Download - Phylum Cnidaria

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Page 1: Phylum  Cnidaria

Phylum Cnidaria

Page 2: Phylum  Cnidaria
Page 3: Phylum  Cnidaria

What are Cnidarians?http://www.youtube.com/watch?v=wOXO4F9

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Groups of CnidariansJellyfishes (class Scyphozoa – cup animals)Hydras (class Hydrozoa)*Sea anemones (class Anthozoa – flower

animal)*Corals (class Anthozoa – flower animal)*

*only have polyp stage of life cycle

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QuestionsWhat domain are we focusing on in this

class?What kingdom are we focusing on?What is the phylum for jellies, coral, hydras,

sea anemones?

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Characteristics of CnidariansSoft-bodiedCarnivorousHave stinging tentacles arranged in a circle

around their mouthMost simple animals with body symmetry &

specialized tissues

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QuestionWhy is it important that their tentacles are

arranged around their mouth?

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Where does the name Cnidaria come from?From their stinging cells – cnidocytesThese cells are used for defense and to

capture prey

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NematocystLocated within a cnidocyteThis is the poison filled stinging structure –

has a tightly coiled dart

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Body PlanFew cells thick and have

a simple body systemHave a central mouth

surrounded by numerous tentacles that extend outward from the body.

2 tissue layersEpidermis (outer)Mesoglea (middle goo)Gastroderm (inner)

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QuestionsWhat are the stinging cells called?What is the name of the actual poisonous dart

in the stinging cells?Why is it advantageous to be only a few cells

thick when you are a marine organism?

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SymmetryCnidarians are radially symmetrical

Like spokes on a wheel no matter how you divide it through the middle it is symmetrical

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QuestionsWhat type of symmetry do poriferans have?What type of symmetry do cnidarians have?

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Life CycleTypically have a life cycle that includes two

different-looking stages.PolypMedusa

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PolypCylindrical body with armlike tentaclesThe mouth points upward – why is this

important?Usually sessile

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MedusaMotileBell shapedMouth on bottom – why would their mouth be

on the bottom?

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Cnidarian ReproductionSexual

Typically in the medusa stageTypically have a planula larvae

AsexualTypically in the polyp stage

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Ecological Roles – Predator-PreyCnidarians are predatorsSea turtles, some fish and mollusks will feed

on jellies

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Ecological Relationships - SymbiosisMutualism

Clownfish and anemone

Hermit crabCoral and

zooxanthellae

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Phylum Ctenophora

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Differences/Similarities Between Cnidarians and CtenophoresCtenophores CnidariansGelatinousTransparent bodies*Lack stinging cellsPlanktonicFound mostly in surface

watersLuminescent/IridescentHave 8 rows of comb

platesUsed for locomotion


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