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  • Characteristic genus: Cryptomonas
  • Abundant in freshwater and marine systems
  • Appearance: small (3-50 µm) biflagellate cells
  • Flagella emerging from apical depression (vestibulum)
  • Auxotrophic: at least one vitamin B is required
  • Pigments: Chl.a, c, a- and b-carotene, alloxanthin, phycoerythrin or phycocyanin
  • Phycobilins are not organized in phycobilisomes as in cyanobacteria and red algae but are located within the            lumen of the thyllacoids
  • Secondary plastids with nucleomorph 
  • Storage product: starch
  • Heterotrophic, uncolored forms with colorless plastids or without plastids

  • Periplast: organic plates underneath cell membrane
  • Ejectisomes: large, ejectile organelles along the vestibulum; discharged upon disturbance, e.g. grazer, attack, change in pH, temperature, osmotic pressure

  • Flagella carry 1.5 µm long hairs and organic scales; hairs are thought to increase flagella efficiency in swimming; long hairs = mastigonemes
  • Flagellar apparatus: cluster of posteriorly directed microtubuli called rhizostyle

  • Asexual reproduction by mitosis and cytokinesis, cells continue to swim
  • Plastids: nucleomorph is divided prior to mitosis; nucleomorphes move to opposite ends of the plastid
  • Mitosis: partial breakdown of nuclear envelope and division spindle at the cell poles
  • Cytokinesis: along cell axis, starting from posterior end (in contrast to Euglenophytes!)
  • Resting cysts: round, thick extracellular matrix, pink color
  • Sexual reproduction observed in some species: Proteomonas exhibits two morphologically distinct growth forms, one of which possesses twice the DNA amount
  • Gamete fusion not observed in Proteomonas, but in Chroomonas acuta: isogamy, flagella of gametes are not involved in fusion as is the case in other algal groups

Cryptophyte Ecology
  • Occurrence: particularly in oligotrophic lakes and oceans
  • Temperature range: prefer temperate and high-latitude environments, rarely at temperatures above 20°C
  • Significance: can form substantial part (up to 70%) of phytoplankton in Antarctic lakes and winter/early spring communities in the North and Baltic Seas
  • Depth distribution: in lakes typically at greater depths, forming a subsurface chlorophyll maximum
  • Nutrition: use organic forms of nitrogen and ammonium, low uptake capacities for nitrate
  • Phagotrophy and Osmotrophy has been demonstrated for at least some species
  • Endosymbionts in the marine, olbigate phototrophic ciliate Mesodinium rubrum, which can produce red-colored, non- toxic blooms in upwelling areas