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13 Cards in this Set
- Front
- Back
Cnidarian - general characteristics
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- all aquatic, mostly marine
-multi-cellular, with tissue - radial symmetry -polyp and medusa forms - single body cavity -dibloblastic - nematocysts -mesoglea |
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In which phylum do multicellular organisms first occur?
In which physlum do tissue differentiation first occur? |
- porifera are the first multicellular organisms
- cnidarians are the first to differentiate tissues |
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what is dibloblastic and in which phylum does it occur
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dibloblastic indicates the occurance of 2 tissue layers (epidermis and endodermis).
this occurs in the phylum cnidaria |
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Cnidarian - what are the 2 tissue layers and their functions. what is the third layer not counted?
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epidermis- outer layer of skin used for protection
endodermis - lines the stomach and digests food, gastrodermis. gland cells also secrete enzymes mesoglea - gelatinous matric inbetween epi and endodermis'. very few cells and used for flotation and strength |
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nematocysts - what are they, which phylum do they occur, what do they do?
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nematocysts are stinging cells found in the phylum cnidaria. they lie within cnidocytes and are used for feeding and protection.
-each nematocyst can only be used once. they are shot out with high pressure.can be found in tentacles etc of the jelly fish |
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Cnidarians - locomotion, body support
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larva cilliated, adult polyp is sessile, medusa uses pumping body contractions
support - hydrostatic skeleton, chitinous sheath |
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Cnidarians - what classes are the medusa stage not present?
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Class anthozoa
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Cnidarians - what classes are the medusa the dominant form
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class scyphozoa and class cubozoa
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Cnidarians - reproduction
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- asexual (in polyp) via budding and fragmentation
- sexual. alternate generations. planula larvae settle and form polyp stage. polyps produce medusa which are sexually reproductive (diecious) -also release gametes into water. coral spawning occurs Nov-Dec |
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Cnidarians - feeding and nerve system
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feeding - most carnivourous. use tentacles to capture prey and guide food into mouth
-some use zooxanthellae -simple nerve net |
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Cnidarians (class hydrozoa) -what is it's dominant stage. what type of polyp does it form?
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-poly form is dominant
- medusa absent in some species polyp - branched with hydrenth (feeding apparatus -tentacles, hyptosome and mouth), gonangium (surrounds gonopore -location of gonads), and medusa buds |
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Cnidarians (class scyphozoa) -
what is it's dominant stage? what type of polyp does it form? |
medusa is the dominant stage. polyp is small and short lived.
polyp forms stacks of developing medusa. one tall polyp with no branches. however early stages have tentacles |
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Cnidarians (class anthozoa) -
what is it's dominant stage? how does it feed? |
-ONLY stage is polyp. no medusa form.
-feeds via tentacles as well as zooxanthellae (require sunny shallow areas) |