BOT4404 Main Page

FIU Home

FIU Marine Biology Home

Dept. Biology Home

Frank Jochem Home


  • Small group of few, mainly marine genera
  • Appearance: 30-80 µm, long anterior flagellum with perpendicular tripartite hairs, smooth flagellum motionlessdirected backwards; naked cells without scales or cell cover
  • Trichocysts can be ejected and produce long mucilaginous strands
  • Mucocysts can produce extracellular mucilage
  • Metabloy is documented for some species
  • Pigments: Chlorophyll a and c, but some species lack chl.c; marine species possess fucoxanthin and violaxanthin, whereas freshwater forms possess diadinoxanthin and others
  • Pyrenoids in marine but not freshwater sp.
  • Phototrophic, phagotrophy and sexual reproduction not observed
  • Fish kills are cause by blooms of Heterosigma and Olisthodiscus (marine)

Chrysophytes (Chrysophyceans)
  • Name: gr. Chrysos = gold; „golden algae“; 
  • Color golden brown by their predominant accessory pigment fucoxanthin
  • Appearance: unicellular flagellates or flagellated colonies, sometimes non-motile unicells, colonies, or amoeboid stages that produce flagellated spores
  • Habitat: mostly freshwater, but also marine species; prefer slightly acidid water (pH<7), probably because they posses an acidic but no alkaline phosphatase (enzyme to degrade organic phosphates); abundant in the periphyton (communities living on macroalgae)
  • Stomatocysts are heavily silicified resting stages resulting from sexual or asexual reproduction; fossil records of chrysophycean stomatocysts and their distinct surface structure (electron microscope) are used for geological studies; only 10% of stomatocysts have been connected to vegetative taxa

  • Nutrition in Chrysophytes
    • Nutrition: most species mixotroph, among them chlorophyll-containing species that act primarily as heterotrophs and use photosynthesis only in times of scarce food supply

      Dependence of Ochromonas growth on bacteria abundance
    • Important grazers on bacteria and picoalgal communities in freshwater and marine systems 
    • Freshwater blooms of chrysophyceans can cause fish kills by toxins or gill clogging
    • Water odor can arise from excretion of ketons and aldehydes by chrysophyceans
The „Other“ Chrysophyte: Hydrurus
  • Hydrurus foetidus Kirschner (1618) 

  • Olive-green, feathery tufts, 1-30 cm. long, develops an offensive odor sticky to touch; occasionally encrusted with calcium carbonate; in running, cold fresh water.