Chapter
32
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Cum.
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Appendix
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Art
Unit 5: The Evolutionary History of Diversity
An Introduction to Animal Diversity
Review
Animals are multicellular,
eukaryotes.
The ancestor of animals
diverged
from those of
about 1.2 billion-800 million years ago, and may have resembled
modern
.
The kingdom diversified during the
explosion,
when many animal phyla
appeared.
Animals can be
categorized
by how their cells are organized according to a
plan.
symmetry
is like a flower pot, the body radiates from the center.
symmetry
has a single plane of symmetry.
Most animals
have
that develop from
embryonic
layers of the
.
Diploblastic
animals such as
jellyfish
have
germ layers:
and
.
Triploblastic
animals have
germ layers,
including
a
.
The mesoderm may develop into tissue that line a fluid–filled
space
called a
.
A
is a body
cavity
only partially lined by mesoderm tissues.
Organisms without a body
cavity
are considered
.
The coelomates show two major modes
development.
Protostomes develop their
from blastopore of the
gastrula.
Deuterostomes develop their
from the
blastopore.
Current phylogeny places
as a clade with true
, and divides the
into three clades:
,
Lophotrochozoa,
and
Ecdysozoa.
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Apr 27, 2008
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