This is an un-named species of Dunaliella, a green alga and member of the phytoplankton that is often associated with hypersaline conditions. The chloroplast is bowl-shaped and fills the base of the cell. There is a yellowy eyespot to the left side of the plastid in this image. The nucleus with nucleolus lies near the front of the cell. There are two equally long flagella which beat in a breast-stroke motion. Phase contrast micrograph.
Image by B. L. Dicks and D. J. Patterson Image copyright: D. J. Patterson, image used under license to MBL (micro*scope).
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From the collection
Microbes of Mono Lake
|Description of Dunaliella: Cells mostly radially symmetrical, sometimes bilaterally symmetrical, flattened, dorsoventrally curved or slightly asymmetrical; cell shape ellipsoidal, ovoid, cylindrical, pyriform, or fusiform to almost spherical; cell size and shape may vary within a given species depending on different environmental conditions; cell surface smooth with distinctive mucilaginous cell coat; flagella 2, of equal length; chloroplast single, cup-, dish-, or bell-shaped; pyrenoid basal with continuous starch shell; eyespot anterior; nucleus anterior; Golgi bodies (2-4) parabasal; contractile vacuoles absent (freshwater species of doubtful affiliation); asexual reproduction by longitudinal division of vegetative flagellate cells; asexual cysts subspherical, thick-walled with bumpy surface; sexual reproduction isogamous, gametic fusion involves flagellar agglutination and activation of mating structures; several species are homothallic, the type species is reported to be heterothallic; zygote with a thick, smooth wall; after a resting stage, the zygote forms 32 progeny cells, which are liberated through a rupture in the zygote cell wall; meiosis takes place during germination of the zygote; habitat euryhaline or hypersaline. |