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Chapter 32 An Introduction to Animal Diversity1. What is an animal?
- Multicellular, heterotrophic eukaryote – ingestion- Structural support from structural proteins – NOT cell walls- Nervous tissue & muscle tissue for impulse conduction & movement- Sexual reproduction with motile sperm swimming to non-motile egg
2. How did animals evolve?- Current animal development
Figure 32.2 Early embryonic development in animals (layer 1)
Zygote
Cleavage
Eight-cell stage
Cleavage – cell division w/out cytokinesis- More cells but same total volume – no cell growth
Figure 32.2 Early embryonic development in animals (layer 2)
Zygote
Cleavage
Eight-cell stage
Cleavage
Blastula Cross section of blastula
Blastocoel
Blastula – hollow ball of cells-coel – opening or cavity
Figure 32.2 Early embryonic development in animals (layer 3)
Zygote
Cleavage
Eight-cell stage
Cleavage
Blastula Cross section of blastula
Blastocoel
Blastocoel
Gastrula Gastrulation
Endoderm
Ectoderm
Blastopore
Ectoderm – outside layerEndoderm – inside layer
Gastrulation – movement of cells to form 2 layersBlastopore – opening where cells move into
Chapter 32 An Introduction to Animal Diversity1. What is an animal?
- Multicellular, heterotrophic eukaryote – ingestion- Structural support from structural proteins – NOT cell walls- Nervous tissue & muscle tissue for impulse conduction & movement- Sexual reproduction with motile sperm swimming to non-motile egg
2. How did animals evolve?- Current animal development- Current hypothesis
Figure 32.4 One hypothesis for the origin of animals from a flagellated protist
Colonial protist,an aggregate ofidentical cells
Hollow sphereof unspecialized cells (shown in cross section)
Beginning of cell specialization
Infolding Gastrula-like “protoanimal”
Somatic cells Digestivecavity
Reproductive cells
Radial
Bilateral
Chapter 32 An Introduction to Animal Diversity1. What is an animal?2. How did animals evolve?3. How are animals grouped & characterized?
- Body plans- Symmetry
- None (sponge) - Radial
- multiple central axis “cuts” provide mirror images- Only have top & bottom
- Bilateral- Only 1 central axis “cut” provides a mirror image- Has top, bottom, left & right
H-W Lab-All 6 sections-Personal Acct
-Data for all 3 Cases including NEW p & q-Discussion questions for all 3 Cases-6 practice problems at the end-Not Exercise 8A or Case IV
Protist ID Lab-All 6 sections-Pre-lab from in-class notes-Personal acct
-include characteristics that you keyed out-name of organism-drawing of organism
Chapter 32 An Introduction to Animal Diversity1. What is an animal?2. How did animals evolve?3. How are animals grouped & characterized?
- Body plans- Symmetry & TISSUES
- None (sponge) - Radial
- multiple central axis “cuts” provide mirror images- Only have top & bottom- Diploblastic – 2 cell layers
- Ectoderm - Endoderm
- Bilateral- Only 1 central axis cut provides a mirror image- Has top, bottom, left & right- Triploblastic – 3 cell layers
- Ectoderm & endoderm- Mesoderm – in between ecto- & endoderm
- Cephalization – movement of sensory equipment towards the anterior end of the organism – associated with movement
Chapter 32 An Introduction to Animal Diversity1. What is an animal?2. How did animals evolve?3. How are animals grouped & characterized?
- Body plans- Symmetry & tissues - Body cavities
- Acoelomates – without a body cavity- Pseudocoelomates – “false body cavity” – cavity not completely
lined with tissue derived from mesoderm- Coelomates – body cavity completely lined with tissue
from mesoderm
Figure 32.8 Body plans of triploblastic animals
CoelomBody covering(from ectoderm)
Digestive tract(from endoderm)
Tissue layerlining coelomand suspendinginternal organs(from mesoderm)
PseudocoelomMuscle layer(from mesoderm)
Body covering(from ectoderm)
Digestive tract(from ectoderm)
Body covering(from ectoderm)
Tissue-filled region(from mesoderm)
Digestive tract(from endoderm)
Coelomate. Coelomates such as annelids have a true coelom, a body cavity completely lined by tissue derived from mesoderm.
(a)
Pseudocoelomate. Pseudocoelomates such as nematodes have a body cavity only partially lined by tissue derived from mesoderm.
(b)
Acoelomate. Acoelomates such as flatworms lack a body cavity between the digestive tract and outer body wall.
(c)
Chapter 32 An Introduction to Animal Diversity1. What is an animal?2. How did animals evolve?3. How are animals grouped & characterized?
- Body plans- Symmetry & tissues - Body cavities- Developmental plan
- Protostome- Deuterostome
Figure 32.9 A comparison of protostome and deuterostome development
Protostome development(examples: molluscs, annelids,
arthropods)
Deuterostome development(examples: echinoderms,
chordates)
Eight-cell stage Eight-cell stage
Spiral and determinate Radial and indeterminate
Coelom
Archenteron
BlastoporeMesoderm
Coelom
BlastoporeMesoderm
Schizocoelous: solidmasses of mesodermsplit and form coelom
Enterocoelous:folds of archenteronform coelom
Anus
Anus
Mouth
Mouth
Mouth developsfrom blastopore
Anus developsfrom blastopore
Cleavage. In general, protostome development begins with spiral, determinate cleavage. Deuterostome development is characterized by radial, indeterminate cleavage.
(a)
Coelom formation. Coelom formation begins in the gastrula stage. In protostome development, the coelom forms from splits in the mesoderm (schizocoelous development). In deuterostome development, the coelom forms from mesodermal outpocketings of the archenteron (enterocoelous development).
(b)
Fate of the blastopore. In protostome development, the mouth forms from the blastopore. In deuterostome development, the mouth forms from a secondary opening.
(c)
Digestive tube
Figure 32.10 One hypothesis of animal phylogeny based mainly on morphological and developmental comparisons
Po
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“Radiata” Deuterostomia Protostomia
Bilateria
Eumetazoa
Metazoa
Ancestral colonialflagellate
Figure 32.11 One hypothesis of animal phylogeny based mainly on molecular data
Cal
care
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Sil
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Cte
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“Radiata”
“Porifera” Deuterostomia Lophotrochozoa Ecdysozoa
Bilateria
Eumetazoa
Metazoa
Ancestral colonialflagellate
Figure 32.12 Ecdysis
Ecdysozoa – secrete an exoskeleton and moltNematoda & Arthropoda
Figure 32.13 Characteristics of lophotrochozoans1
00
m
Apical tuftof cilia
Mouth
Anus
(a) An ectoproct, a lophophorate (b) Structure of trochophore larva