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9/5/11
1
PhyllumPorifera:SpongesChapter12
Ini5allynotconsideredanimalsbutmolecularevidencedemonstratethatspongesarephylogene5callygroupedwithothermetazoa(animals)
PhylumPorifera
• Poriferansareahighlysuccessfulgroup• Diversifica<oncentersontheiruniquewater‐
currentsystemanditsdegreeofcomplexity.• Theirbodyisanassemblageofcellsembeddedin
anextracellularmatrixandsupportedbyskeletonofspiculesandprotein
Spongesarethesimplestmul5cellularanimals
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PhylumPorifera
• Bodypores‘os5a’,canals,chambersthatformanuniquesystemofwatercurrents
• Mostlymarine
• Radialsymmetryornone
Whatisasponge?
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PhylumPorifera
• Bodyisanaggrega<onofseveraltypesofdifferen<atedcellsforvariousfunc<ons:– Pinacocytesandarchaeocytes:flat
intheoutersurface,feeding– Choanocytes:flagellated,create
currents– Archaeocytesoramoebocytes:
diges<on– Skeletalelements
Whatisasponge?
PhylumPorifera
• Bodyconsistofagela<nousproteinmatrix(mesohyl‐func<onsasanendoskeletoninmostsponges)andcalcareousorsiliceousspiculesand/orspongin
• Noorgansortrue<ssues
• Diges<onintracellular,excre<onandrespira<onbydiffusion
Whatisasponge?
spongin
spicules
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PhylumPorifera
• AlladultsaresessileandaUachedtothesubstratum
• Asexualreproduc<onbybudsorgemmules
• Sexualreproduc<onbyeggsandsperm=freelivinglarvae
Whatisasponge?
gemmules
Spongelarvae
PhylumPorifera
• Embeddedinmesohyl• Linecanalsandchambers• Theflagellumisexposedandits
surroundedbyacollarmadeofmicrovilli
• Thebea<ngflagellumpullswaterthroughthecollartrappingfoodpar<cles
• Thefoodpar<cleisthenpassedtoneighboringcellscalledarchaeocytesfordiges<on.
• Diges<onisintracellular• Choanocytesalsohavearolein
reproduc<on
Typesofcells:Choanocytes
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PhylumPorifera
• Alsoknownasamoebocytesbecauseoftheirshape
• Movewithinthemesohyl• Theyphagocy5zepar<clesat
thepinacodermandreceivedfromchoanocytes
• Theycandifferenciateinanyotherkindofcell.
Typesofcells:Archaeocytes
TypesofamoebocytesincludeSclerocytes:secretespiculesSpongocytes:secretesponginCollencytes:secretecollagenLophocytes:secreteadifferentypeofcollagen
PhylumPorifera
• Closesttoatrue<ssueinsponges:– Pinacocytescells=pinacoderm– Flat– Caningestfoodbyphagocytosis– Helptoregulatesurfaceareaof
thesponges– Somearemodified‐contrac<le
myocyteslocatedaroundosculaorporestohelpregulaterateofwaterflow
Typesofcells:Pinacocytes
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PhylumPorifera
• Collectpar<clesfromthewaterpumpedthroughtheinternalchannels=suspensionfeeding.
• Waterentersthroughsmallincurrentporescalleddermalos5alocatedintheouterlayer=pinacoderm
• Insidewaterpassthechoanocyteswherefoodpar<clesarecollected
• Choanocytespassesfoodtoamoebocytes(archaeocytes)
• Othercellsinvolvedinnutri<on=pinacocytes
Feeding
PhylumPorifera
• Therearethreemaindesignforaspongebody:– Asconoid:choanocyteslieinthe
spongocoel
– Syconoid:choanocyteslieincanals
– Leuconoid:choanocyteslieindis<nctchambers
Canalsystems
Asconoid
Syconoid
Leuconoid
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Asconoid Syconoid Leuconoid
Thesethesethreesystemdemonstrateanincreaseincomplexityandefficiencyofthewaterpumpingmechanisms,buttheydonotimplyanevolu<onarysequence
Theleuconidsystemshowsanincreaseinsurfaceareasoitefficientlymeetsfooddemands.Thistypeofsystemhasevolvedindependentlymul5ple5mesinsponges.
PhylumPorifera
• Collectpar<clesfromthewaterpumpedthroughtheinternalchannels
• Waterentersthroughsmallincurrentporescalleddermalos5alocatedintheouterlayer=pinacoderm
• Insidewaterpassthechoanocyteswherefoodpar<clesarecollected
Reproduc5on:Asexual
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PhylumPorifera
• Mostspongesaremonoecious(hermaphrodites)• Spermarisesfromchonocytes• InCalcareaandDemospongiaeoocytesalsoarisefrom
chonocytes• Inotherdemospongiaespongesoocytescanderivefrom
archaeocytes• Externalfer<liza<on
Reproduc5on:Sexual
Demospongiae
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PhylumPorifera
• Inviviparousspecies‐thezygoteisretainedinandderivesnourishmentfromitsparent
• Thenthezygotedevelopsinaciliatedfree‐livinglarva• Thespermisreleasebyanindividualandthechoanocytesof
anotherindividualphogocy<zethespermtransformingthemselvesincarriercells,takingthespermthroughthemeshohyltotheoocytes.
Reproduc5on:Sexual
Demospongiae
PhylumPorifera
• Inoviparousspecies‐bothoocytesandspermarereleaseintothewatercolumn
• Thefree‐livinglarvae=parenchymulaissolid‐bodiedisthemostcommon,butthereareother6typesoflarvae.
• Spongesexhibitdirectdevelopment.Flagellatedcellsmigratetothecenterandbecomechoanocytes
Reproduc5on:Sexual
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PhylumPorifera
• Calcareousspongesahollowblastulaisformed(stomoblastula).Thenturnsinsideoutexposingdirectlytheflagellatedcells(micromeres).
• Intheamphiblastulatheflagellatedcellsareintheinteriorpart,whichthenbecomechonocytes&amoebocytes
• Non‐flagellated(macromeres)cellsareintheposteriorpartandbecomenthepincaderm
Reproduc5on:Sexual
DevelopmentofthecalcareoussyconoidspongeSycon
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PhylumPorifera
• Classifica<on– ClassCalcarea– ClassHexac<nellida– ClassDemospongiae
5,000–10,000knownspecies
PhylumPorifera
• ClassCalcarea– Spiculesofcalciumcarbone– Spiculesaremonaxonsor3‐4rays
– Smallandtubular– Marine– Canalsystems:asco,syco,andleuconoid
Examplesseeninthelab:Sycon,Leucosolenia
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PhylumPorifera
• ClassHexa5nellidae– Spiculesofsilica– Spiculesare3D– Vaseorfunnelshaped– Canalsystems:syco,andleuconoid
– Deepwater,marine– Bodycomposedofa<ssuecalled
trabecularre5culum,whichisbilayerwithamoebocytesorchoanoblasts
Examplesseeninthelab:Euplectella
PhylumPorifera
• ClassDemospongiae– 95%ofthelivingspeciesarehere– Spiculesofsilica,butnotrayed– Spiculesmaybeboundtogether
withspo
– ngin– Marineandfreshwater– Canalsystems:leuconoid
Examplesseeninthelab:Spongia
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Carnivoresponges!SpongesofthefamilyCladorhizidaeareespeciallyunusualinthattheytypicallyfeedbycapturinganddiges<ngwholeanimals.That'sright,thesespongesareactuallycarnivorous!TheycapturesmallcrustaceanswiththeirspiculeswhichactlikeVelcrowhentheycomeincontactwiththecrustaceanexoskeletons.Cellsthenmigratearoundthehelplesspreyanddiges<ontakesplaceextracellularly.
Par5cipa5on4:Awhatclassbelongthecarnivoresponges?Howdotheytraptheirprey?
Inaddi5onReviewQues5ons:Cap.12preguntas2,3,4,5,6,910,
ForMondaynextweek