1. INTRO TO ANIMAL DIVERSITY
Common Characteristics
Development
History
Body Plan
Diversity and Phylogeny

2. Common Characteristics of Animals: multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers
Cell Structure
Multicellular, Eukaryotic, no cell walls
Support by extracellular proteins (e.g., collagen, cadherins)
Most have Muscle & Nervous tissues
Nutritional Mode:
Heterotrophs w/ internal digestion
REPRODUCTION/LIFE-CYCLE
Mostly sexual reproduction & diploid dominant
DEVELOPEMENT
Zygote  cleavage  gastrulation & tissue (germ layer) formation
Regulated by homeoboxes (e.g., Hox genes

3. Eight-cell stage Cross section of blastula Cross section of gastrula
Figure
Zygote
Cleavage
Eight-cell
stage
Cleavage
Blastocoel
Cross section
of blastula
Blastula
Figure Early embryonic development in animals (step 3)
Gastrulation
Cross section
of gastrula
Blastocoel
Endoderm
Ectoderm
Blastopore
Archenteron

4. Larval Stages Most animals have at least one larval stage
Morphologically distinct from parent; different food source (ecological role)
Larvae juvenile
A juvenile resembles an adult, but is not yet sexually mature
metamorphosis

5. Evolutionary History of Animals: 770-700 m. y. of evolultion; 1
Evolutionary History of Animals: m.y. of evolultion; 1.3+ million species
Fossil evidence of animals 770 m.y.o
Closest living relative to animals are Choanoflagellates
Cadherin protein domain similarities
Cell attachement and cell signalling gene similarity + morphological similarity w/ sponges
CCD domain that is unique to animals
560 m.y.a.: macroscopic animals & predator-prey relationships
m.y.a: Cambrian explosion
large animals, bilateral animals, exoskeletons, mineralized endoskeletons inc. arthropods, chordates, and echniderms
~450 m.y.a .: first terrestrial animals appear (arthropods)
~365 m.y.a.: first terrestrial vertebrates appear giving rise to reptiles and amphibians
~ m.y.a.: first mammals appear (coincides with angiosperm development)
65m.ya.- present:
Large marine reptiles and non-flying dinosaurs experienced massive extinctions, medium and large mammals came to dominate terrestrial ecosystems

6. Individual choanoflagellate Choano- flagellates OTHER EUKARYOTES
Figure 32.3
Individual
choanoflagellate
Closest animal relative
Choano-
flagellates
OTHER
EUKARYOTES
Sponges
Figure 32.3 Three lines of evidence that choanoflagellates are closely related to animals
Animals
Collar cell
(choanocyte)
Other
animals

7. Choano- flagellate Hydra “CCD” domain (only found in animals) Fruit
Figure 32.4
Choano-
flagellate
Hydra
“CCD” domain (only
found in animals)
Fruit
fly
By recombination of choanoflagellate domain + unique domain
Mouse
Figure 32.4 Cadherin proteins in choanoflagellates and animals

8. Animals can be characterized by “body plans”
Body plan = symmetry + tissue organization + body cavity + development
Asymmetry
Radial symmetry
Bilateral symmetry
Germ Layers:
Endoderm?
Ectoderm?
Mesoderm?
aceolomate
psuedocoelomate
coelomate
Protostome
dueterostome

9. Bilaterally symmetric
Symmetry
Bilaterally symmetric
Radially symmetric
asymmetric

10. (a) Radial symmetry (b) Bilateral symmetry Figure 32.8
Figure 32.8 Body symmetry
(b)
Bilateral symmetry

11. Video: Sea Urchin Embryonic Development (Time Lapse)

12. Coelomates & pseudocoelomates = grades NOT clades
Body Cavity = Coelum
(a)
Coelomate
(b)
Psuedocoelomate
Coelom
Body covering
(from ectoderm)
Body covering
(from ectoderm)
Tissue layer
lining coelom
and suspending
internal organs
(from mesoderm)
Muscle layer
(from
mesoderm)
Pseudo-
coelom
Digestive tract
(from endoderm)
Digestive tract
(from endoderm)
(c)
Acoelomate
Body covering
(from ectoderm)
Key
Ectoderm
Figure 32.9 Body cavities of triploblastic animals
Tissue-
filled region
(from
mesoderm)
Mesoderm
Endoderm
Wall of digestive cavity
(from endoderm)
Coelomates & pseudocoelomates = grades NOT clades

13. (a) Coelomate Coelom Body covering (from ectoderm) Tissue layer
Figure 32.9a
(a)
Coelomate
Coelom
Body covering
(from ectoderm)
Tissue layer
lining coelom
and suspending
internal organs
(from mesoderm)
Digestive tract
(from endoderm)
Figure 32.9a Body cavities of triploblastic animals (part 1: coelomate)
Key
Ectoderm
Mesoderm
Endoderm

14. (b) Pseudocoelomate Body covering (from ectoderm) Muscle layer (from
Figure 32.9b
(b)
Pseudocoelomate
Body covering
(from ectoderm)
Muscle layer
(from
mesoderm)
Pseudo-
coelom
Digestive tract
(from endoderm)
Figure 32.9b Body cavities of triploblastic animals (part 2: pseudocoelomate)
Key
Ectoderm
Mesoderm
Endoderm

15. Wall of digestive cavity (from endoderm)
Figure 32.9c
(c)
Acoelomate
Body covering
(from ectoderm)
Tissue-
filled region
(from
mesoderm)
Wall of digestive cavity
(from endoderm)
Figure 32.9c Body cavities of triploblastic animals (part 3: acoelomate)
Key
Ectoderm
Mesoderm
Endoderm

16. Protostome development (examples: molluscs, annelids)
Figure 32.10
Protostome development
(examples: molluscs,
annelids)
Deuterostome development
(examples: echinoderms,
chordates)
(a)
Cleavage
Eight-cell stage
Eight-cell stage
Spiral and determinate
Radial and indeterminate
(b)
Coelom
formation
Coelom
Archenteron
Coelom
Mesoderm
Blastopore
Blastopore
Mesoderm
Solid masses of mesoderm
split and form coelom.
Folds of archenteron
form coelom.
Figure A comparison of protostome and deuterostome development
(c)
Fate of the
blastopore
Anus
Mouth
Digestive tube
Key
Ectoderm
Mesoderm
Mouth
Anus
Endoderm
Mouth develops from blastopore.
Anus develops from blastopore.

17. Protostome development (examples: molluscs, annelids)
Figure 32.10a
Protostome development
(examples: molluscs,
annelids)
Deuterostome development
(examples: echinoderms,
chordates)
(a)
Eight-cell stage
Eight-cell stage
Cleavage
Figure 32.10a A comparison of protostome and deuterostome development (part 1: cleavage)
Spiral and determinate
Radial and indeterminate

18. Protostome development (examples: molluscs, annelids)
Figure 32.10b
Protostome development
(examples: molluscs,
annelids)
Deuterostome development
(examples: echinoderms,
chordates)
(b)
Coelom
formation
Coelom
Archenteron
Coelom
Key
Mesoderm
Blastopore
Blastopore
Mesoderm
Ectoderm
Figure 32.10b A comparison of protostome and deuterostome development (part 2: coelom formation)
Mesoderm
Solid masses of mesoderm
split and form coelom.
Folds of archenteron
form coelom.
Endoderm

19. Protostome development (examples: molluscs, annelids)
Figure 32.10c
Protostome development
(examples: molluscs,
annelids)
Deuterostome development
(examples: echinoderms,
chordates)
(c)
Fate of the
blastopore
Anus
Mouth
Digestive tube
Key
Ectoderm
Mouth
Anus
Figure 32.10c A comparison of protostome and deuterostome development (part 3: fate of the blastopore)
Mesoderm
Mouth develops
from blastopore.
Anus develops
from blastopore.
Endoderm

20. Cleavage In protostome development, cleavage is spiral and determinate
In deuterostome development, cleavage is radial and indeterminate
With indeterminate cleavage, each cell in the early stages of cleavage retains the capacity to develop into a complete embryo
Indeterminate cleavage makes possible identical twins, and embryonic stem cells

21. Coelom Formation
In protostome development, the splitting of solid masses of mesoderm forms the coelom
In deuterostome development, the mesoderm buds from the wall of the archenteron to form the coelom

22. Fate of the Blastopore
The blastopore forms during gastrulation and connects the archenteron to the exterior of the gastrula
In protostome development, the blastopore becomes the mouth
In deuterostome development, the blastopore becomes the anus

23. 36+ animal phyla: based on morphological, molecular, and fossil data
Five important points about the relationships among living animals are reflected in their phylogeny
1. All animals share a common ancestor
2. Sponges are basal animals
3. Eumetazoa (“true animals”) is a clade of animals with true tissues
4. Most animal phyla belong to the clade Bilateria
5. There are three major clades of bilaterian animals, all of which are invertebrates, animals that lack a backbone, except Chordata, which are classified as vertebrates because they have a backbone

24. invertebrates protostomes Porifera Metazoa Ctenophora ANCESTRAL
Figure 32.11
Porifera
ANCESTRAL
PROTIST
Ctenophora
Metazoa
Cnidaria
Eumetazoa
Acoela
Single common animal ancestor
Hemichordata
Echinodermata
True Tissues
Deuterostomia
Bilateria
Chordata
Bilateral &
3 germ layers
Platyhelminthes
invertebrates
Rotifera
Only phylum
containing vertebrates
Ectoprocta
Figure A phylogeny of living animals
Lophotrochozoa
Brachiopoda
protostomes
Mollusca
Annelida
Nematoda
Ecdysozoa
Arthropoda