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31 Cards in this Set
- Front
- Back
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Levels of organization: Cellular |
No true tissues; Sponges May have two primitive tissue layers |
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Levels of organization: Tissue |
No true organs; cnidarians like hydra and jellyfish |
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Levels of organization: Organ |
Organs and organ systems; Majority of Animals |
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Type of Body plan: Sac-Plan |
-incomplete digestive system -one all purpose opening -Cnidarians are some flatworms |
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Type of Body Plan: Tube within a tube plan |
-inner tube is digestive system -outer tube is body wall -two openings majority of animals |
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Types of symmetry: Asymmetrical |
no particular symmetry |
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Types of symmetry: Radial Symmetry |
Circular organization -can be bisected in any plane to produce mirror image halves usually observed in sessile, aquatic forms |
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Types of symmetry: bilateral symmetry |
has definite right and left halves -only a cut down the median plane will produce mirror images |
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Embryonic Germ Layers: Ectoderm |
-outermost layer -gives rise to nervous system and skin |
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Embryonic Germ Layers: Mesoderm |
-middle layer -gives rise to muscles, connective tissues, and circulatory system -not present in cnidarians |
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Embryonic Germ Layers: Endoderm |
-inner layer -gives rise to part of digestive and respiratory tracts |
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diploblastic |
animals that lack mesoderm |
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triploblastic |
have all three germ layers ectoderm endoderm and mesoderm |
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Types of Body Cavities: Acoelomate |
-lacks a body cavity -gut is embedded in solid mass of mesoderm |
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Types of Body Cavities: Pseudocoelomate |
-body cavity incompletely lined with mesoderm -lacks mesenteries |
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Types of Body Cavities: Coelomate |
-possesses true body cavity -contains organs -completely lined with mesoderm visceral organs held in place by mesentaries |
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Metameres |
Repetition of body parts or segments |
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cephalizatin |
development of head with feeding and sensory structures; associated with segmentation |
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Tagmatization |
-the development of groups of body segments fused into functionally distinct body regions ex. the head, thorax, and abdomen of arthropods |
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Jointed Appendages |
-specialized for locomotion -found in arthropods and vertebrates -in arthropods, may be adapted as mouth parts |
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Types of Skeleton: Endoskeleton |
-muscles exterior to skeleton -muscles attach attach across joints |
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Types of Skeleton: Exoskeleton |
-muscles interior to skeleton -muscles still attach across joints |
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Types of Skeleton: Hydrostatic Skeleton |
-muscles work against fluid-filled body cavity |
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Regulatory Genes |
-control when and where other genes get turned on -start a chain reaction of effects - a single regulatory gene can thus control the construction of a body part as complex as a leg or eye -holds the key to the development of embryos |
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Hox Genes |
lay out the basic body forms of many animals, setting up the head to tail organization -in drosophila hox genes are located on 1 chromosome -in humans and mice the same four hox genes are located on four different chromosomes -expressed anterior to posterior |
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Colonial Flagellates |
-may represent the ancestral stock that gave rise to multicellular animals -some stalked, other planktonic -each cell resembles the "collar cells (choanocytes) found in sponges |
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Patterns of Development: Protosomes |
spiral cleavage -schizocoelous coelom formations -mouth forms from blastopore -trochophore larva |
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Patterns of Development: Deuterostomes |
-radial cleavage -enterocloelous coelom formation in lancelets and lampreys, schizocoelous in higher vertebrates -anus forms form blastopore -dipuleurula larva |
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Eumetazoa |
Traditionally all, multicellular animals above the level of sponges |
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ecdysozoa |
protosomes that molt their cuticle |
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lophotrochozoa |
protosomes that dont molt -this scheme is gaining wide accpetance |
