Chapter   16 - ANIMAL CLASSIFICATION, PHYLOGENY, AND ORGANIZATION

CLASSIFICATION of ORGANISMS

• Classification
• systematics
  • an introduction from Dr. Thomas J. Herbert
• taxonomy

A TAXONOMIC HIERARCHY

1. Carolus Linnaeus (1707-1778)
   • hierarchal system: hierarchy of taxonomic ranks [Table 16.1]
     • domain, kingdom, phylum, class, order, family, genus, species
     • see this page on classification by Stephen Abedon for some interesting mnemonics
   • binomial nomenclature
2. more on classification from the University of Minnesota, General Zoology

MAJOR DIVISIONS OF LIFE

Molecular Approaches to Systematics

comparing DNA and RNA sequences

Ribosomal RNA

         evolutionary conservation

Three Domains: Eubacteria, Archaea, Eukarya [fig. 16.2b]

• Procaryotes: The old Kingdom Monera.  Now split into two kingdoms:
  1. Eubacteria from Kimball's Biology Place
  2. Archea from Kimball's Biology Place
• Eucaryotes

Five plus Kingdoms [fig. 16.2a]

Kingdoms		Examples
Monera	Small, simple cell [prokaryote]	Bacteria
Protista	Large, complex cell	Protozoans, Algae
Fungi	Multicellular, specialized, absorb	Molds, Mushrooms
Plantae	Multicellular, specialized, photosynthesize	Mosses - Trees
Animalia	Multicellular, specialized, ingest	Insects - Fishes

ANIMAL SYSTEMATICS

Arranging Organisms into Groups  [fig 16.3]

Using the Evidence of Evolution: Classifying life.  A great overview from Kimball's Biology Pages

Philosophies of Classification

1. Numerical Taxonomy:
2. Evolutionary Taxonomy:
1. phylogenetic tree of vertebrate phylogeny (Fig. 16.4)
3. Phylogenetic Systematics (cladistics)
1. clade: a monophyletic group
2. cladogram (Fig. 16.5)
1. a branching diagram displaying evolutionary relationships
3. To learn more
   • Basic Introduction to Cladistics from the AMNH
   • Journey into the world of phylogenetic systematics from the UCMP
4. Cladistic Terminology
   1. monophyletic:
      • character:
   2. paraphyletic
   3. polyphyletic:
   4. synapomorphy:
   5. clade
5. try this exam from Dr. David Altoff, Vanderbilt University

Evolutionary Relationships and Tree Diagrams

cladogram showing vertebrate phylogeny (Fig. 16.6)

PATTERNS OF ORGANIZATION

ANIMAL SYMMETRY [Table 16.2]

• Illustration1- Illustration2 from UT Biology 301
• asymmetry [fig 16.7]
• Radial versus bilateral symmetry  from the University of Tennessee at Martin
  1. radial symmetry
  2. bilateral symmetry [fig. 16.9]
     1. associated with cephalization--cephalization causes polarity
     2. terminology [Table 16.3] - anterior, posterior, dorsal, ventral, etc.
     3. My parents went to a planet with no bilateral symmetry, and all I got
        was this lousy F-shirt.

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OTHER PATTERNS OF ORGANIZATION

1. Unicellular (Cytoplasmic) Organization
1. "cytoplasmic" grade
   • unicellular, includes most protozoans - all functions within a single cell
2. cellular grade
   • aggregate of cells
     • division of labor e.g. Volvox
     • somatic and reproductive cells
   • perhaps sponges (which are multicellular, but with no germ layers or true tissues, extracellular digestion)
2. Eumetazoa: tissues and organs present
1. germ layers: three embryonic tissues [Table 10.1]
   • tissues derived from the 3 germ layers-figure from Loyola University
     1. ectoderm: outer embryonic layer - skin and nervous tissue
     2. endoderm: inner embryonic layer - lines digestive tract
     3. mesoderm: middle embryonic layer - muscles, bones, circulatory system, organs
2. diploblastic Organization [fig 16.10]: ectoderm and endoderm separated by a noncellular mesoglea
• cell-tissue grade: aggregations of similar cells into definite patterns or layers
• Cnidaria
3. Triploblastic Organization [fig 16.11]:
   • three germ layers are present
   • bilateria: bilateral symmetry (may be lost)

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BODY CAVITIES

acoelomate - left pseudocoelomate - center eucoelomate - right Red = ectoderm Yellow = endoderm Blue = mesoderm Image courtesy of BIODIDAC

 

1. acoelomates:
   1. no body cavity [fig. 16.11a]
   2. body double-walled sac surrounding digestive cavity
   3. single opening to outside
   4. characteristic of flatworms.
2. coelom
   • tube within a tube = body cavity
   • Illustrations from UT Biology 301
   •  advantages
   1. body cavity allows more room for organs in fluid filled cavity with no pressure from muscles
   2. cavity can serve as circulatory system
   3. more efficient and longer digestive system
   4. more room for gonads, gametes, etc.
   5. can function as a hydrostatic skeleton.
1. Pseudocoelomate [fig 16.11b]
   1. body cavity between mesoderm and endoderm (cavity from blastocoel)
   2.  characteristic of roundworms
2. Eucoelomate) [fig. 16.11c]

   1. body cavity completely lined with a thin mesodermal sheet (outer peritoneum and inner serosa

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