basal metazoans
DESCRIPTION
BASAL METAZOANS. A body plan, baupläne , ground plan, ground pattern , or bodyplan , is "an assemblage of morphological features shared among many members of a phylum-level group". Bauplan (pl. Baupläne ) The generalized body plan of an archetypal member of a major taxon. Look at 4 groups. - PowerPoint PPT PresentationTRANSCRIPT
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BASAL METAZOANS
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Bauplan (pl. Baupläne) The generalized body plan of an archetypal member of a major taxon.
A body plan, baupläne, ground plan, ground pattern, or bodyplan, is "an assemblage of morphological features shared among many members of a phylum-level group"
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Look at 4 groups
1. Placozoa
2. Cnidaria
3. Ctenophora
4. Platyhelminthes
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PLACOZOA
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PLACOZOA
Distribution
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PLACOZOA
1) Asymmetric.
2) No distinct tissues or organs.
3) No nervous system.
4) No body cavity or digestive cavity.
5) Body is shaped like a flat disc.
6) Two layers of single cells.
7) Marine.
8) One species only known Trichoplax adhaerens
Characteristics of Placozoa
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PLACOZOA
Cover cells
Cylinder cells
Gland cells
Fibre cells
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PLACOZOA
Placozoan movement
Feeding -
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PLACOZOA
Reproduction
1. Binary fission
2. Budding
3. Sexual
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PLACOZOA
Reproduction
1. Binary fission
2. Budding
3. Sexual
“hollow swarmer”
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PLACOZOA
Reproduction
1. Binary fission
2. Budding
3. Sexual
“hollow swarmer”
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PLACOZOA
Reproduction
1. Binary fission
2. Budding
3. Sexual
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PLACOZOA
Reproduction
1. Binary fission
2. Budding
3. Sexual
oocyte
yolk
zygote
Fertilization membrane
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CNIDARIA
ANTHOZOA
CUBOZOA
HYDROZOASCYPHOZOA
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Diploblasty
Gastroderm
Ectoderm
Mesoglea
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CNIDARIA
Feeding
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CNIDARIA - EMBRYOLOGY
Stereogastrula
Radial and holoblastic cleavage
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CNIDARIA – PLANULA LARVA
Ectoderm
Endoderm
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CTENOPHORA – COMB JELLIES
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CTENOPHORA – BIRADIAL SYMMETRY
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Tentacle
Statocyst
Tentacle sheath
Meridional canal
Stomadeum
Pharynx
Mouth
Anal pore
CTENOPHORA
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Muscle fibres
CTENOPHORA TENTACLE
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Ctenophora video
CTENOPHORA – SUPPORT & LOCOMOTION
Locomotion
- Comb rows
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CTENOPHORA FEEDING - COLLOBLASTS
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CTENOPHORE - STATOLITHS
- Balancing organ
Statocyst
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CTENOPHORA – REPRODUCTION AND DEVELOPMENT
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CTENOPHORA – REPRODUCTION AND DEVELOPMENT
1. Form blastomeres – meridional cleavage
2. Third division – 8 macromeres
3. Fourth division – latitudinal and unequal - micromeres
5. Macromeres invaginate (gastrulation)-micromeres become ectoderm-macromeres become endoderm
6. Just before gastrulation –- Produce additional micromeres on oral side – invaginate to form stomatodeum4. Micromeres divide and spread over
aboral pole and macromeres
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Cleavage in PleurobranchiaCleavage in Beroe
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CTENOPHORA LARVAE
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COMPARISON OF CNIDARIA AND CTENOPHORE
CNIDARIA CTENOPHORA
Diploblastic with acellular mesoglea Diploblastic (triploblastic?) with cellular mesenchyme
Radial symmetry Biradial symmetry ; oral/aboral axes
Nematocysts Colloblasts
Gastrovascular body cavity Gastrovascular body cavity
Nerve net More specialized nerve net
Musculature – extensions of epithelial cells Musculature – from mesenchyme cells
Alternation of generations No alternation of generations
Planula larva Cydippid larva
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PLATYHELMINTHES
Who are they?
Turbellaria(flatworms)
Trematoda (flukes)
Monogenea (flukes)
Cestoda (tapeworms
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PLATYHELMINTHES
Common trends
1. Triploblastic acoelomates
2. Cephalization and central nervous system
3. Mesoderm – fibrous and muscular mesenchyme
4. Osmoregulatory structure - protonephridia
5. Elaborate reproductive systems
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PLATYHELMINTHES
Limiting factors
l. Lack of efficient circulatory system
2. Lack of gas exchange system
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TRIPLOBLASTY
Ectoderm Mesoderm Endoderm
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TURBELLARIA – MAJOR ORGAN SYSTEMS