genus of small marine jellyfish of the class Hydrozoa (phylum Cnidaria). Its medusoid body is characteristically hemispherical and measures up to about 30 mm (1.2 inches) in diameter. Eight short tentacles hang down from the edges of the body, and a shorter stalklike structure, the manubrium, containing the mouth, extends downward from the centre. It is commonly believed that only one, if highly variable, species exists (Liriope tetraphylla). It is found in the warm parts of the Atlantic and Indo-Pacific oceans. The liriope does not begin as a sessile (attached) form; the fertilized eggs develop directly into small medusae. Lacking a sessile stage, liriopes do not need a solid substrate during their life cycle and so are not restricted to coastal waters. They sometimes occur in great shoals near the surface.