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Invertebrate Zoology Animals without Backbones
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Patterns of the Invertebrate Symmetry- orientation around a central axis Germ Layers- embryonic tissue Deuterosome vs Protostome Body openings and digestion Coelom development
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Deuterostomes Indeterminate cleavage blastophore becomes anus/second opening becomes mouth radial cleavage-cells of cleavage are aligned
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Protostomes Determinate cleavage in most ( fate fixed early) blastophore develops into a mouth first Spiral cleavage-cells do NOT line up
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Symmetry ( a ) radial- can be divided along any plane, through a central axis into roughly equal halves ( b ) bilateral- can be divided down it’s length only one way into similar right and left halves (not shown asymmetry-irregular in shape
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Germ Layers 1. Ectoderm- outermost germ layer (forms skin, nerves ) 2. Mesoderm- middle germ layer ( forms muscle, kidney, liver etc.) 3. Endoderm- innermost germ layer ( forms digestive and reproductive tract ) 1.1. 2 3
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Mesoderm forms as an outpocketing from endoderm ectoderm endoderm
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Coelom Coelomate- has a true coelom CAVITY WITHIN A BODY Acoelomate- lacks a true coelom Pseudocoelomate- false body cavity ( no mesodermal connection )
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Body Cavity COELOM- true cavity within a body Acoelomate- lacks a true body cavity Pseudocoelomate- has a false body cavity ( cavity develops with no mesodemal connection ) Coelomate- true body cavity developing from out pockets of the mesoderm
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SUMMARY GERM LAYERS 1. Ectoderm- outermost germ layer (forms skin, nerves ) 2. Mesoderm- middle germ layer ( forms muscle, kidney, liver etc.) 3. Endoderm- innermost germ layer ( forms digestive and reproductive tract )
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BODY SYMMETRY Symmetry- orientation around a central axis ( a ) radial- can be divided along any plane, through a central axis into roughly equal halves ( b ) bilateral- can be divided down it’s length only one way into similar right and left halves (not shown asymmetry-irregular in shape
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Invertebrate Phyla
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Porifera Parazoa-lacking true tissue Filter feeders- incurrent and excurrent pore ( oscula choanocytes- collar cells that create current amoebocytes- capture food by phagocytosis Spicules- silica or calcium carbonate skeletal structures Spongin- protein in some species for support Hermaphrodites contain both male and female sex organs BEHAVE LIKE A COLONY
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Cnidarians Eumetazoan- have true tissues Radial symmetry acoelomate- lack a coelom diploblastic- only two germ layers Alternation of generation polyp- plant like medusa- free swimming ( jelly fish like Digestive traffic-two way, gastrovascular cavity-no separate circulatory/digestive system
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Nematocyst- stinging cell
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Sea Anemone
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Phylum Cnidaria Class Hydrozoa hydra Class Scyphozoa jelly fish Class Anthozoa sea anemone
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BUD----- nematocyst
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Platyhelminthes Planaria
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Nematoda Three germ layers Pseudocoelomate One-way digestive pattern Little need for resp. or digestive system Separate sexes Parasitic and free-living
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ectoderm endoderm mesoderm
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Rotifera Mostly freshwater Pseudocoelom with several organ systems Crown of cilia around mouth Both sexual and asexual reproduction
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S- SYMMETRY assymetry GL-GERM LAYERS none BO-BODY OPENINGS many BC-BODY CAVITIES acoelomate DT-DIGESTIVE TRAFFIC none, filter feeds cells digest CS-CIRCULATORY SYSTEM none, filter water to remove water
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