Avicularia are categorised by their position relative to the autozooids. Vicarious avicularia effectively replace an autozooid in the colony structure and are usually a similar size and shape as the autozooids. Interzooidal avicularia are wedged between autozooids but do not replace an autozooid. Adventitious avicularia are placed somewhere on the external (frontal) wall of an autozooid and are usually much smaller. The 'birds-head' avicularium (e.g. Bugula) is elevated above the colony by a stalk (peduncle).
A zooid where the operculum is modified into a very long, hair-like structure is called a vibraculum.
MORPHOLOGICAL DIFFERENTIATION OF AVICULARIA AND THE PROLIFERATION OF SPECIES IN MID-CRETACEOUS WILBERTOPORA CHEETHAM, 1954 (BRYOZOA: CHEILOSTOMATA)
Jan 01, 2006; ABSTRACT- Discovery of avicularium-like polymorphs in Wilbertopora mutabilis Cheetham, 1954 has provided not only a new...