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Phylum Echinodermata

BIO 2215

Oklahoma City Community College

Dennis Anderson

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Phylum Echinodermata

• Radial symmetry• No head or brain• Spiny skin• Water vascular

system• No excretory organs• Deuterostome• Bilateral lavrae

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PoriferaPorifera PlatyhelmithesPlatyhelmithes MolluscaMollusca ArthropodaArthropoda

HemichordataHemichordataCnidariaCnidaria NemerteaNemertea AnnelidaAnnelida

EchinodermataEchinodermataChordataChordataLophophoresLophophores

ProtozoansProtozoans

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Class AsteroideaStar Fish

• 5 or more tapering arms

• Mouth on underside• Endoskeleton

– Ossicles

• Tube feet• Feed on molluscs and

sea urchins

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Aboral SurfaceAboral Surface

Madreporite

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PedicellariaPedicellaria

SpineSpineSpineSpine

PedicellariaPedicellariaPedicellariaPedicellaria

DermalDermalbranchiabranchia

DermalDermalbranchiabranchia

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Class AsteroideaClass Asteroidea

Aboral surfaceAboral surface Oral surfaceOral surface

Tube feet andTube feet andambulacral ambulacral groovegroove

Tube feet andTube feet andambulacral ambulacral groovegroove

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Water vascular systemWater vascular system

MadreporiteMadreporiteMadreporiteMadreporite

Ring canalRing canalRing canalRing canal

Stone canalStone canalStone canalStone canal

Radial canalRadial canalRadial canalRadial canal

Lateral canalLateral canalLateral canalLateral canal

Tube feetTube feetTube feetTube feetPolianPolianvesiclesvesicles

PolianPolianvesiclesvesicles

Tiedemann’sTiedemann’sbodiesbodies

Tiedemann’sTiedemann’sbodiesbodies

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Tube feetTube feet

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Tube footTube foot

Lateral canalLateral canalLateral canalLateral canal

AmpullaAmpullaAmpullaAmpulla

Body wallBody wallBody wallBody wall

Tube footTube footTube footTube foot

Retractor Retractor musclesmusclesRetractor Retractor musclesmuscles

SuckerSuckerSuckerSucker

Podial musclePodial musclePodial musclePodial muscle

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Movement of tube feetMovement of tube feet

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Water-Vascular System of a Sea Star

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Body Wall and Internal Anatomy of a Sea Star

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Feeding

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Class OphiuroideaBrittle Stars and Basket Stars

• Central disc with distinct arms

• No pedicellariae• Tube feet lack

suckers and ampulla

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Brittle starBrittle star

Bursal slitBursal slitBursal slitBursal slit

MouthMouthMouthMouth

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Basket Star

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Class EchinoideaSea Urchins

• Shell (test) encloses body– Ossicles form plates

• No arms• Long spines

– Movement– Venom

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Internal Anatomy of a Sea Urchin

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Class EchinoideaSand Dollar

• Burrow in sand

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Sand dollarSand dollar

MadreporiteMadreporiteMadreporiteMadreporite

GonoporeGonoporeGonoporeGonopore

Ambulacral regionAmbulacral regionAmbulacral regionAmbulacral region

LunuleLunuleLunuleLunule

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Class HolothuroideaSea Cucumbers

• Soft body with reduced ossicles

• Tentacles near mouth• Respiratory tree

– Breaths through anus

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Class Cridoidea Feather Stars and Sea Lilies

• Most primitive• Feather like arms

used for suspension feeding– Plankton

• Tube feet trap planktonic organism

• Cilia in ambulacral grooves carry food to mouth

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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Class Crinoidea: Sea LilyAttach to substrate with stalk

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Class Crinoidea: Feather StarSwim and crawl

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Central diskCentral disk

AnusAnusAnusAnus

MouthMouthMouthMouth

PinnulePinnulePinnulePinnule

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Ancestral EchinodermsAncestral Echinoderms

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Ancestral EchinodermsAncestral Echinoderms

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The End