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What are the three domains of life?
Animal diversity 1 - Evolution
of the animal body plan
Bacteria
Archaea
Eukarya
What are the kingdoms?
Bacteria
Arachaea
protists
Plantae
Fungi
Animalia
Key concepts for today
• Definition of an animal
• Major phyla, and their relatedness
(where they are on a tree)
• Major stages in evolution of animal
body plan and where they occurred
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2
What features together define a
member of the Kingdom Animalia?
Phylogenies of the deep roots of life
are controversial
(not to memorize:) 2005 revision of Eukarya
kingdoms: instead of three, six: four protist
kingdoms, “Opisthokonta” (fungi + animals)
and “Archaeplastida” (plants)
Among protist systematists, even this
arrangement is controversial. “I’ve seen
people throw things at each other” one of the
authors says.
Your text book has a different arrangement of
animal phyla. The one we will focus on today
is used in Lab 4 - learn this one rather than the
one in the book.
Why can’t we reconstruct these ancient
divisions with certainty?
Multicellularity
In what Kingdom do animal-like single
celled creatures belong?
Are all protists unicellular?
What else is common to all animals?
Heterotrophic life style
Heterotrophic? Autotrophic?
3
2a
What features together define a
member of the Kingdom Animalia?
Extracellular matrix (ECM)
Multicellularity
Heterotrophic life style
And?
Extracellular matrix (ECM)
- extra (outside) cellular (cells) matrix
(“stuff” or more precisely “substance
within which something originates,
develops, or is contained”)
Made up of proteins and
glycoproteins
Give animal cells and animals
structure
Hard stuff in bone, cartilage, forms
soft barriers and filters around
cells, e.g. gut linings
Same as a cell wall?
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What other traits do you associate
with animals?
Animal quiz: Are each of these
animals? If so, what phylum?
Why do they have them?
Do all animals have them?
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Animal quiz: Are each of these
animals? If so, what phylum?
Animal quiz: Are each of these
animals? If so, what phylum?
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Animal quiz: Are each of these
animals? If so, what phylum?
Animal quiz: Are these animals? If
so, what phylum?
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Animal quiz: Are each of these
animals? If so, what phylum?
Animal quiz: Are these animals? If
so, what phylum?
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Today - evolution of the animal
body plan
One hypothesis for evolution of
major animal phyla
p. 52 of your lab manual
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One hypothesis for evolution of
major animal phyla
One hypothesis for evolution of
major animal phyla
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CN
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PROTISTS
PROTISTS
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One hypothesis for evolution of
major animal phyla
One hypothesis for evolution of
major animal phyla
NEMATODA
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PROTISTS
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PROTISTS
One hypothesis for evolution of
major animal phyla
One hypothesis for evolution of
major animal phyla
PROTOSTOMES
PROTOSTOMES
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PROTISTS
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PROTISTA
One hypothesis for evolution of
major animal phyla
What key features differentiate animals
from protists?
PROTOSTOMES
PROTOSTOMES
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DEUTEROSTOMES
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PROTISTS
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Simple animals - the Porifera
(Sponges)
What key features differentiate animals
from protists?
PROTOSTOMES
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NEMATODA
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MULTICELLULARITY, ECM
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PROTISTA
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Simple animals - the Porifera
(Sponges)
Pore cells
Where do our sponges get their
name?
H 2O
Several cell
types in ECM like fruit in jello
H 2O
Fig. 32.4
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Simple animals - the Porifera
(Sponges)
Cells that move
water and absorb
food
“Choanocytes”
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The choanocytes
Choanoflagellates colonial
protists with similar cell
types
Regulate H20 movement with
flagellum
Collect food particles at flagellum
base, absorb directly into the cell
Since 1880s
similarity noted
Recently (2001):
signalling gene in
common
from text
choanocytes
Simple animals with cellular
organization - the Porifera (sponges)
Protist ancestors of
animals?
Sponge
choanocyte
Tube
organization
choanoflagellate 28
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Party tricks
with sponges…
So, sponges have what kind of
digestion?
Intracellular digestion - digest food
within individual cells
What does this mean about the size
of the food they can eat?
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Simple animals with cellular
organization - the Porifera (sponges)
Cells from a sponge can be
completely disassociated, strained
through a filter...
And they will re-form into a sponge
again in a few weeks
What does this mean about the way
they are organized?
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One last thing about sponges…
If a tissue is a group of similar
cells organized into a functional
unit, do sponges have tissues?
They’re
asymmetrical
-tubes grow into
other tubes - can’t
bisect them and
make two equal
halves
Sponges have cellular
organization
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The Cnidaria
The Cnidaria
Two cell layers
Tentacles around
a mouth that
closes
Is it symmetrical?
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Cross section of a
sea anenome
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Radial symmetry
Evolution of symmetry
Asymmetrical
Radial
symmetry
Bilateral
symmetry
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A plane through the center in any
direction will bisect the organism into
equal halves
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Advantages of bilateral
symmetry?
Bilateral symmetry
A front and a back as
well as a top and a
bottom
Allows concentration of
sensory apparatus on
one side (front) of one
end (top!)
Only a single plane will bisect the
organism into equal halves
Why is this a good thing
for mobile animals?
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The innovations of the Cnidaria
The innovations of the Cnidaria
Cells work together in
layers: tissue
organization
Cnidarian dining
What kind of
digestion?
If we disassociated the
cells of a cnidarian and
left them in a tank ?
Cross section of a
sea anenome
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Cross section of a
sea anenome
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The innovations of the Cnidaria
The innovations of the Cnidaria
Do cnidarians have
a gut?
Where do their
waste products
go?
Mouth but no anus
What are the
problems with
this?
Extracellular
digestion
What does this mean
about the size of
food they can
consume?
Cross section of a
sea anenome
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The innovations of the Cnidaria
Cross section of a
sea anenome
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Evolution of the coelom
What’s a coelom?
Is it the same thing as a gut?
Where is the coelom on humans?
Review:
Radial symmetry
Extracellular digestion
Mouth but no anus - in Nematoda have
both
And…
No coelom
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Evolution of the body cavity - the
coelom
In humans
divided
into two thoracic
and
abdominal
cavities
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We will distinguish between 3 types of
animals
Acoelomate (‘a’-without) - e.g.
Sponges, Cnidaria, Flatworms
(Platyhelminthes)
In
earthworms,
coelom
in each
segment
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We will distinguish between 3 types of
animals
We will distinguish between 3 types of
animals
Acoelomate (‘a’-without) - e.g.
Sponges, Cnidaria, Flatworms
(Platyhelminthes)
Pseudocoelomate - e.g. Nematoda
Ectoderm
Ectoderm
Mesoderm solid
Mesoderm
layer
Endoderm
Endoderm
Gut cavity
Cavity
Gut cavity
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We will distinguish between 3 types of
animals
Which is acoelomate? Coelomate?
Pseudocoelomate?
Coelomate - e.g. all protostomes and
deuterostomes Mesoderm
surrounds cavity (coelom) and gut
Ectoderm
Mesoderm
layers (two!)
Cavity
Endoderm
Gut cavity 50
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Why was evolution of a coelom
important in animal evolution?
What differentiates these groups?
3 reasons (not all relevant for all groups)
1) Coelom can function as a simple
circulatory system
2) Fluid in a body cavity can help make
the body rigid - a hydrostatic skeleton
3) Organs can function without being
deformed by surrounding muscles
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Allows the development of a longer gut, can be
coiled, etc.
How long is the combined human small and
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large intestines?
DEUTEROSTOMES
PROTISTA
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In Protostomes (‘proto’-first, ‘stome’-mouth)
- the blastopore gives rise to the mouth
Groups can be distinguished by
early embryonic development
Blastopore
Blastula
Blastopore
Gastrula
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In Deuterostomes (‘deutero’- 2nd, ‘stome’mouth) - the blastopore gives rise to the
anus
Mapping body plan characters on
the tree
PROTOSTOMES
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Blastopore
DEUTEROSTOMES
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EXTRACELLULAR
DIGESTION?
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Mapping body plan characters on the tree
Mapping body plan characters on
the tree
PROTOSTOMES
PROTOSTOMES
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EXTRACELLULAR DIGESTION
MULTICELLULARITY
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TISSUES
EXTRACELLULAR DIGESTION
PROTISTA MULTICELLULARITY
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DEUTEROSTOMES
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PROTISTA
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PROTISTA MULTICELLULARITY, ECM
RADIAL
SYMMETRY?
BILATERAL
SYMMETRY?
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Mapping body plan characters on
the tree
Mapping body plan characters on
the tree
PROTOSTOMES
PROTOSTOMES
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PROTOSTOMES
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MOUTH AND ANUS
BILATERAL SYMMETRY
TISSUES
EXTRACELLULAR DIGESTION
PROTISTA MULTICELLULARITY
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BILATERAL SYMMETRY
TISSUES
EXTRACELLULAR DIGESTION
PROTISTA MULTICELLULARITY
Mapping body plan characters on
the tree
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M
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BILATERAL SYMMETRY
TISSUES
EXTRACELLULAR DIGESTION
PROTISTA MULTICELLULARITY
TYH
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MOUTH AND
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DEUTEROSTOMES
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TRUE
COELOM?
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