-Prokaryotic.
-Formerly known as Blue-Green Algae, but this is a misnomer, they are not algae, but are bacteria.
-Photosynthetic, with pigments chlorophyll a and the accessory pigments phycocyanin (blue) and phycoerythrin (red).
-Reproduce by fission.
-Surrounded by a jellylike sheath.
Lab Examples:
1) Oscillatoria, looks like green spaghetti under the microscope. Grows in long chains called trichomes.
2) Nostoc, commonly called witch's butter or starjelly. Forms large, grape-like colonies. Trichomes consist of small vegetative cells and larger, thick-walled heterocysts in which nitrogen fixation occurs. Looks like a green, beaded necklace.
3) Gloeocapsa, characterized by a thick, gelatinous sheath enclosing vegetative cells. Form clusters of cells and therefore has a colonial body form.
4) Merismopedia, also forms colonies of tiny, green, spherical clusters in rectangular shapes.
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