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The Characteristics ofPhylum Cnidaria

The Characteristics ofPhylum Cnidaria

Characteristics of PhylumCnidariaCharacteristics of PhylumCnidaria

• radial symmetry• blind sac gut (= coelenteron or gastrovascular

cavity)• diploblastic with mesoglea• polyp and medusa body forms• nematocysts (= specialized stinging capsules)• nerve net• lack excretory, circulatory & respiratory systems• complex life cycle• many colonial forms exhibiting polymorphism

• radial symmetry• blind sac gut (= coelenteron or gastrovascular

cavity)• diploblastic with mesoglea• polyp and medusa body forms• nematocysts (= specialized stinging capsules)• nerve net• lack excretory, circulatory & respiratory systems• complex life cycle• many colonial forms exhibiting polymorphism

Radial SymmetryRadial Symmetry

aboralaboral

oraloral

Bilateral SymmetryBilateral Symmetry

From The World Book (TM) Multimedia Encyclopedia (c) 1999 World Book, Inc., 525 W. Monroe, Chicago, IL 60661. All rights reserved. !"Charles W. Mann, National Audubon Society from Photo Researchers!

From The World Book (TM) Multimedia Encyclopedia (c) 1999 World Book, Inc., 525 W. Monroe, Chicago, IL 60661. All rights reserved. !"Charles W. Mann, National Audubon Society from Photo Researchers!

From The World Book (TM) Multimedia Encyclopedia (c) 1999 World Book, Inc., 525 W. Monroe, Chicago, IL 60661. All rights reserved. !"World Book illustration by James Teason!

From The World Book (TM) Multimedia Encyclopedia (c) 1999 World Book, Inc., 525 W. Monroe, Chicago, IL 60661. All rights reserved. !"World Book illustration by James Teason!

Blind Sac GutBlind Sac Gut Complete GutComplete Gut

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DiploblasticDiploblastic

gutgut

ectodermectoderm

endodermendoderm mesogleamesoglea

DiploblasticDiploblastic

(from the endoderm)

(from the ectoderm)

TriploblasticTriploblastic Polyp and Medusa Body FormsPolyp and Medusa Body Forms

polyppolypmedusamedusa

POLYP ANATOMY

EPIDERMIS

MESOGLEA

MOUTH

GUT

GASTRODERMIS

TENTACLE

COLUMN

ABORAL

ORALMedusa Body FormMedusa Body Form

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NematocystsNematocysts NematocystNematocyst

NematocystsNematocysts Nerve NetNerve Net

Diffusion Across the BodyWallDiffusion Across the BodyWall

Sea AnemonesSea Anemones

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Circulation in a Moon JellyfishCirculation in a Moon Jellyfish The Cnidarian Life CycleThe Cnidarian Life Cycle

TheCnidarianLife Cycle

TheCnidarianLife Cycle

ColonialityColoniality

From The World Book (TM) Multimedia Encyclopedia (c) 1999 World Book, Inc., 525 W. Monroe, Chicago, IL 60661. All rights reserved. !"(c) Maira & Rod Borland, Bruce Coleman, Inc. !

From The World Book (TM) Multimedia Encyclopedia (c) 1999 World Book, Inc., 525 W. Monroe, Chicago, IL 60661. All rights reserved. !"(c) Maira & Rod Borland, Bruce Coleman, Inc. !

PolymorphismPolymorphism

PolymorphismPolymorphism

fire coralfire coral