Hydractiniidae
Hydractinia epiconcha
The Hydractiniidae are a family of marine hydroids common worldwide ( Hydrozoa ). The family currently includes about 100 species. The oldest evidence of the family come from the Lower Cretaceous; questionable are reports from the Jura.
Geographic occurrence and life
The family is distributed worldwide. The main application area is in the cooler waters of the northern hemisphere. The colonies often live as Epizoen on the casings of live snails, but even as a coating on stones.
System
The scope of family is quite inconsistent in the literature. While Bouillon & Boero (2000) only list the genus Hydractinia among the family and the genus " Kinetocodon Kramp, 1921 " (recte Kinetocodium Kramp, 1921) under " incertae sedis Hydractiniidae " Peter Schuchert has the " Hydrozoa Directory " of the family six genera about. Daly et al. (2007) stated that the family contains seven genera. The "World Register of Marine Species", however, leads eleven valid species on ( and seven junior synonyms ). Miglietta et al. (2009) then listen additionally Hansi Ella Bouillon 1980 and Tregoubovia Picard, 1958, moreover, the generic name Stylactaria Stechow, 1921 and Podocoryna Sars, 1846 re-used, which are discussed in other publications as junior synonyms of Hydractinia.
- Clava Gmelin, 1790
- Clavactinia Thornely, 1904
- Cnidostoma Vanhoffen, 1911
- Cystactinia Brooks, 1964
- Fiordlandia Schuchert, 1996
- Hydractinia van Beneden, 1844 Stachelpolyp ( Hydractinia echinata )
This family includes, depending on the publication up to 12 valid genera.