Giant Pyrosome Pyrosoma spinosum
The individuals that make up this giant, floating, colonial tunicate are only about 1 in (2 cm) long, but the giant pyrosome colony, which resembles a gigantic hollow tube, can be large enough for a person to fit inside. Each individual lies embedded in the wall of the tube, with one end drawing in nutrient-laden water from outside and the other end expelling water and waste inside. The expelled water is used to propel the giant pyrosome colony as a whole. A wave of bioluminescent light travels along the community if it is touched.