Student Project Figures Figure 4 A simplified diagram showing the arrangement of zooids in a colony. The atrial openings of the two zooids converge into a common cloacal (excurrent/exhalant) siphon. Zooids are on average 2 mm in length and colonies can range from 3 to 15 cm in width. Copied from Ruppert et al., 2004.  Figure 2 Figure 3 Figure 4