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Superphylum Lophotrochozoa
Phylum Bryozoa


  • Tiny colonial animals (zooids).
  • Range from mm to m in size.
  • Adult colonies are sessile and usually attached to hard substrates though some can be found encrusting on seaweed. Some colonies are erect and plant-like and can be up to 1 m across.


  • Bryozoans, or moss animals, are in fact colonies.
  • Larvae of bryozoans are called cyphonaute larvae, and come from non-brooding bryozoans.
  • Approximately 5,000 known living species.

Distinguishing characteristics

  • Larvae are triangular in shape and greatly compressed.
  • Each lateral surface covered by a chitinous valve.
  • Apical tuft of cilia present.


  • Prefer warm tropical waters, but occur worldwide.


  • Cyphonautes develop in the plankton from small eggs and grow extensively during a planktonic stage.
  • Only larvae of non-brooding bryozoans possess a functional digestive tract and feed during their larval existence.
  • Larvae that feed might live in the plankton for several months, while those from non-brooding species are non-feeding and have a very brief larval existence prior to settling.
  • Upon settling, the larvae attach via adhesive sacs and metamorphose to the adult form.