5.5: Classification Topic 5: Ecology & Evolution Miss Friedman

5.5.1: Binomial system of nomenclature ► Designed by Carolus Linneaus in 18 th 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

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

► 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: 1. Kingdom 2. Phylum 3. Order 4. Family 5. Genus 6. Species

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

► Need to know: -Bryophyta -angiospermophyta -Filicinophyta -Coniferophyta -Filicinophyta -Coniferophyta

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.

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

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)

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

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

► 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.

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

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 CaCO 3 skeleton

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

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

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.

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

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