Аннотация:Starfish of Asterias genus (fam. Asteriidae, ordo Forcipulatida, cl. Asteroidea) are widely distributed in the oceans. The best known of these are two species: the Atlantic A.rubens Linnaeus, 1758 and the North Pacific A. amurensis Lütk, 1871. The 5'-fragment of mitochondrial COI genes in A. rubens and A.amurensis as well as internal transcribed spacers 1 and 2 were sequenced after amplification in PCR. The obtained sequences were aligned with homologous sequences of other species of the North Atlantic and Pacific sea stars, taken from GenBank (www.ncbi.nlm.nih.gov), and held their phylogenetic analysis using the software package MEGA 5 (Tamura et al., 2011). The results of the analysis indicate a high degree of interspecies insulation between the types studied in this paper. The level of intraspecific divergence estimated from genetic distances within species clusters, ranging from 0.003 to 0.009, while the level of interspecific divergence, as measured by genetic distance between species clusters, ranging from 0.104 to 0.298. Analysis of the current geographical distribution of the genus Asterias points to inhabit two species in the North Atlantic. A. forbesii dwells on the shelf of the North American coast from Cape Hatteras to Cape Cape Cod, north of the area, which extends A. rubens. European populations inhabit the shelf of the European Atlantic coast of Iceland to the west of France. The U.S. population A. rubens originally were referred to the species A. vulgaris. Areas of North American populations of A.forbesi and A. rubens overlap to a large part of the shelf around Cape Cape Cod (Franz et al., 1981). Large genetic distances between populations of these species indicate a lack of cross-species hybridization. Paleontological data show that the penetration of the genus Asterias in the North Atlantic there were at least 3.5 million years ago, followed by trans-Arctic migration was interrupted due to climate change [Worley, Franz, 1983]. This date is the starting point for determining the time of divergence between the North Pacific and North Atlantic sea A.amurensis taxa (Wares, 2001). Our results show that the genetic distance between the North Atlantic taxa no less than between A.amurensis and North Atlantic taxa. Consequently, the exchange of genes between the North Atlantic populations of A. forbesi and A. rubens, too, had to be interrupted not later than 3.5 million years ago.