I. SYNONYMS: Chrysophytes, chrysomonads, synurids.

II. NUMBER: 1,000 species (120 genera).

III. PHYLUM CHARACTERISTICS:

• A. Structure and Physiology
  • Cell Form: Coccoid, amoeboid, filamentous, colonial, or thalloid, usually flagellated.
  • Flagella: Two flagella; recurrent (text with tooltip) Recurrent flagella bend to the posterior end of the cell. Typically, they are identified as recurrent when anteriorly-directed flagella are present. whiplash (text with tooltip) (1) A whiplash flagellum is a eukaryotic 9+2 flagellum with few or no flagellar hairs or scales. These may be directed anteriorly or posteriorly. (2) A whiplash flagellum is free of hair-like mastigonemes and usually is trailing or posteriorly-directed. and anterior (text with tooltip) An anteriorly-directed flagellum extends in the direction of the motion of the motile cell. The interpretation is that the flagellum functions by pulling the cell. tinsel (text with tooltip) A tinsel flagellum is one that is covered with flagellar hairs and thus appears thicker in light microscopy. Usually, tinsel flagella are anteriorally-directed. with two rows of thick mastigonemes (text with tooltip) Mastigonemes are flagellar hairs. . Chrysomonads with photoreceptive flagellar swelling (text with tooltip) A flagellar swelling is a portion of the base of a flagellum that usually is light sensitive (as in the eyespot apparatus of euglenoids). at the base of the smooth flagellum; associated with an eyespot (text with tooltip) An eyespot is a light-sensitive structure that does not form an image. This can be part of an organelle as in the chloroplast of certain microbial eukaryotes. It can be an elaborate structure that involves a light-sensitive swelling at the base of a flagellum (as in the euglenoids) or it can be a multicellular structure as in planarians. .
  • Basal Bodies: Basal bodies perpendicular (text with tooltip) Basal bodies are perpendicular (or orthogonal) when their orientation relative to each other is at a right angle. (with rhizoplast (text with tooltip) A rhizoplast is a striated root system that extends from the basal body tinto the cell, usually to the nuclear envelope. ?)
  • Cell Covering: Covered by cellulosic wall, large scales (text with tooltip) Protist scales are regular overlapping structures on the outside of the cell. They may be organic, silicaceous, or carbonaceous and may serve as an articulated cell wall. Scales may occur on the cells of a range of unrelated taxa. , a delicate lorica (text with tooltip) A lorica is a covering that occurs outside of the cell membrane. It is secreted by the cell and usually is organic. Loricas do not completely enclose the cell. Periplasts, structures similar to loricas do enclose the cell. Lorica stands for armour. or naked.
  • Chloroplasts: Usually 2 golden brown with chlorophylls a and c1 and c2 (text with tooltip) Chlorophyll C is a variant of Chlorophyll A. and a secondary photosynthetic pigment in the many of the photosynthetic heterokonts and dinoflagellates. , only chlorophyll a and c in synurids. With β-carotene, fucoxanthin (text with tooltip) Fucoxanthin is a carotenoid secondary photosynthetic pigment that occurs in many of the photosynthetic eukaryotes like the heterokonts and haptotists. and other xanthophylls (text with tooltip) Xanthophyll is an oxygenated carotenoid secondary photosynthetic pigment that occurs in many of the photosynthetic eukaryotes. ; 3 thylakoids in the the photosynthetic lamellae; eyespot, when present, situated within the chloroplast.
  • Food Reserves: Chrysolaminarin (text with tooltip) Chrysolaminarin (also called leucosin) is a storage carbohydrate that is a polymer of glucopyranoside units. Typically it is found in photosynthetic heterokonts. and fat; some phagotrophic.
  • Mitochondria: Tubular cristae (text with tooltip) Mitochondrial cristae that form as extended saccate structures or tubes are called tubular cristae. .
  • Golgi (text with tooltip) Golgi apparatus (also called dictyosome) is an internal membrane system of stacked flattened sacs. They occur in nearly all eukaryotes and are involved in storing and secreting cellular products. : Present.
  • Nucleus: Usually haploid; outer membrane confluent with outer membrane of one of the chloroplasts.
  • Centrioles: Basal bodies function as centrioles.
  • Inclusions and Ejectile Organelles: Phagotrophic forms with food vacuoles.

• B. Mitosis, Meiosis and Life History
  • Mitosis: Nuclear membrane breaks down at least a spindle poles; spindle poles associated with rhizoplasts from basal bodies.
  • Meiosis: Present.
  • Sexual Reproduction and Life History: Usually haploid; sex involves fusion of flagellated isogametes (text with tooltip) Isogametes are gametes that are equal in size. ; siliceous (text with tooltip) Silica is silicon dioxide (SiO2). cysts (text with tooltip) A cyst is a resting stage that is covered by a resistant outer covering. Usually, cysts are able to allow the cell to survive environmental extremes. They serve as the infective forms of parasitic protists. Usually in sexual microbial eukaryotic groups, the cyst is produced by the zygote. .

• C. Ecology: Mainly found in fresh water.