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Plankton:thedri4ers

Phytoplankton•  Photosynthesize–baseoftheenergypyramid

TwogeneralcategoriesofPlankton

•  Phytoplankton:thosethatphotosynthesize(photoautotrophs),andproduceoxygen–  Picoplankton,nanoplankton,microplankton– Nanoandmicroplankton:

•  Diatoms(Bacillariophytes)•  Dinoflagellates(dinophyta)

•  Zooplankton:animalplankton– Holoplankton–staybasplanktonalltheirlives– Meroplankton–alarvalstageisplanktonic,thentheybecome‘nekton’

PlanktonAdaptaQons

•  Smallsize•  Complexshapes•  Slowsinkingrates•  Fatsandoils**•  Cysts(dormancy)forbadcondiQons•  Spines(limitgrazingpressure)

**Mostneedtobenearthesurfacewhy?

•  Manyplanktonformthe‘deepscaWeringlayer’andmigrate,o4enfromdeepduringtheday(fewpredators)tothesurfaceatnight(tofeed)

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Diatoms,BacillariophytaFigure28.17Diatoms(PhylumBacillariophyta):oneoftheheterokontalgae.Diatomshaveuniqueglass‐likecellwallsmadeofsilica.TheyareVERYabundantas“plankton”inthesurfacewatersoflakes,rivers,andoceans.Theyreproducesexuallyonlyrarely.

Diatoms:Bacillariophyta•  Photoautotrophs•  Solitaryorcolonial•  Makeupphytoplanktoninoceans,lakes,streams‐extremelyimportantcontributorstoglobalOxygen!

•  Silicacellwalls•  PrimarilyasexualreproducQon,diploid‐somesexualreproducQon

•  Formauxospores‐resQngstage•  Chlorophyllaandcandfucoxanthin(acarotenoid)

Pseudo‐nitzchiaaustralis

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pennatevs.centricshapes DiatomLifeCycleasexualReproducQon

Adiatomfrustule

TheygetsmallerwithsuccessivegeneraQons!

Figure28.15Diatomshell.Note:diatomshaveatwo‐partcellwall,oneofwhichfitsinsidetheotherlikethepartsofashoebox. DiatomaceousEarth

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Figure28.10DinoflagellatesspinduetothebeaTngofapairofspiralflagellalyinginagrooveencirclingthecell. Figure28.9Alveolatesarecharacterizedbymembrane‐boundsacs(alveoli)beneaththeplasma

membrane.

Dinoflagellates(Dinophyta)•  MostlyphosyntheQcautotrophs,someareheterotrophic

•  Unicellular•  2flagella(many)•  Chlorophylla&c,carotenoids(peridinin)•  Cellulosecellwall(ornone)•  Manyarebioluminescent•  SomearemutualisQcsymbiontsinmarineinvertebrates

•  SomespeciesareresponsibleforredQdes(toxins)

Dinoflagellates:Dinophyta

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Pfiesteria‐killsandtheneatsfish!

Zooxanthellae‐keystocoralreefproducQvity

Figure32.1Acoralreef.Coralsarecolonialanimals,withphotsyntheTcdinoflagellatesymbionts. Zooplankton:animals

Holoplankton:stayplanktontheirwholelife

Copepods:importantgrazersintheplanktonworld

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MEROPLANKTON:Willstayplanktonpartoftheirlives.Theyareusuallylarvae,Manywillgrowtobefamiliarorganismssuchasfish,urchins,Squidetc.