Аннотация:Today we understand that molecular data or morphology description at certain stages ontogeny considered independently and out of context of organism development do not help greatly in understanding of phylogeny of certain taxa. Detailed investigations of the organism development and its morphological alterations during entire ontogeny are required for interpreting both the peculiarities of organism structure and the origin of such peculiarities in the phylogenetic context. As an example we present the data on metamorphosis of scyphozoan larva Aurelia aurita. In spite of being a textbook 'organism' the details of scyphozoan larva development and metamorphosis remained till now obscure. The larva competent for metamorphosis is composed of two distinct tissue layers. Our investigations reveal that during settlement and metamorphosis into primary polyp such larval organisation undergoes certain alteration. As a result the lining of the gastric cavity of the primary polyp has double origin: the inner surface of manubrium originates from ectoderm of the larva posterior pole. These finding are in contradiction with previous data (Yuan et al., 2008). We argue that revealed mode of scyphozoan larva metamorphosis is the modified and simplified variant of anthozoan primary polyp with ectoderm pharynx development.