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Kingdom Animalia
Ch. 32
Lecture Objectives
Animal Characteristics
2. Embryology
3. Protostomes vs. Deuterostome
1.
The history of animals
 Common ancestor  675 - 875 mya
 Resembled modern Choanoflagellates
Individual
choanoflagellate
Choanoflagellates
OTHER
EUKARYOTES
Sponges
Animals
Collar cell
(choanocyte)
Other animals
Fig. 32.3
Time Period
Characteristics
Paleozoic Era (542-251mya)
Cambrian Explosion – earliest fossils
- new predator prey relationships
- rise in atmospheric oxygen
- HOX gene complex
mass extinction 460
Vertebrates on land 360mya
Mesozoic Era (251-65.5mya)
- Coral Reefs
- Dinosaurs were dominant
- See first mammals
Cenozoic Era (65.5mya – present)
- Followed by mass extinctions
(large, non-flying dinos & marine
reptiles)
- Modern mammals & insects diversified
Cambrian Seascape
Fig. 32.7
Animal Characteristics
1. Eukaryotic & Multicellular
2. Hetertrophic  ingestion
3. Lack cell walls
• Intercellular junctions
i. Tight Junctions
ii. Gap Junctions
iii. Desmosomes
Intercellular Junctions
Animal characteristics con’t.
4. Nervous & muscle tissue
5. Sexual reproduction
 Oogamous
 Diploid Dominant Life cycle
i. cleavage
ii. blastula
iii. gastrulation
iv. gastrula
v. larva & metamorphosis
Blastocoel
Cleavage
Endoderm
Cleavage Blastula
Ectoderm
Zygote
Eight-cell stage
Gastrulation
Blastocoel
Archenteron
Gastrula
Blastopore
Cross section
of blastula
Fig. 32.2
Animal characteristics con’t.
6. Hox genes that regulate the development of body form
Animal characteristics con’t.
7. Temperature regulation
 endothermic (homeothermic)
 ectothermic (poikilothermic)
Animal characteristics con’t.
8. Symmetry
Asymmetrical
• Symmetrical
i. radial: oral (top) side & aboral (bottom)
•
ii. Bilateral: L & R sides
-dorsal (top) & ventral (bottom)
- anterior (head) & posterior (tail)
 Cephalization: development of
a head
(a) Radial symmetry
(b) Bilateral symmetry
Figure 32.8
Animal Characteristics con’t.
9. Tissue Layers
• Diploblastic – animals w/ radial symmetry
• Triploblastic – animals w/ bilateral symmetry
Diploblasitc
Ectoderm & Endoderm
(radial symmetry)
Triploblastic
Eco, Endo + Mesoderm
(bilateral symmetry)
Animal characteristics con’t.
10. body cavity (in triploblastic animals only!)
 Absorbs shock, hydrostatic skeleton, allows organs to
shift, muscle growth independent from body wall
 Coelom = body cavity derived from mesoderm
 Three variations on coeloms:
i. acoelomate
ii. pseudocoelomate
iii. coelomate
Coelom
Digestive tract
(from endoderm)
Body covering
(from ectoderm)
Tissue layer
lining coelom
and suspending
internal organs
(from mesoderm)
(a) Coelomate
Body covering
(from ectoderm)
Pseudocoelom
Muscle layer
(from
mesoderm)
Digestive tract
(from endoderm)
(b) Pseudocoelomate
Body covering
(from ectoderm)
Tissuefilled region
(from
mesoderm)
Wall of digestive cavity
(from endoderm)
(c) Acoelomate
Fig. 32.9
Animal characteristics con’t.
11. Embryological Development
 Categorized as a protostome or deuterostome
(based on embryological differences)
Protostome development
(examples: molluscs,
annelids)
Deuterostome development
(examples: echinoderm,
chordates)
Eight-cell stage
Eight-cell stage
Spiral and determinate
(a) Cleavage
Radial and indeterminate
(b) Coelom formation
Key
Coelom
Ectoderm
Mesoderm
Endoderm
Archenteron
Coelom
Mesoderm
Blastopore
Blastopore
Solid masses of mesoderm
split and form coelom.
Mesoderm
Folds of archenteron
form coelom.
Anus
Mouth
(c) Fate of the blastopore
Digestive tube
Mouth
Mouth develops from blastopore.
Anus
Anus develops from blastopore.
Fig. 32.10