All jellyfish are Cnidaria, an animal phylum that contains jellies, sea anemones, and corals, among others. There are more than 10,000 species of Cnidaria, and less than 4,000 of these are Medusazoa—those animals we think of as jellyfish. Those 4,000 jellyfish can be divided into four different groups.
Masquerade balls were extended into costumed public festivities in Italy during the 16th century Renaissance (Italian, maschera). They were generally elaborate dances held for members of the upper classes, and were particularly popular in Venice. They have been associated with the tradition of the Venetian Carnival.