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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