Medusas

Medusas refers to two related concepts in different fields. In biology, medusas (often called medusae) are the free-swimming, bell-shaped life stage of many cnidarians, including true jellyfish and some hydrozoans. In the cnidarian life cycle, individuals typically alternate between a sessile polyp and a motile medusa; medusae reproduce sexually by releasing gametes into the water, where fertilization occurs to form planula larvae. Anatomy generally includes a gelatinous umbrella-shaped bell, tentacles around the edge, and a mouth on the oral surface leading to a gastrovascular cavity. Medusae are commonly planktonic swimmers, moving by pulsations of the bell, though in hydrozoans the medusa stage may be reduced or absent.

In Greek mythology, Medusa is one of the three Gorgons. She is typically depicted as a female figure with serpentine hair whose gaze could turn onlookers to stone. In most traditions she is slain by the hero Perseus, who uses a reflective shield to avoid direct sight and beheads her. From the severed head, Pegasus the winged horse and Chrysaor allegedly spring forth. Medusa’s head, or the Gorgoneion, has appeared as a protective symbol in various works of art and heraldry, and the myth has been interpreted in numerous ways in literature and modern culture.