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The life cycle of Daphnia commonly includes parthenogenesis, sexual reproduction, and diapause. Although there are no genotypic transformations during diapause, it separates the 'clonal' and 'pseudopanmictic' states of the population. During parthenogenetic reproduction primarily polymorphic natural populations gradually degenerate into a mixture of a few clones. As resting eggs are usually produced sexually (= by means of sexual reproduction), after the diapause the vast diversity of individual genotypes normal for panmictic populations is observed. It is the competitive interactions between parthenogenetic clones which again eventually decrease the genotypic polymorphism. Forms in which the sexual process and diapause are rare (or species which are represented by parthenogenetic populations in one part of their area and by bisexual ones in another) demonstrate the most significant differences between clonal and panmictic populations.Parthenogenesis, apomixis and other kinds of reproduction without genetic recombination are widely spread in branchiopod crustaceans (Notostraca, Anostraca, 'Conchostraca', 'Cladocera') and in many other animals and plants. Moreover, reproduction without recombination plays an important role in evolution of faunas and floras. It is emphasized that non-recombinating races and species having high heterozygosity but a low level of genetic variation, enjoy short term advantages, but die out after change in the environment.

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Two arctic species of sea anemones of the family Halcampidae are redescribed basing on newly collected specimens. The type material of Cactosoma abyssorum and its subjective synonym Phellia crassa is revised. It was shown, that the syntypes of Phellia crassa belong to at least three species. A lectotype was selected from the type material of Phellia crassa. Phellia crassa remains a junior synonym of Cactosoma abyssorum.

The results of an investigation into coelenteron content of the Antarctic sea anemone Urticinopsis antarctica Carlgren, 1927 are presented. Remains of invertebrate animals and fishes were found in the gastrovascular cavity of anemones. Some of them were damaged by digestion and were considered as food items of U. antarctica. These items were molluscs Addamussium colbecki (Smith, 1902), Laevilacunaria pumilia Smith, 1879, Eatoniella caliginosa Smith, 1875 and one not strictly identified gastropod species from the family Rissoidae; a crinoid from the family Comatulida; sea-urchin Sterechinus neumayeri Meissner, 1900; ophiuroid Ophiurolepis brevirima Mortensen, 1936 and a fish Trematomus sp. In contrast to the prey mentioned above, three specimens of amphipods Conicostoma sp. were not destroyed by digestion. They may represent commensals, which live in the gastrovascular cavity of the anemone.