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Ch 16 Echinoderms

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PoriferaPorifera PlatyhelmithesPlatyhelmithes MolluscaMollusca ArthropodaArthropoda

HemichordataHemichordataCnidariaCnidaria NemerteaNemertea AnnelidaAnnelida

EchinodermataEchinodermataChordataChordataLophophoresLophophores

ProtozoansProtozoans

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

– For locomotion, respiration, excretion, and food gathering.

– Opens to outside through pores in Madreporite.

• Deuterostome• All marine

Water-Vascular System of a Sea Star

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Star Fish

• 5 or more tapering arms

• Mouth on underside

• Tube feet• Feed on molluscs and

sea urchins

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Aboral SurfaceAboral Surface

Madreporite-opening for water vascular system

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Pedicellaria-tiny jaws that keep surface clean

Pedicellaria-tiny jaws that keep surface clean

SpineSpineSpine

PedicellariaPedicellariaPedicellaria

Dermalbranchia

DermalDermalbranchiabranchia

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Tube feet-for movement. Also help w/ excretion

Tube feet-for movement. Also help w/ excretion

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Brittle Stars and Basket Stars

• Largest group

• Central disc with distinct arms

• No pedicellariae• Tube feet lack

suckers

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Brittle starBrittle star

MouthMouthMouth

Basket Star

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Sea Urchins

• Shell encloses body

• No arms• Long spines

– Movement– Venom

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Sand Dollar

• Burrow in sand

• Compact body in shell

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Sand dollarSand dollar

MadreporiteMadreporiteMadreporite

Ambulacral regionAmbulacral regionAmbulacral region

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Sea Cucumbers• Soft body

• Tentacles near mouth• Respiratory tree

– Breathes through anus

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Feather Stars and Sea Lilies

• Most primitive

• Feather like arms used for suspension feeding

• Tube feet trap plankton

• Cilia in ambulacral grooves carry food to mouth

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Class Crinoidea: Sea LilyAttach to substrate with stalk

Class Crinoidea: Feather StarSwim and crawl

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The End