Ossetra genitive case form "осетра" (osetra, 'of sturgeon') of the Russian word "осётр" (osyotr 'sturgeon') from the phrase "икра осетра" (ikra osetra, 'caviar of sturgeon'). At one time, the term "ossetra" simply referred to Russian sturgeon species harvested for this type of caviar. In Russian, there are different names for the species of sturgeon that live in various territories such as "Beluga" ("Huso huso"), Sevruga ("Acipenser stellatus") and Sterlet ("Acipenser ruthenus"). The name Ossetra corresponds to the species "Acipenser gueldenstaedtii", which is much smaller than Beluga sturgeon ("Huso huso"), and has a firmer texture. In the territory of the Russian Federation
Types of membership of Opus Dei for the contributions that they may have made to Opus Dei during their time in the organisation, this applies to all categories of membership. When, however, someone leaves the prelature unlawfully (i.e. without the permission of the Prelate) he or she commits mortal sin. Nevertheless, the Congregation for Bishops states: "The laity incorporated in the Prelature Opus Dei continue to be faithful of the dioceses in which they have their domicile or quasidomicile and are, therefore, under the jurisdiction of the diocesan bishop in what the law lays down for all the ordinary faithful". Types of membership of Opus Dei