Marine Invertebrate Zoology
Invertebrate
Classification and
Relationships
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Invertebrate Classification & Relationships
The Meek Will Inherit the Earth
Why Study Invertebrates?
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Many diseases that effect
humans and the animals
we depend on are caused
by invertebrates
Invertebrates are the base
of most food webs
Invertebrates are the base
of many medical studies:
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Control of gene expression
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Aging, cell death, fertilization and
chemoreception
Transmission of nerve impulses,
biochemical basis of learning and
memory
Genetic basis for the
predisposition for major diseases
(i.e. type II diabetes)
Isolating unique chemicals for
biomedical reasons
Using invertebrates as indicators
in monitoring aquatic systems for
pollutants Invertebrate Classification &
Relationships
Invertebrate Classification and
Relationships
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Classification by cell #, and body symmetry
Classification by developmental pattern
Classification by evolutionary relationship
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Methods used in deducing evolutionary
relationships
Classification by habitat and lifestyle
Invertebrate Classification &
Relationships
Classification by Cell #, and Body
Symmetry
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Cell Number
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Metazoans
Unicellular
Body Symmetry
Asymmetrical
Bilateral
Radial
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Invertebrate Classification &
Relationships
Classification by Developmental
Pattern
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Multicellular animals have been divided into
two groups based on the # of germ layers
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Germ layer
 Diploblastic
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Ectoderm
Endoderm
 Triploblastic
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Most metazoans are triploblastic
Mesoderm
Invertebrate Classification &
Relationships
Classification by Developmental
Pattern
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Triploblastic animals can be classified even
further
Pseudocoelomate
Acoelomate
Coelomate
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Invertebrate Classification &
Relationships
Different Developmental Types
Triploblastic
Acoelomate
Pseudocoelomate
Protostomes
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Coelomates
Deutrostomes
Invertebrate Classification &
Relationships
Advantages of the Coelom
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The digestive system is independent of the
body wall and locomotory activities
Room for the gut, gonads, and embryo’s to
bulge
Fluid in coelom can distribute oxygen, nutrients
and hormones through the body
Fluid filled coelom leads to more effective
locomotory systems
Invertebrate Classification &
Relationships
Classification by Evolutionary
Relationship
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By far the most familiar is the frame work
created 250 years ago by Linnaeus
Organisms grouped in a taxon show a high
degree of similarity
Kingdom
Family
Phylum
Genus
Class
Species
Binomial nomenclature
Order
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Invertebrate Classification &
Relationships
Deducing Evolutionary
Relationships
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How do we compile evolutionary relationships?
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In what ways are evolutionary relationships
depicted?
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PCR (polymerase chain reaction)
Cladograms
Invertebrate Classification &
Relationships
Classification by Habitat and
Lifestyle
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Terrestrial, marine, or aquatic
Intertidal or subtidal
Mobile, sessile, or sedentary, planktonic
Herbivores, carnivores, suspension feeders,
deposit feeders, filter feeders
Symbiotic associations
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Ectosymbionts
Endosymbionts
Mutualism, commensalism, parasitism
Invertebrate Classification &
Relationships
Classification
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The 5 Kingdoms we use today.
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Monera: single celled, prokaryote organisms
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Protista: single celled, contains nucleus and internal
subdivisions
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Diatoms, dinoflagellates, and protozoans
Fungi: multicellular, no photosynthesis, nutrition by
absorption
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Cyanobacteria (blue-green algae)
Mushrooms
Plantae: multicellular, autotrophs
Animalia: multicellular, heterotrophs
Invertebrate Classification &
Relationships
Multiple Kingdom and
Domain Classification