Tetrabaena, a green alga (Chlorophyta) in which four cells form a colony within a delicate mucoid matrix. Each cell with two apical flagella that beat with a breast-stroke pattern. This image was taken by William Bourland. He now uses a Zeiss Axioskop 2 with Spot Insight and Spot Flex CCD cameras (Diagnostic Instruments). Image copyright: William Bourland, image used under license to MBL (micro*scope).
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From the collection
Freshwater and Terrestrial Microbes of Idaho (USA) and Elsewhere
|Description of Tetrabaena: Colonies plate-shaped, square, with generally 4 cells oriented with their longitudinal axes more or less in the same direction; individual extracellular matrix zone with protuberances forming connections with adjoining cells; cells also held together by fragile gelatinous capsule zone outside tripartite boundary surrounding entire colony; cells ovoid or nearly spherical, with 2 equal flagella; chloroplast single, cup-shaped, with a single (rarely 2) basal pyrenoid(s) and an anterior or nearly median eyespot; contractile vacuoles 2, anterior; asexual reproduction by formation of daughter colony by each cell; sexual reproduction isogamous, homothallic or heterothallic; each cell escaping from its cellular sheath to become a spherical gamete; only one of the two conjugating gametes bearing a mating papilla; zygotes spherical, with a reticulate wall; on germination, 4 biflagellate gone cells liberated separately; nutrition apparently obligately phototrophic; commonly found in freshwater, especially in pools and ponds |