Transcript 5.5: Classification - bio

5.5: Classification
Topic 5: Ecology & Evolution
Miss Friedman
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
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
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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.
2.
3.
4.
5.
6.
Kingdom
Phylum
Order
Family
Genus
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
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 CaCO3 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
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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