Description of Colacium
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Euglenids; with plastids, normally attached by mucilaginous secretions from the canal; cell division occurs to produce bunches, sheets or dendroid colonies of a few to hundreds of cells with thin sheaths, joined together by mucilaginous stalks; settled cells shed the locomotory flagellum but retain the basal portions of their 2 flagella within the reservoir, including the (reduced) flagellar swelling; any cell can regrow the long flagellum, escape from the colony as a free-swimming organism (indistinguishable from Euglena), settle elsewhere and secrete a new stalk and sheath of mucilage; eyespot and flagellar swelling present; plastic, euglenoid movement only slight in colonial state; not flattened; canal opening subapical; freshwater, attached to filamentous algae, aquatic angiosperms, Cyclops, Daphnia and other aquatic animals, including fish; fairly common, worldwide. Type species: C. vesiculosum, Ehrenberg, 1833.
