Bryozoan Statoblasts

The Bryozoa (Phylum Ectoprocta), also known as Polyzoa in some older literature, is a group of small, sessile, colonial, filter-feeding animals. The majority of the members are strictly marine, but there are at least 65 freshwater species worldwide (Wood & Wood, 2000). The phylum is divided into three classes: the Stenolaemata which are exclusively marine; the Gymnolaemata which are mostly marine but have a few freshwater members in the order Ctenostomata; and the Phylactolaemata which are exclusively freshwater. Only species in the Phylactolaemata produce encapsulated dormant structures called statoblasts, and thus this discussion will be confined mainly to this group.