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Classification of Organisms

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Title: Classification of Organisms


1
Classification of Organisms
2
Classification of Organisms
  • The study of the kinds and diversity of organisms
    and their evolutionary relationships is called
    systematics or taxonomy
  • Taxonomy is the work involved in the original
    description of a species.
  • Systematics is the assigning of species into
    evolutionary groups.

3
Father of Modern Classification
  • The modern classification system originated with
    the work of Carolus Linnaeus
  • he recognized the different species could be
    grouped into broader categories based on shared
    characteristics
  • any grouping of animals that shares a particular
    set of characteristics forms an assemblage called
    a taxon

4
Modern taxonomists use 7 taxa
  • kingdom, phylum, class, order, family, genus and
    species
  • as taxa increase organisms get more specific

5
Binomial Nomenclature
  • when a species is talked about only the genus and
    species names are used
  • this is called the scientific name
  • unique to each type of organism
  • Required by the International Code of Zoological
    Nomenclature

6
Writing Scientific Names
  • the genus names is always capitalized
  • both names are either italicized or underlined
  • leave a space in the underline between names
  • ex. Homo sapien
  • Felis leo
  • Quercus rubra

7
Kingdoms of Life
  • In 1969, Robert H. Whitaker classified kingdoms
    based on cellular organization and mode of
    nutrition
  • this lead to the formation of the 5 kingdoms

8
5 Kingdoms of Classification
  • Monera comprised of bacteria and cyanobacteria
  • distinguished by being single cell prokaryotes
  • Protista comprised of Amoeba, Paramecium etc.
  • distinguished by being single celled eukaryotes
  • Plantae multi-cellular photosynthetic eukaryotes
  • plants have cell walls and are non-motile

9
5 Kingdoms of Classification
  • Fungi multi-cellular heterotrophic eukaryotes
  • fungi have cell walls and usually non-motile
  • digest organic matter extra-cellularly (outside
    of cell) and absorb the breakdown products
  • Animalia multi-cellular heterotrophic
    eukaryotes
  • animal cells lack a cell wall and usually motile
  • feed by ingesting other organisms or parts of
    other organisms

10
Monera prokaryote single-cell
Protista eukaryote multi-cell
Plantae eukaryote multi-cell autotrophic
Fungi eukaryote multi-cell heterotrophic,
external digestion
Animalia eukaryote multi-cell heterotrophic,
internal digestion
11
DOMAINS???
  • Many taxonomists have pushed the idea that the
    five kingdom system isnt enough
  • they feel that organisms share too much
    similarities and need to be grouped otherwise
  • the push has led to the addition of 3 domains

12
3 Domains
  • Archae bacteria that live in extreme conditions
  • Eubacteria true bacteria
  • Eukarya all eukaryotic organisms

13
Patterns of Organization
  • Once the kingdom of an organism has been decided
    other aspects of the organism must be looked at
    to determine its classification
  • Symmetry describes how the parts of an animal
    are arranged around a point or an axis

14
Types of symmetry
  • Asymmetry the absence of a central point or
    axis around which body parts are equally
    distributed
  • characterizes most protists and many sponges
  • not known to be an adaption or advantage to
    anything
  • organisms do not develop complex communication,
    sensory, or locomotor functions

15
Types of symmetry
  • Radial Symmetry arrangement of body parts such
    that any plane passing through the central
    oral-aboral axis divides the animal into mirror
    images
  • oral-aboral axis one point of reference is the
    mouth (oral end) and a second point of reference
    is the end opposite the mouth (aboral end)
  • often modified by the arrangement of some
    structures in pairs , or in other combinations,
    around the central oral-aboral axis

16
Types of symmetry
  • Bilateral Symmetry the arrangement of body
    parts such that a single plane, passing between
    upper and lower surfaces and through the
    longitudinal axis of an animal, divides the
    animal into right and left mirror images.
  • characteristic of active, crawling, or swimming
    animals
  • tend to move in one direction, so one end is
    generally more complex
  • Cephalization the development or formation of a
    distinct head

17
  • Planes of symmetry are used to describe the
    organisms based on the relationships of body
    parts
  • Not all animals are easily described and can be
    confusing if different people try to explain them
    differently
  • To make it simpler some terms have been
    universally adopted.

18
Terms of Directions
  • Aboral the end opposite the mouth
  • Oral the end containing the mouth
  • Anterior the head end usually the end of a
    bilateral animal that meets its environment
  • Posterior the tail end
  • Caudal toward the tail
  • Cephalic toward the head
  • Distal away from the point of attachment
    of a structure on the body (the toes are
    distal to the knee)

19
Terms of Directions
  • Proximal toward the point of attachment of a
    structure on the body (the hip is proximal
    to the knee)
  • Dorsal the back of an animal usually the
    upper surface synonymous with posterior for
    animals that walk upright
  • Ventral the belly of an animal usually the
    lower surface synonymous with anterior for
    animals that walk upright
  • Inferior below a point of reference (the mouth
    is inferior to the nose in humans)
  • Superior above the point of reference (the
    neck is superior to the chest)
  • Lateral away from the plane that divides a
    bilateral animal into mirror images
  • Medial (median) on or near the plane that
    divides a bilateral animal into mirror images

20
Other Patterns of Organization
  • Unicellular (Cytoplasmic) level all single
    celled organisms
  • characteristic body plan of the Protista
  • is not simple
  • must provide for locomotion, food acquisition,
    digestion, water and ion regulation, sensory
    perception, and reproduction all in a single cell
  • colonies can exist, but show little signs of
    interdependence, cooperation, or coordination of
    function

21
Other Patterns of Organization
  • Diploblastic Organization simplest tissue-level
    organization
  • tissue is derived from two embryonic layers
  • Ectoderm gives rise to the epidermis, the outer
    layer of the body wall
  • composed of epithelial and muscular cells
  • Endoderm gives rise to the gastrodermis, the
    tissue that lines the gut cavity
  • composed of digestive and muscular cells
  • between the epidermis and gastrodermis is the
    mesoglea, a noncellular layer
  • cells in each layer are functionally
    interdependent

22
Other Patterns of Organization
  • Triploblastic Organization tissues are derived
    from three embryological layers
  • like diploblastic, the ectoderm forms the outer
    layer and the endoderm lines the gut
  • in between these two layers is the mesoderm
    which gives rise to supportive, contractile, and
    blood cells
  • most organisms have organ-system level of
    organization

23
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24
Triploblastic Subgroups
  • Based on the presence of and what kind of body
    cavity they have.
  • Body Cavity a fluid-filled space in which the
    internal organs can be suspended and separated
    from the body wall

25
Why are Body Cavities advantageous?
  1. Provide more room for organ development.
  2. Provide more surface area for diffusion of gases,
    nutrients, and wastes into and out of organs
  3. Provide and area for storage.
  4. Often act as hydrostatic skeletons.
  5. Provide a vehicle for eliminating wastes and
    reproductive products from the body
  6. Facilitate increased body size.

26
Triploblastic Subgroups
  • Triploblastic Acoelemate Pattern the mesoderm
    layer is a relatively solid mass of cells between
    ectodermal and endodermal layers
  • acoelemate means without a cavity
  • some of the mesodermal cells are parenchyma
    loosely organized cells not specialized for a
    specific function

27
Triploblastic Subgroups
  • Triploblastic Pseudocoelemate Pattern
  • pseudocoelom a body cavity not entirely lined by
    mesoderm
  • No muscular or connective tissues are associated
    with the gut tract
  • No mesodermal sheet covers the inner surface of
    the body wall
  • No membranes suspend organs in the body cavity

28
Triploblastic Subgroups
  • Triploblastic Coelemate Pattern
  • coelem a body cavity completely surrounded by
    mesoderm
  • peritoneum thin mesodermal sheet that lines the
    inner body wall .
  • serosa thin mesodermal sheet that lines the
    outside of visceral organs.
  • peritoneum and serosa are continuous and suspend
    visceral organs in the body cavity.
  • mesentery the suspending sheets of organisms.

29
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30
Three major groups of the Animal Kingdom
  • Mesozoa includes phylum Mesozoa, or the
    mesozoans
  • Parazoa includes phylum Porifera, or the
    sponges
  • Eumetazoa includes all other phyla
  • Eumetazoa are further divided into two groups
    based on body symmetry
  • Radiata animals that have radial symmetry
  • Bilateria animals that have bilateral symmetry

31
  • Bilateria animals are divided into two group
    based on embryological characteristics
  • Comparative Embryology studies based on the
    observation that embryological events may be
    similar because of shared ancestry

32
Two Bilateria Groups
  1. Protostomes include animals in the phyla
    Platyhelminthes, Nematoda, Mollusca, Annelida,
    Arthropoda, and others
  2. Deuterstomes include animals in the phyla
    Echinodermatat, Hemichrodata, Chordata, and
    others.
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