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CHAPTER 32
AN INTRODUCTION
TO ANIMAL DIVERSITY
Prepared by
Brenda Leady, University of Toledo
Copyright (c) The McGraw-Hill
Companies, Inc. Permission required
for reproduction or display.
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Characteristics


Most have ______, __________, capacity
to _______ at some point in the life cycle
 Ability to reproduce ____________
 ____________ sensory structures and
nervous system
 Cells exist in…


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Traditional classifications
Most biologists agree kingdom is
______________
 Animal ___________ are very similar
 Most likely ancestor a ____________
___________ similar to ______________ About ___ recognized animal _____

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Traditional classification based on body plans

4 main morphological and developmental
features used
1.
2.
3.
4.
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1.
Tissues

2.
Metazoa divided into ________ (no specialized
tissues or organs) and ___________ (more than
one type of tissue and organs)
Symmetry

Eumetazoa are …

Bilateral animals have __________ and dorsal and
ventral ends
Radial animals have…

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
Number of cell layers
 Radial
animals have …
 Bilateral animals have …
 Cell
layers develop during _____________
 Inner layer –
 Outer layer –
 Mesoderm 
Forms ________ and _____________________
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3.
Body cavity

True coelom –

Pseudocoelom –

Acoelomates –

Fluid-filled body cavity can protect internal
organs or be used as __________________
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4.
Embryonic development

Cleavage in the zygote can be…

Protostome
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Blastopore becomes __________
__________________ coelom development
Deuterostome
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
Blastopore becomes _______
______________ coleom development
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Other methods of classification
Possession of _________________
 Development of ________________
 Presence or absence of _________
(segmentation)

 Traced
to changes in…
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Changes in Hox Gene Expression Control
Body Segment Specialization
Based on relatively simple changes in the
expression patterns of ____________
 Hox genes designated _____
 Shifts in patterns of gene expression in the
embryo along the _____________________
govern transition from one type of vertebra to
another and short or long necks

Molecular views of animal diversity
Now using new molecular techniques to
classify animals by comparing similarities
in the ____ and the ______________ of
animals, especially sequences of
nucleotides in the gene that encodes RNA
of the small ribosomal subunit (SSU rRNA)
 Advantage …

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Aguinaldo and Colleagues Used 18S rDNA to
Analyze the Taxonomic Relationships of Arthropods
to Other Taxa




Sequenced the complete gene encoding SSU
rRNA
Relationships among 50 species determined
Data indicated existence of monophyletic cladethe …
Ramifications of studies involving Drosophila
melanogaster and Caenorhabditis elegans
Similarities between traditional and
molecular phylogeny
1.
2.
3.
4.
The clade called ______________________, meaning
all animals came from a single common ancestor.
At the earliest stages of evolution, molecular phylogeny
supports the traditional view of the split between
__________________________________.
There is also agreement about an early split between
__________________, with most animal phyla
belonging to the Bilateria.
Molecular phylogeny also agrees that the echinoderms
and chordates belong to a clade called the
____________________.
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2 key differences between
traditional and molecular phylogeny
1.
Division of protostomes into 2 clades


2.
Traditionally split into _______________ and
______________ based on embryonic development
Deuterostomes still separate but protostomes
divided into _____________ and _____________
Presence or absence of a body cavity

Traditionally split into…

Molecular evidence indicates presence or
absence…
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