Family OPHRYDIIDAE Ehrenberg, 1838

Body bottle-, vase-, or spindle-shapéd, often with long and highly contractile neck, elongate macronucleus, and aborally located contractile vacuole; solitary (first genus) or forming often huge (up to 15 cm in diameter) gelatinous "spherical" colonies (green-colored from endosymbiotic zoochlorellae in the individual zooids); arypical stalk, sometimes of long peduncular fibers; bonafide species perhaps exclusively fresh-water forms.

Gerda Claparéde & Lachmann, 1858 (resurrected genus). Few species.
Ophrydium Bory de St. Vincent, 1826. Few species.