An order of the cnidarian class Scyphozoa, usually found in circumpolar regions. Haliclystus auricula is typical. The egg develops into a planula which can only creep since it lacks cilia. The planula changes into a polyp that metamorphoses directly into a combined polyp and medusa form. The medusa is composed of a cuplike bell called a calyx (medusan part) and a stem (polyp part) which terminates in a pedal disk. The calyx is eight-sided and has eight groups of short, capped tentacles and eight sensory bodies, called anchors (rhopalioids), on its margin. The mouth, situated at the center of the calyx, has four thin lips and leads to the stomach in which gastral filaments are arranged in a row on either side of each interradius. Though sessile, the medusa can move in a leechlike fashion by alternate attachment and release of the pedal disk, using the substratum as an anchor.