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DescriptionA colonial hydroid that forms a loosely conical colony when small, becoming erect and bushy when large, growing up to 20 cm in height. The main stems are rather thick and the side branches are numerous, tending to be in pairs, successively on opposite sides of the stem as in Obelia bidentata. The hydrothecae, a supporting, nonliving, protein-chitinous envelope surrounding the polyp, is bell-shaped and small. Gonothecae bear 4-6 embryos that are brooded to the planula stage.Reproduction thought to occur from May to August but may be extended from April to November (Cornelius, 1995b). This species may be confused with other Obeliinae e.g. Obelia bidentata, especially when young, however, the main stem of Hartlaubella gelatinosa is darker than its final branches and branching is alternate at right angles to the stem. The taxonomy of Hartlaubella is a matter of debate (see Stapanjants, 1998 for discussion).