Individual zooids are usually less than 1 mm in size but colonies may be 0.5 m or more in diameter. These animals are rapid colonziers and colourful additions to reef habitats, forming calcareous encrustations to continental shelf frameworks and inshore rocks. The phylum Ectoprocta has both freshwater and marine species. The marine representatives, one of the most poorly known groups of marine invertebrates, can be found in great abundance and diversity in the correct environmental conditions. They are thought to have a wide global distribution within the topical and sub-tropical belts.
Bryozoans are moderately tolerant of variations in environmental conditions.
They prefer well-oxygenated, clear, moderately agitated waters. They are themselves predated by echinoids and nudibranchs , and are ocasionally parasitized by animals such as nematodes. Click here to view the 'Picture of the Week' archive.