Morphology of larval, postlarval, and early juvenile stages of the red king crab is described and illustrated from laboratory reared material; attention is directed to certain aspects of morphology not previously considered. Some behavioural patterns are clarified, with special emphasis on locomotion and feeding. Morphological criteria for distinguishing the first two juvenile stages are proposed; additional morphological criteria for distinguishing zoeal stages are reported. Data on development and growth rates under laboratory conditions at 7–8°C are given for early life history stages. No major morphological differences were observed between early life stages of the red king crab from the native area in the Pacific Ocean and from the Barents Sea.

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The freshwater fauna of nine caves in central Abkhazia, western Caucasus, revealed 35 species of stygobionts, including 15 new species to be described elsewhere. The number of species per station increased from the depth towards the entrance in caves Golova Otapa and Abrskila, becoming the highest in the epigean part. In both caves, two abundance peaks of aquatic invertebrates were registered: one in the entrance area, associated with the development of amphibiotic insect larvae, the other in the depths due to the high numbers of stygobionts. In Cave New Athos, the highest species richness and abundance were observed in large lakes. In caves Golova Otapa and Abrskila, two faunistic complexes with complementary distributions were found, the first due to amphibiotic insects in the cave entrance area, the second one composed of stygobionts in the deep areas. The impact of anthropogenic factors on aquatic cave communities was also noted. The stygobiotic faunas of all caves studied were clearly divided into three groups, following the number of river valleys in which they were situated. The stygobiont faunas of the caves located within one river valley appeared to be 50% similar. In contrast, the fauna composition of the stygobionts from caves situated in different valleys shared not more than 12% species in common. Stygobiotic shrimps and gastropod mollusks show profound local endemism. Stygobiotic Amphipoda penetrating the ground waters revealed wide distributions between cave systems within a single karst massif. RESEARCH ARTICLE Subterranean BiologyPublished by The International Society for Subterranean Biology A peer-reviewed open-access journal Elena S. Chertoprud et al. / Subterranean Biology 18: 49-70 (2016) 50

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Phototactic responses of light-adapted zoeae IV, glaucothoe, and first stage juveniles of the red king crab to three intensities of white light were quantitatively measured under laboratory conditions. All stages observed were photopositive to all light intensities tested, except for late glaucothoe (10 days since moulting) which did not respond to light stimuli. Phototactic response changed in the early life history of the red king crab. The extent of photopositive movement decreased after each metamorphosis. Peak phototactic response in zoea IV were observed at a light intensity of 1.9 Â 10 13 q cm À2 s À1 , in early glaucothoe at 1.1 Â 10 10 q cm À2 s À1 and in juveniles at 1.3 Â 10 9 q cm À2 s À1 . The data on behavioural responses to light may provide a better understanding of the early life history, survival and recruitment of the red king crab and assist the development of feasible methods and techniques for aquaculture of this species.