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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