Chapter 7 Animal Classification, Phylogeny, and organization

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Chapter 7 Animal Classification, Phylogeny, and
organization

• Ms. K. Cox, Zoology

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Classification page 97

• A.We have identified about 1.4 million species on
  earth three-fourths of these species are
  animals.
• 1. Each species is given a genus and species name
  according to the taxonomic system based on the
  work of Karl von Linnè.
• 2. The binomial (genus and species names)
  nomenclature is universal, and follows rules from
  the International Code of Zoological Nomenclature

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• 3. Closely related species are placed in the same
  genus closely related genera are placed in the
  same family, and so on.
• 4.Taxon is a general term used to represent a
  group of animals at any level of the
  classification scheme.
• B. To decide how closely related one taxon is to
  another, biologists compare the characters or
  traits present across groups.
• 1.The traits used may be morphological- physcial
  features (fur,no fur, brown eyes, green eyes,
  scales)
• or
• 2. molecular- DNA or genes that they have in
  common
• (exact genes they have in common, for example
  Down Syndrome is caused by 2 copies of chromosome
  21)

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• C. Classification of organisms into higher level
  taxa has changed recently.
• 1. A 5 kingdom scheme based on cellular
  properties and mode of nutrition was designed by
  Whittaker in1969 Monera, Protista, Plantae,
  Fungi, and Animalia. Bacteria were placed in the
  kingdom Monera

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Changes

• 2. But new rRNA studies (rRNA changes very
  slowly, so it offers conserved characters for the
  phylogeny of ancient groups) indicate that
  bacteria is a polyphyletic group.
• 3. Bacteria now belong in two groups Archaea and
  Eubacteria. These two groups replace the previous
  Kingdom Monera.

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• 4. Living things are commonyly grouped into a 3
  domain, 6 kingdom system.
• (This is new) Domains Archaea, Eubacteria,
  Eukarya

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6 Kingdoms
5 Kingdoms
Domains Archaea, Eubacteria, Eukarya
1. Monera 2. Protista 3. Plantae 4. Fungi 5.
Animalia

• 1. Plantae
• 2. Animalia
• 3. Protista
• 4. Fungi
• 5. Archaebacteria
• 6. Eubacteria

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• 5. The new taxonomy system.
• Domain-3 groups
• Kingdom-6 groups
• Phylum
• Class
• Order
• Family
• Genus
• Species

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• D. Systematics is the arrangement of organisms
  based on evolutionary relationships indicated by
  shared characters.
• 1. The groups formed in modern systematics are
  designed to be monophyletic polyphyletic groups
  are avoided.
• 2. Monophyletic groups include all organisms that
  have arisen from a single ancestral taxon
• 3. polyphyletic groups are artificial groupings
  whose members have arisen from separate
  ancestors.

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• E. There are 3 main schools of systematics that
  differ in their goals and approaches
• 1. Evolutionary systematics is a traditional
  approach which looks for similar characters and
  homologies to group organisms into taxa.
• 2. Numerical taxonomy is based on a quantitative
  analysis of characters to determine taxa and does
  not attempt to distinguish between shared states
  due to common ancestry and shared states due to
  convergence.
• 3. Phylogenetic systematics (cladists) analyzes
  both symplesiomorphies (shared ancestral
  characters) and synapomorphies (shared derived
  characters) to determine cladograms.

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Invertebrate or Vertebrate
What are Invertebrates? Invertebrates are a broad
collection of animal groups (they do not belong
to a single subphylum like the vertebrates) all
of which lack a backbone. Some (not all) of the
animal groups that are invertebrates
include -Sponges (Phylum Porifera) -Jellyfish,
hydras, sea anemones, corals (Phylum
Cnidaria) -Comb jellies (Phylum
Ctenophora) -Flatworms (Phylum Platyhelminthes) -M
olluscs (Phylum Mollusca) -Arthropods (Phylum
Arthropoda) -Segmented worms (Phylum
Annelida) -Echinoderms (Phylum Echinodermata)
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Vertebrate

• bilateral symmetry
• body segmentation
• endoskeleton (bony or cartilaginous) (they have a
  backbone)
• pharyngeal pouches (present during some stage of
  development)
• complete digestive system
• ventral heart
• closed blood system
• tail (at some stage of development)

The animal classes that are vertebrates
include Jawless fish (Class Agnatha) Armored
fish (Class Placodermi) - extinct Cartilaginous
fish (Class Chondrichthyes) Bony fish (Class
Osteichthyes) Amphibians (Class
Amphibia) Reptiles (Class Reptilia) Birds (Class
Aves) Mammals (Class Mammalia)
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F. Symmetry

• 1. The basic body plans of animals may be
  analyzed to illustrate evolutionary trends. The
  first consideration is body symmetry
• Animals may be asymmetrical, as in many protists
  and sponges such animals lack complex sensory
  and locomotory functions.

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2. 3 Types of Symmetry

• A. asymmetry
• B. bilateral symmetry
• C. radial symmetry

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3. asymmetry

• The arrangement of body parts without a central
  axis or point.
• (such animals lack complex sensory and locomotory
  functions)

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Illustration of difference between symmetrical
and asymmetrical.
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Tube Sponge(Callyspongia vaginalis)
The Tube Sponge is one of the most common
varieties of sea sponge to be found on the reef.
It is distinguished by its long tube-shaped
growths, and ranges in color from purple to blue,
gray, and gray-green. Filtered water is ejected
through the large openings on the ends. This is
one of the few reef invertebrates that is blue in
color.
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Sponges
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4. bilateral symmetry

• The arrangement of body parts such that a single
  plane passing between the upper and lower
  surfaces and divides the animal into a right and
  left mirror image.(most things fall into this
  category)

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Hippopotamus
Hippos are herbivores and their diet consists
mainly of grass and some water plants.  Hippos do
most of their eating during the night, while
during the day hippos spend most of their time
basking in the sun on a sandbar or floating
lazily in the water with just their ears, eyes,
and nostrils, and perhaps their back and top of
the head, exposed.  The name hippopotamus comes
from the Greek "hippos," meaning horse.  Hippos
were once called "river horses," even though they
are more closely related to pigs than horses. Big
male hippos can tip the scales at over three
tons.
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The Common Dog
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5. radial symmetry

• The arrangement of body parts such that any plane
  passing through the oral-aboral axis divided the
  animal into mirror images.

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Cnidarian
Cnidarians are radially symmetrical. This means
that their gastrovascular cavity, tentacles, and
mouth are aligned such that if you were to draw
an imaginary line through the center of their
body, from the top of their tentacles through the
base of their body, you could then turn the
animal about that axis and it would look roughly
the same at each angle in the turn. Another way
to look at this is that cnidarians are
cylindrical and have a top and bottom but no left
or right side.
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Echinodermata (e.x. starfish)
Sea stars or starfish are marine invertebrates
belonging to phylum Echinodermata, class
Asteroidea. The names sea star and starfish are
also used for the closely related brittle stars,
which make up the class Ophiuroidea. They exhibit
a superficially radial symmetry, typically with
five or more "arms" which radiate from an
indistinct disk (pentaradial symmetry). In fact,
their evolutionary ancestors are believed to have
had bilateral symmetry, and sea stars do have
some remnant of this body structure.
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G. Unicellular Level of
Organization page 105

• 1. The second consideration is the level of
  cellular organization
• A. The single celled organisms, or those formed
  from aggregates of single cells, exhibit the
  cytoplasmic level of organization these cells
  have very little interdependence and do not form
  tissues.

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• Diploblastic Organization.
• These organisms, like the cnidarians, have two
  tissues layers formed from the embryonic ectoderm
  and endoderm. The cell layers are
  interdependent.
• Triploblastic Organization.
• These organisms have 3 tissue layers derived from
  the embryonic ectoderm, mesoderm, and endoderm.

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Body Cavity

• 1.The third consideration is the presence of a
  body cavity (not the gut cavity, but a cavity
  external to the gut)
• 2.The body cavity Functions
• A. provide more room for organ development
• B. Provide more surface area for diffusion
• C. provide an area for storage
• D. often act as hydrostatic skeletons
• E. provide a vehicle for eliminating wastes and
  for reproduction
• F. Facilitate increased body size.

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Possibilities in the Triploblastic Organization

• 1. Triploblastic Acoelomate Pattern
• A. see page 106, Figure 7.11 A. Draw this example
  in your notes.
• B. Description thin ectoderm, thick mesoderm,
  and thin endoderm, with small opening in the
  middle called a gut. The mesoderm touches the
  endoderm.
• C. Examples of flat worms, tapeworm. (chapter 10)

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-Continued- Possibilities in the Triploblastic
Organization

• 2. Triploblastic Pseudocoelomate Pattern
• A. see page 106, Figure 7.11 B. Draw this example
  in your notes.
• B. Description thin ectoderm, thin mesoderm,
  thin endoderm, as an extra space between the
  Mesoderm and the Endoderm called the
  Pseudocoelom.
• C. Examples roundworm, filarial worm- causes
  elephantiasis see page 174 (chapter 11)

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Continued- Possibilities in the
Triploblastic Organization

• 3. Triploblastic Coelomate Pattern
• A. See page 106, Figure 7.11 C. Draw this example
  in your notes.
• B. Description Thin Ectoderm, thicker mesoderm
  that has space to the left and the right. The
  mesoderm butts up directly to the Endoderm. In
  the center there is a small opening.
• C. Example Nemertea (ribbon worms)
• ,

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Higher Animal Taxonomy

• 1. Animalia are considered monophyletic. Due to
  cellular organization.
• 2. The Cambrian Explosion- about 0.6 billion
  years ago an evolutionary explosion occurred
  which resulted in the origin of all modern phyla.
  (phyla many groups)
• 3. Three main groups or braches in the animal
  kingdom.
• A. Mesozoa
• B. Parazoa (sponges)

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Continued

• C. Eumetazoa- divided into further groups based
  on body symmetry.
• 1. Radiata
• 2. Bilateria
• A. Protostomia (Platyhelminthes, Nematoda,
  Mollusca, Annelida, Arthropoda)
• 1. Trochophore larva see page 108 figure 7.12 D.
  draw an example in your notes.
• B. Deuterostomia-(Echinodermata, hemichordata,
  chordata)
• 1. Dipleurula larva see page 108 figure 7.12 H.
  Draw an example in your notes.

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Continued

• 4. Scientists use Comparative embryology.
  (Definition the observation that embryological
  events may be similar because of shared
  ancestry.)