Pyrosoma
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Pyrosomes, or pyrosoma, are free-floating, ciliated, bioluminescent tunicates that inhabit the plankton layer in the open ocean. Most pyrosoma live in colonies in the tropical seas. The name of their genus, Pyrosoma, comes from the Greek (pyro- = "fire", soma = "body") referring to their bright blue or green bioluminescent glow. They are closely related to salps, and are sometimes called "fire salps."
What appears to be a single long, tube-shaped animal is actually a colony of minute pyrosoma. Colonies range in size from under one centimeter to over one meter in length. They form a hollow tube which serves as a common gut tube from which all the members of the colony absorb nutrients.