Droving behaviour of the ocypodid Ilyoplax deschampsi (Rathbun, 1913) is recorded in Kyushu, western Japan. Droving crabs left their burrows and foraged near the littoral fringe at low tide, on hot summer days in July and August when their breeding season was almost finished. Male and female droving crabs were significantly larger than those remaining in the burrowing area. Droving habit is first recorded for the genus Ilyoplax.

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This study focuses on the life history of the Mediterranean green crab Carcinus aestuarii along the northern shores of Tokyo Bay, Japan. Hand collection, baited traps and artificial cobble habitats were used over a period of two years at two sites, one along a canal and another in a man-made lagoon. Planktonic larvae were also surveyed. Collected crabs were analyzed for size, sex, molting condition, and ovigerous females were recorded. The results showed that the peak of megalopal settlement occurs in March. These settlers (crabs) then grow steadily throughout the summer months, and most females are able to breed during their first year. In autumn, the crabs migrate offshore, where they stay until the following spring. The breeding season lasts from November to May. Survival of larvae released late in the season, however, is lower, most likely due to increased fish predation and also to bottom hypoxia. Size analysis indicates that the crabs live at least three years, and most are able to breed three times during that period. Females, however, appear to be less likely than males to overwinter twice or more. The seasonal patterns of breeding and offshore migration observed here corresponds well with that documented for the Mediterranean green crabs in their native habitat. Since severe bottom hypoxia develops during the summer months in the offshore areas of upper Tokyo Bay, the seasonal migration pattern allows the crabs to avoid this hypoxia while utilizing wide areas of the bay during the autumn and winter months, when oxygen levels have recovered. In addition, the winter breeding habit allows most of the larvae to develop, migrate inshore and settle before predation and early bottom hypoxia become obstacles.

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Intermolt (hard shelled) female Thalamita picta, including ovigerous females, were observed to mate in the field and laboratory. Postmolt (soft shelled) stages did not initiate a mating response in males. Copulation in the laboratory lasted an average of 186.1±66.7 seconds (mean±S.D., n = 16) with no significant difference (P>0.1) in duration between pairs with ovigerous and non-ovigerous females. Further, duration of copulation did not differ significantly (P>0.1) between pairs in which the male was larger than the female and those in which the female was larger than the male. For the pre-copulatory maneuvering period (time between capture of the female and the initiation of copulation), although no significant difference was observed between ovigerous and non-ovigerous females (P>0.1), pairs in which the male was smaller than the female (248.6±180.5 sec, n = 9) differed significantly (P<0.05) from pairs in which the male was larger (75.3±39.6 sec, n = 7). Mating behaviors with the congeneric species T. sima and T. prymna are compared and discussed.

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Two morphological types of terminal moult male Japanese mitten crab Eriocheir japonica sampled from the sea were distinguished from the hair distribution on and relative growth of the chelae. The mating behaviour of the two morphs was observed in the laboratory. Larger males (more than 52 mm in carapace width) in small numbers had proportionally larger chelae with dense hair. Smaller males (less than 62 mm in CW) which were more numerous had relatively small chelae with thin hair. The range in size of the two morphological phases overlapped in carapace and chelar sizes, but were separated into two different growth phases from regression analysis. Both male phases are mature, have spermatophores in the vas deferens, pursue females, copulate, and fertilize eggs. Previous studies have shown that most males die without moulting after the seaward migration and reproduction, suggesting that smaller phase males die without moulting to the larger phase. Further, males of the larger phase do not participate in reproduction while they are small. The significance of the dimorphism in relation to the life history is discussed.

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The intertidal distributions and habitats of three congeneric callianassid shrimps [Nihonotrypaea harmandi (Bouvier), N. japonica (Ortmann), and N. petalura (Stimpson)] were surveyed along the estuary to opensea gradient from Ariake Sound through Tachibana Bay to the East China Sea in western Kyushu, Japan. In the light of long-term-averaged salinity (psu) values hi the surface waters (at 5 m depth) in the rainy season, (N. harmandi + N. petalura) and N. japonica mainly occurred in the ranges of 34.0-30.5 (the East China Sea + Tachibana Bay + the outermost part of Ariake Sound) and 30.5-28.5 (the middle part of Ariake Sound), respectively, with their distribution boundary distinct. Using the Venice-system terms for the clas sification of brackish waters, the former species group could be designated as euhaline to mixo-euhaline species, while the latter species as a mixo-polyhaline species. From the viewpoint of the sub strate conditions and their dimensions, the habitats for the three species were basically characterized, as follows: 1) N. harmandi - the relatively small sandflats and sandy beaches of medium - fine sands, with boulder beaches, very ex posed sandy beaches, and mud flats unin habited; 2) N. petalura - small sand patches surrounded by boulders in boul der beaches; and 3) N.japonica - the ex tensive sandflats of medium - fine sands, with boulder beaches, exposed sandy beaches, and mudflats uninhabited.

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Horizontal starch gel electrophoresis was used to estimate the genetic divergence among the three species of grapsid crabs under the genus Helice: H. tridens latimera, H. t. tridens and H. leachi. Eight out of 25 loci coding 15 enzymes were polymorphic: AAT-1^*, AAT2^*, GPI^*, IDHP^*, MDH-1^*, MDH-2^*, PGDH^* and LDH^*. The average proportion of polymorphic loci and heterozygosity were 0.04 and 0.006 in H. t. latimera, 0.07 and 0.005 in H. t. tridens and 0.05 and 0.004 in H. leachi, respectively. Nei's genetic distance was 0.00033 between H. t, latimera and H. t. tridens, 0.16966 between H. t. latimera and H. leachi, and 0.17017 between H. t. tridens and H. leachi. The results indicate that the degree of genetic differentiation is very small between the species of H. t. latimera and H. t. tridens and higher between H. leachi and the other two species.

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Based on several type specimens and material collected from various localities, the East Asian species of Crangon are revised. C. affinis De Haan, 1849, C. propinquus Stimpson, 1860, C. dalli Rathbun, 1902a, C. hakodatei, Rathbun, 1902b, C. cassiope De Man, 1906, C. amurensis Brashnikov, 1907 and C. uritai new species are recognized. C. affinis is given full specific status. A neotype is designated for C. propinquus. C. septemspinosa forma amurensis and C. septemspinosa forma anivensis are assigned to C. amurensis. The taxonomic status of C. dalli, C. hakodatei and C. cassiope is clarified by the examination of the type specimens and/or topotypic specimens. Each species is diagnosed and illustrated. C. uritai, which had been confused with C. affinis, is fully described and illustrated. Affinities and distribution of these seven species are discussed and a key is provided.

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Coronalpheus natator new genus, new species is described from the Galapagos Islands. It lives under subtidal rocks. It is similar to species of Automate in having the eyes exposed in dorsal view, the pterygostomian angle of the carapace unarmed, the mandible with a palp and molar process, the first pereopods dissimilar and the dactyl carried extended dorsally, the second pereopod with 5 articles in the carpus and epipods on the 4 anterior pairs of pereopods. However, it has an appendix masculina on the second pereopod, the pigmented part of the eye is well developed and there are distinct spinules on the basal article of the antennular flagellum. The rostrum reaches to the pigmented part of the eye. The stylocerite and scaphocerite are well developed. In life, it is colored yellowish with a bright red line along the dorsal midline.

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Galathea amboinensis De Man, 1888 and G. inflata Potts, 1915, both known as associates of shallow water comatulid crinoids, are reported for the first time from Japan. In the Ryukyu Islands, Galathea inflata was found on 13 species of crinoids but most commonly on Comanthus parvicirrus (Miiller) and Comaster schlegelii (Carpenter). Galathea amboinensis 'was recorded from 10 crinoid species but more often on Capillaster multiradiatus (Linnaeus) than on other crinoids. Heterosexual pairs of G. inflata were found on 26.3 % of host crinoids (n=57), and all females were ovigerous. Megalopae of both galatheids were found on hosts, indicating that the larvae settled on crinoids at the megalopa stage.

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Grapsid crabs Hemigrapsus sanguineus infested with Sacculina polygenea were reared in isolation for a maximum of 232 days. Size, colour and morphological features of externae were examined daily. After repeated spawning externae dropped off and new externae appeared. Of a total of 41 newly appeared externae 15 erupted more than 40 days after moulting of host crabs. Ten externae erupted within 3 days after the moult. The externae released nauplii with an average interval of 17.0 ± 2.6 days. Moulting of the inner cuticle of the mantle cavity of the externa occurred 6.2 ± 4.0 days after the release of nauplii. The behaviour of parasitized H. sanguineus at the time of nauplii release was observed. The crabs climbed up on a stone placed in an aquarium and raised their bodies supported by walking legs and chelipeds. The fourth legs were always extended backward. Low frequency pumping movements of the abdomen contributed little to larval release. The nauplii were mainly expelled from the aperture by the contraction and expansion of the externa.

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The grapsid crab Cyclograpsus intermedius Ortmann, 1894 in the Amakusa Islands, Japan, is parasitized by two sacculinid parasites: Sacculina oblonga Liitzen & Yamaguchi, 1999 and Sacculina confragosa Boschma, 1933. Average prevalences at four sites are 1.6 to 12.1 % in S. oblonga and 0.4 to 1.5 % in S. confragosa. The number of externae attached to crabs infected with S. oblonga is only one without exception. Most of the crabs parasitized by S. confragosa had one externa but a few crabs had two or three externae attached. A significant difference in infection rate between the sexes was found in S. oblonga. Female crabs seem to be more commonly infected by the parasite. The morphological modification is more significant in smaller males than in larger crabs.

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Paramunna rhipis new species, is described from Otsuchi Bay, northern Honshu, Japan, the first record of the Paramunnidae from Japan. The new species is distinctive from its congeners in having dorsally located uropods, and laterally expanded lobes of the head bearing a narrow, shallow median notch.

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A survey of the spatial distribution pattern of the gnathiid isopod, Elaphognathia cornigera (Nunomura, 1992), inhabiting the sponge Halichondria okadai (Kadota), was conducted on a rocky intertidal shore on the Izu Peninsula, southern Japan. While the number of adult male Elaphognathia cornigera is related to sponge size, larvae tended to aggregate in smaller sponges. The vertical distribution of the isopod overlapped with that of the sponge. No particular patterns were observed in the distribution of E. cornigera adults, but larvae mainly occurred around mean tide level. This may be explained by the behavior of larvae migrating between sponges and host fishes.

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