision Questions • Outline the binomial system of nomenclature. • List down the seven levels in the hierarchy of taxa. • Using simple external recognition features, distinguish between the following phyla of kingdom plantae: bryophyta, filicinophyta, coniferophytaand angiospermophyta. • Using simple external recognition features, distinguish between the following phyla of kingdom animalia: porifera, cnidaria, platyhelminthes, annelida, molluscaand arthropoda.

25. Using observable characteristics only, design a dichotomous key for identifying the following arthropods.