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13 Cards in this Set

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  • Back
Cnidarian - general characteristics
- all aquatic, mostly marine
-multi-cellular, with tissue
- radial symmetry
-polyp and medusa forms
- single body cavity
- nematocysts
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
what is dibloblastic and in which phylum does it occur
dibloblastic indicates the occurance of 2 tissue layers (epidermis and endodermis).
this occurs in the phylum cnidaria
Cnidarian - what are the 2 tissue layers and their functions. what is the third layer not counted?
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
nematocysts - what are they, which phylum do they occur, what do they do?
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
Cnidarians - locomotion, body support
larva cilliated, adult polyp is sessile, medusa uses pumping body contractions
support - hydrostatic skeleton, chitinous sheath
Cnidarians - what classes are the medusa stage not present?
Class anthozoa
Cnidarians - what classes are the medusa the dominant form
class scyphozoa and class cubozoa
Cnidarians - reproduction
- 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
Cnidarians - feeding and nerve system
feeding - most carnivourous. use tentacles to capture prey and guide food into mouth
-some use zooxanthellae
-simple nerve net
Cnidarians (class hydrozoa) -what is it's dominant stage. what type of polyp does it form?
-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
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
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)