Unit 5: The Evolutionary History of Diversity
Extras
Study Guide
Chapter 32
An Introduction to Animal Diversity
Review
Animals are multicellular,
eukaryotes
that ingest their food.
The ancestor of animals
diverged
from those of
about 1.2 billion-800 million years ago, and may have resembled
modern
.
The kingdom diversified about 525 million years ago, 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 of
development.
Protostomes develop their
from the blastopore of the
gastrula
.
Deuterostomes develop their
from the
blastopore
.
Current phylogeny places
as a clade with true
, and divides the Bilateria into three
clades:
,
Lophotrochozoa
, and
Ecdysozoa
.
Review and exercise:
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