Zooids are located in the wall of the cylinder, embedded in the common tunic; the oral siphon of each zooid faces outwards, whereas the atrial aperture opens into the central cloacal cavity: water expelled through the cloacal aperture allows colonial locomotion by propulsion.

Where are bryozoans found?

Worldwide, bryozoans are found on every continent except Antarctica. Although most bryozoans are marine, one class (Phylactolaemata) lives only in freshwater. About 20 freshwater species occur on our continent. These usually prefer the rather quiet waters of lakes, ponds, and swamps, but some live in streams.

Is a zooid a polyp?

branches bear the individuals, or zooids (hydroid polyps). Each zooid consists of a tubular body that has two layers separated by a thin jellylike mesoglea (layer of connective tissue), a terminal mouth, and surrounding circlet(s) of tentacles. The zooids are joined basally to a common living tube called the stolon…