Kingdom Animalia
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Multicellular, heterotrophic eukaryotes
Capable of controlled locomotion
Unique tissue: nervous and muscle
35 phyla
> 1 million described species
3 - 30 million estimated number of
species
(See Table 32.1 for a more complete list of
common characteristics)
Animal Origins
• Arose from a colonial flagellated
protistan
– Colonial Theory (Haeckel)
• Coordination and cooperation between
cells
• Common features between animals and
protists
Proterospongia haeckeli
-An extant colonial
choanoflagellate
Note cellular specialization
- flagellated cells
- amoeboid cells
Supporting Evidence for Colonial Theory
• Flagellated sperm cells throughout
Metazoa
• Flagellated body cells among lower
Metazoa
• True eggs and sperm in phytoflagellates
• Phytoflagellates and colonial
organization
Animal Origins
• Despite their morphological diversity,
animals are monophyletic
Supporting Evidence
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Flagellated sperm
Early stages of embryology
Common themes in animal body plans
Despite their morphological diversity,
animals are monophyletic
Key Features in Animal Diversity
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Level of organization
Symmetry
Body plan
Embryological development
Understanding differences and patterns
evident in animal kingdom =
understanding of animal macroevolution
Levels of Organization
• Ancestral form had some specialized cells
and some cooperation between cells
• Subkingdom Parazoa, which includes the
sponges, lack tissues
• Evolution of tissues was next step in
animal evolution
• Compartmentalization into specialized
“regions” was the next step
Organ Systems
With increasing
specialization, eventually
see regionalization
Organs
Tissues
Specialized Cells
Fig. 32.8
Symmetry
How many planes can a body be
divided into along its long axis and
still get mirror images?
Animals that move in one direction have
bilateral symmetry; can be divided into
similar halves on only one plane.
The plane runs from the anterior end to the
posterior end (tail).
A plane at right angle to the midline divides
animals into dorsal and ventral (belly)
surfaces.
Radial symmetry – typically in sessile
animals (all or part of their life cycle)
Bilateral symmetry is associated with
cephalization
Fig. 32.8
Body Plans
Attributes considered for all animals
• Presence or absence of different tissue
types
• Type of symmetry
• Presence or absence of a true body cavity
Body Plans – Bilateral Animals
• All animals based on one of three body
plans
• Different body plans provide different
adaptive advantages
• Apparent trend - increased potential
body size
• Body cavity is area between body wall
and internal organs
Body Plans – Bilateral Animals
• Embryological development of tissues
– Ectoderm
– Mesoderm
– Endoderm
Fig. 32.4c
Acoelomate
Fig. 32.4b
Pseudocoelomate
Fig. 32.4a
Eucoelomate
Acoelomate - cavity
filled with tissue
Pseudocoelomate cavity filled with
liquid
Coelomate - cavity
filled with fluid and
organs supported by
membranes
Fig. 32.8
Embryology and
Developmental
Biology
All animals go
through the same
initial stages of
embryonic development
(see Fig. 32.3)
Protostomes (“mouth first”): the blastopore
develops into the mouth.
Deuterostomes (“mouth second”): the
blastopore develops into the anus; the
mouth develops later.
Embryological Development
• Protostomes
• spiral cleavage
• determinate cleavage
• mesoderm develops
by cell sloughing
• Deuterostomes
• radial cleavage
• indeterminate
cleavage
• mesoderm develops
from tissue folds
Fig. 32.5
Fig. 32.8
Cambrian Explosion
• All animal phyla
except one appeared
in a geological
instant 545 mya
• Some groups
disappeared?
• Why such diversity is
so short a period of
time (20 million
years)?
Molecular View of Animal Phylogeny
• Genomes and Proteomes – Hox genes and
patterning of body axis in vertebrates
• Feature Investigation – Taxonomic
relationship of arthropods
• See Table 32.2
• Will be helpful for Chapters 33-34
• For second Animal Diversity lab
Fig. 32.8