Phylum Echinodermata Notes - Sardis Secondary Echinodermata...General characteristics Hard, spiny, or bumpy endoskeleton covered with a thin ... Phylum Echinodermata Includes ...

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PhylumEchinodermataBiology11 Spiny Radialsymmetry Watervascularsystem EndoskeletonGeneralcharacteristics Hard,spiny,orbumpyendoskeletoncoveredwithathinepidermis. Endoskeletoncomposedofcalciumcarbonate(limestone). Somespinesaremodifiedintopedicellariae forprotectionorselfcleaning. Canbeeitherrigid(aswhenwetrytopulloneoffofarock)orveryflexible(whenrightingitself),sinceendoskeletonismadeofplatesjoinedbymuscleswhichcancontractorrelax.Endoskeleton Enablessessile&slowmovinganimalstosensepotentialfood,predators,andotheraspectsoftheirenvironmentfromalldirectionsRadialSymmetry 1.ClassAsteroidea: Ex.Seastars Mostspecieshave5ormorearms 2.ClassOphiuroidea: Ex.BrittleStar&basketstar Compactsize;movequickly ArmsusedformotilityEchinodermDiversity 3.ClassCrinoidea: Ex.Sealilies&featherstar Fewlivingspeciesremain Sealiliesareattachedtotheoceanfloor Featherstarsbeginattachedbutbreakawayandswimfreely 4.ClassEchinoidea: Ex.Seaurchin&sanddollar Bodiesshapedlikespheresordisks;noarms Solid,internalshell SpecialfeedingstructurescalledAristotleslantern:madeupoffivesharp,triangulartoothlikesstructuressurroundingthemouthEchinodermDiversity 5.ClassHolothuroidea: Ex.Seacucumber Noarms;elongatedbody Bilaterallysegmented LieandmoveononesideonlyEchinodermDiversitySeaStars(ClassAsteroidea) Radialsymmetry Haveadorsalandventralside,butnoanteriorandposteriorends Fivepartbodyplan NOcephalization(i.e.nobrain)SeaStarGeneralCharacteristics MovementcarriedoutbyWATERVASCULARSYSTEM WVS:Anetworkoffluidfilledtubesthatenabletheseastartomove AlongtheundersideofeachoftheseastarsarmsaremanypairsofTUBEFEET Tubefeet:externalstructuresofthewatervascularsystem OntopofeachtubefootisanAMPULLA Ampulla:muscularsacthathelpsforcewaterthroughtheWVS Musclesoftheampullaecontract,pushingwaterintothetubefootcausingittoextend Whenthefootattachestoasurface,itcontracts,pushingthewaterbackintotheampullaeandpullingtheseastarforwardSeaStarMovementandSupport Systemenablesthemtomove,exchangegases,capturefood,andexcretewastes Waterentersthemadreporite ringcanallongradialcanals hollowtubefootSeaStarWaterVascularSystem(WVS) Allechinodermshaveamouth,stomachandintestines. Seastarsarecarnivorous Feedonmollusksbyextrudingtheirstomachthroughtheirmouthontothefood. Tubefeetaidinpryingapartshellsofmollusks. Powerfulenzymesaresecretedbyapairofdigestiveglandsineacharm Thestomachthenabsorbstheliquidfood.(Nointestineneeded).SeaStarDigestion Thereisaheartlikesacunderthemadreporite thatpushesfluidnearlyidenticaltoseawaterthroughthecoelem,bathingallorgans Thefluidiskeptinmotionbybeatingcilia. Skingillsandtubefeetbringinoxygentothisfluid.SeaStarCirculationofNutrients Wastesareflushedfrombodythroughthetubefeetorskingills. Aseastaralsohasananus,locatedinthecenterofthedorsalside.SeaStarExcretion Nobrainorevenfusedganglia,onlyacentralnerveringthatsurroundsthemouth Nervesextendfromthenerveringdowneachray(belowradialcanals)intoanervenetthatissensoryandcoordinatesmovement Nosensoryorgans,onlycellsthatdetectlight&touch Haveeyespotsattheendofeacharmthatallowthemtodetectlight,andchemicalreceptorsontheirtubefeetSeaStarNervousSystem Seastarsareseparatelysexed. Twoovariesortesteslieinthecornersofeacharmandopendirectlytotheexterior SpawningbyonecanresultinthosenearbytoalsospawnSeaStarReproduction SeaStarsPhylumEchinodermataIncludes BrittleStars Fragile:rayswillbreakoffwhenpickedup.PhylumEchinodermataIncludes SeaUrchinsandSandDollars Coveredinspines. NoraysPhylumEchinodermataIncludes SeaCucumbers Leatherycoveringallowsflexibility. Whenthreatened,mayexpeltubesfromanusorreleaseinternalorganstoconfusepredator.PhylumEchinodermataIncludes SealiliesandFeatherstars Featheryarmsallowittoswim.PhylumEchinodermataIncludes Seadaisies Tubefeetlocatedaroundedgeofdisk. Lessthan1cmindiameter Discoveredin1986PhylumEchinodermataIncludes

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