The Giant Pyrosome is a free-floating, colonial tunicate that is made of thousands of identical clones, together forming a hollow cylindrical structure that can be 60 feet (18 m) long and wide enough for a person to enter. Each individual clone is a small, complete animal that filters water, nonstop, in order to obtain food, flush out waste, and contribute to the propulsion of the entire super-organism. These clones have a notochord (“spinal” chord) and are therefore chordates, along with all vertebrates, including people.
Giant Pyrosomes are bioluminescent (light producing), giving rise to the common name, which comes from the Greek for fire (“pyro”) and body (“soma”). The light produced by Giant Pyrosomes is particularly bright and long lasting and is beautiful to witness. Because the individual tunicates can reproduce via cloning, the colony can regenerate injured parts or continue growing after being broken apart. Unless all individual clones are killed at the same time, a colony can theoretically live forever, shrinking and growing based on available food and physical disturbance. Individual clones are hermaphroditic; they make both eggs and sperm. When two colonies meet in the open ocean, individuals likely engage in sexual reproduction. The colonies also reproduce asexually, by budding off tiny starter colonies that contain a few individual clones. Giant Pyrosomes are closely related to other pelagic tunicates (such as the salps) and more distantly related to benthic tunicates (called ascidians) and vertebrates.