DEVELOPMENT OF THE AXIAL SKELETON IN WOLFFISH, ANARHICHAS-LUPUS (PISCES, ANARHICHADIDAE), AT DIFFERENT TEMPERATURES

The ontogeny of the axial skeleton, in particular the caudal skeleton, is described from embryos to adult specimens in common wolffish, Anar hichas lupus. The eggs were incubated at constant temperatures of 7.0, 11.0 and 13.0 degrees C. High egg mortality and structural changes in skeletal development (fusion of parts, absence of distal radials and most of dorsal and anal fin rays, abnormal neural arches and dorsal fi n rays) were observed at 13 degrees C. The frequencies of some anomali es were lower at 11 degrees C than at 13 degrees C. The main reason of structural changes of the skeleton at high temperature is the breakin g of normal correlations between developmental rates of some cartilagi nous structures and other tissues and organs of the embryo. These data suggest an epigenetic mechanism of skeletal evolution.