Pyrosomes are free-floating colonial tunicates in family Pyrosomatidae. Pyrosomes consist of colonies of small Zooids. There are three genera, Pyrosoma, Pyrosomella and Pyrostremma, and eight species. They usually live in the upper layers of the open ocean in warm seas, although some may be found at greater depths. Pyrosomes exhibit bioluminescence, and the name Pyrosoma derives from the Greek words pyro, meaning "fire", and soma, meaning "body". Pyrosomes are hermaphroditic and reproduce via a two-part process.