Monterey Bay Aquarium Research Institute
Marine Botany

Gonyaulax Morphology

dino drawingdino drawingdino drawing

ventral and dorsal views of dino


Gonyaulax is like an armoured knight, measuring approximately a quarter of a millimeter. During its motile stage it is surrounded by a cellulose theca or amphiesma. It is comprised of outer and inner continuous membranes, between which lie a series of flattened vessicles. The plates of the theca are divided by sutures that accomodate growth.

Gonyaulax has two flagella, the morphological characteristic that inspired the name, "dinoflagellate". "Dinos" is Greek for "whirling", while "flagellum" is Latin for "whip". The two flagella are dissimilar. One lies in the sulcus, the groove that runs from the center to the posterior end of the theca. It propells the dinoflagellate anteriorly and and acts as a rudder, controlling its direction. The other flagella is flattened like a ribbon and is nestled in the cingulum, the groove that runs around the equator of the organism. The part of the cell above the cingulum is termed the epitheca while that below is called the hypotheca. Each flagella emerges from its own flagellar pore.

motile vegetative dino

Gonyaulax polyedra with the theca in its motile (vegetative) stage.
Note the cingulum and the sulcus.

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© 1999  Allison Arnold and Monica Draghici.     All rights reserved.

Last updated: Feb. 05, 2009