Laboratory experiments were conducted to study the chemosensation and feeding behavior of red king crab (Paralithodes camtschaticus). Five extracts of squid, herring, mussel, king crab muscle, and king crab ovary were used as test solutions. Change in antennular flicking rate was employed as an index of detecting chemicals. The median effective concentration at which 50% of crabs detected the solution varied between 10^<-4> to 10^<-6> g l^<-1> for the five extracts. Crabs were most sensitive to conspecific muscle, but least to mussel. Movement of maxillipeds, probing of chelipeds, movement of walking legs, and body elevation indicated the onset of feeding behavior. Among these indicators, movement of maxillipeds was the most sensitive. The median effective concentration at which 50% of crabs showed feeding responses ranged from 10^<-2> for ovary to 10^<-3> g l^<-1> for herring extract. Herring was the most effective natural bait for red king crabs, while little difference was detected between the sexes for chemosensation.

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A new rhynchocinetid shrimp, Cinetorhynchus fasciatus, is described and illustrated from three male specimens collected from Chichi-jima Island of the Ogasawara Islands, Japan, and Oahu of the Hawaiian Islands. The new species closely resembles C. hiatti (Holthuis & Hayashi) and C. rigens (Gordon) in the armature of the ambulatory pereiopods, carpi and dactyli in particular, but may be distinguished by the combination of the fourth abdominal somite rounded on the posteroventral angle, the stylocerite not extending beyond the end of the antennular distal segment, the meri of the third and fourth pereiopods bearing two to four spines on the lateral surface, the second maxilliped bearing a developed podobranch, and the distinctive coloration. A modified key to species of the genus is proposed.

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A laboratory experiment compared feeding rate, foraging response, and survival between unfed and fed ovigerous and nonovigerous Dungeness crabs (Cancer magister) over a six month winter period from December 1994 through May 1995. Twenty-four female crabs were collected from Bartlett Cove in Glacier Bay, southeastern Alaska, and separated into 2 treatments, each containing 6 ovigerous and 6 nonovigerous crabs. The treatments were in separate flow-through seawater tanks containing sediment. One treatment was fed a diet of squid while the other was not fed. Feeding rates and foraging responses were measured over a 24 hr period every 2 weeks. Ovigerous females had significantly lower feeding rates (9.0 ± 1.5 g・d^<-1>) than nonovigerous females (16.8 ± 0.4 g・d^<-1>) in the laboratory (two-way ANOVA, P < 0.001). The foraging responses of ovigerous crabs were significantly lower in comparison to nonovigerous females (Chi-squared test, P < 0.01). No mortality occurred in any treatment over the six month experiment, demonstrating that Dungeness crabs can survive over the winter without feeding in laboratory conditions.

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Janetogalathea, a new genus, is proposed for Galathea californiensis Benedict, 1902. It is differentiated from Galathea by an ill-defined orbit, flattish rostrum laterally bearing a small basal and two large anterior spines, third thoracic sternite anteriorly narrowed and contiguous with laterally expanded preceding sternite, and antennal peduncle fused with the orbit.

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Waving displays of the intertidal ocypodid crab Scopimera globosa were observed in the field in relation to other behaviors. Most of the crabs observed to wave were males holding burrows. The proportion of waving crabs was higher in the summer months when ovigerous females and precopulatory behavior (males chasing females) occurred. A negative correlation between waving and precopulatory behavior was found i.e., males performing waving intensively exhibited less frequent precopulatory behavior. However in more than half of the precopulatory behaviors, waving occurred both immediately before and after precopulatory behavior. No correlation was found between the waving frequency and either the frequency of aggressive encounters or the density of neighboring crabs. Immediately before and after an aggressive encounter, the case when waving occurred was observed at a similar frequency to the case when no-waving occurred. These observations suggest that waving in S. globosa functions as a courtship behavior advertising burrowholding males.

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The reproductive behavior of the spiny king crab, Paralithodes brevipes, was observed in the laboratory. Females always molted before mating and extruding eggs. Males performed pre-copulatory guarding behavior before and/or after its mate molted. When males guarded females, prior to the female molting, the average duration from the start of guarding to molting was 38.6 ± 24.9SD hours. Females spawned within 24 hours of molting. Competition among males for females was observed, and larger males appeared to have a competitive advantage although copulation occurred even when males were smaller than their mates.

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Intermolt (hard shelled) female Thalamita prymna, including ovigerous females, were observed to mate both in the field (N=2) and laboratory (N=13). In the laboratory, intermolt males and females showed characteristic stalking and maneuvering behaviors prior to copulation, with copulation lasting 34.5±2.4 minutes (mean±SD). During a 20 month field survey, no guarding behavior or sperm plugs which are characteristic of portunid soft-female mating behavior were observed. A female reared in isolation to maturity over a 6 month period from an immature instar successfully mated during the intermolt stage and produced a fertile egg brood ten days after the single mating. From these observations, hard-female mating is concluded to be the principal mating strategy in T. prymna. Females of the congeneric species T. sima also mate during the intermolt and the contrasting mating behaviors of these 2 species are discussed.

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Larvae of two grapsid crabs, Helice leachi Hess and H. formosensis Rathbun were reared under nine different salinities in the laboratory. The larvae survived to the megalopa stage in 10 to 30 ppt for H. leachi and 15 to 35 ppt for H. formosensis. The best survival of H. leachi to the zoeae (80%) and megalopa (90%) occurred in 20 and 15ppt respectively, at 24-C. In contrast, 30 and 20 ppt showed the highest survival of zoeae (100%) and megalopa (100%) for H. formosensis at 22℃.

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The temporal and spatial distribution of larvae and newly settled juveniles of a stomatopod crustacean Oratosquilla oratorio, (De Haan, 1844) was investigated in the eastern part of the Sea of Hiuchi-Nada, Japan. Occurrence of many larvae to the northwest of Ibuki-jima Island suggests it may be the spawning ground. Larvae are transported counterclockwise around Ibuki-jima Island by a residual current, widely settle in the bottom waters, and metamorphose to benthic juveniles. Newly settled individuals were sampled at most stations in August, but were absent in the southern waters of Ibuki-jima Island in October. Oxygen-deficient waters from August to October may be partially responsible for the distribution of O. oratorio, juveniles in October.

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A dense population of the cirolanid isopod, Eurydice nipponica Bruce & Jones, inhabited an intertidal sand flat in western Kyushu, Japan. Newly-ovigerous female groups occurred twice yearly, during March to June and August to October, generating two major recruitment groups: June to July (summer group) and September to November (autumn group). The summer group became ovigerous after 2 mo, with most of the early recruits to the group dying out after breeding (3-5-mo life span). Some of the later summer recruits overwintered to have their second brood, dying out during spring to summer. Members of the autumn group overwintered to have their first brood during late spring to mid-summer, some of them surviving longer to have their second brood just before dying (12-13-mo life span). The life history pattern for males was not as clear as for females owing to the successive merging of the newly-recruited individuals into the older ones with smaller asymptote body sizes. The center of distribution of the population along the elevation gradient on the sand flat was generally located around the MLWS level, with the breeding components mostly concentrated there. Most probably part of the overwintering population migrates to the subtidal zone to avoid the harsh conditions of the winter months.

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A new species of rhizocephalan, Sacculina polygenea, is described and illustrated on basis of material from the Amakusa Islands, Kyushu, Japan. Although previously recorded as a locally common parasite of the littoral crab Hemigrapsus sanguineus (de Haan, 1835), it has remained undescribed. The species is compared with S. senta Boschma, 1933 and S. nigra Shiino, 1943, which parasitize the same crab. Up to 5 concentric cuticular rings surround the stalk and adjacent part of the body. Such rings have never before been observed in any species of the genus and are probably evidence that S. polygenea moults its outer cuticle up to 5 times.

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The population structure, relative growth and reproduction of the fiddler crab, Uca arcuata (De Haan) were studied at Ohno River, Central Kyushu, Japan. The minimum size of ovigerous crabs was 19.4 mm CW. The largest size was 36.8 mm CW in males and 33.6 mm CW in females. Three and a half year rearing was conducted in the laboratory. Newly settled crabs grow to 19 mm CW by the end of next year, but females deposit eggs in the following year. The crabs reared in the laboratory grew to a maximum size of 32.5 mm CW in males and 29.3 mm CW in females. The size distribution and the results of rearing suggest that U. arcuata survives more than five years. Males were predominant in number; sex ratio was 1.36:1.00. Ovigerous females appeared from the last third of May to the last third of August. It is likely that females deposit eggs two or more times during the reproductive period. The relationship between egg number (Y) and crab size (X) is: Y=5721.4X-93702. Ovigerous females feed on the surface. There is an inverse relationship between the gonad and hepatopancreas indices suggesting that substances are shifted from the hepatopancreas to the ovary. The percentage of the large cheliped to total body weight increased with the crab size, reaching 40%.

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The morphological modifications caused by Sacculina polygenea in the grapsid crab Hemigrapsus sanguineus were examined. Parasitized males carrying externa were divided into seven stages of feminization by the degree of reduction of the first and second pleopods and the appearance of biramous pleopods on the third to fifth abdominal segments. All males examined retained first pleopods and most of them were Stage I or II. The development of femaletype biramous pleopods rarely occurs. Only 10.1% crabs were in advanced stages of feminization. Enlargement of the abdomen and reduction of chela height in parasitized males were pro nounced in small males and less so in larger males. Modification caused by the rhizocephalan parasite likely proceeds from when the host is young and small.

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Predator-prey interactions between the portunid crab, Scylla serrata, and the grapsid crab, Hemigrapsus penicillatus, were investigated under laboratory conditions. Three trophic relationships were found: firstly, S. serrata preyed on H. penicillatus, secondly, H. penicillatus preyed on S. serrata, and thirdly that no trophic interactions occurred. Variation in the outcome of these interactions can be explained by crab size (including cheliped size) and size selective behaviour of the two species.

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Manipulation of the host's behavior by the rhizocephalan parasite, Sacculina polygenea, was observed in an aquarium with a video camera. The brachyuran host, Hemigrapsus sanguineus, cleaned the surface of the parasite's externa with its chelipeds. When the parasite released nauplii, the host assisted the parasite by adopting the stereotypic larval release behavior of female crabs. While releasing the nauplii, the host remained stationary on a rock, occasionally flexing its abdomen with a waving action. After releasing nauplii several times, the externa became smaller and withered, and the host removed it with its chelipeds and ate it. This behavior was displayed by both sexes of the host.

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Field trials were conducted to examine the feasibility of guiding juvenile freshwater shrimps to fishways using lights at nighttime during the summer. The number of migrating shrimps was counted after different numbers and arrangements of underwater electric torches (wavelength 400-700 nm, narrow focus) were illuminated in the rivers. An underwater beam (2400-15000 lx) placed on the bottom and directed diagonally upstream across the river induced shrimps (e.g., Caridina japonica, C. leucosticta, C. typus, and Macrobrachium formosense) that were migrating along one bank to move across to the other side.

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