Studying Cyphonautes Larvae of Hislopia prolixa(Bryozoa; Ctenostomata) in Temperate Fresh Water

Abstract

Cyphonautes larvae are confirmed for the first time among the temperate freshwater zooplankton. They are part of the life cycle of the ctenostome bryozoan, Hislopia prolixa Hirose and Mawatari, 2011, known so far from China, Japan, and the Republic of Korea. Until 2008 cyphonautes were thought to be exclusively marine, occurring in three families of ancient ctenostome and cheilostome bryozoans. Since then they have been recognized in several tropical freshwater bryozoan species of the Genus Hislopia. Their presence in temperate latitudes now enlarges the area where these unusual larvae can be studied in their natural habitat. Embryological development in fresh water can be easily observed from egg to larva within a span of 12-24 h. Laboratory culture of the larvae has so far been hampered by their small size, hydrophobic body surface, unknown nutritional requirements, and high mortality rate.