Tegumental glands are a ubiquitous feature of the decapod cuticle. In the fifth pair of pereiopods (P5) of Aegla platensis Schmitt, 1942, these tegumental glands (PeTG's) are similar to those described in other decapod crustaceans. Type 1 PeTG's, with mucous and serous cells and type 2 PeTG's, with serous cells only are organized into proximal, medial and distal clusters along the appendage. Both types of PeTG's possess secretory cells arranged concentrically around a central duct. These secretory cells have well developed Rough endoplasmic reticulum (RER) and numerous Golgi Complexes, and possess electron-lucid and electron dense vesicles. The finely granular aspect of the electron-lucid vesicles suggest they contain a mucous-like substance, while electron-dense vesicles probably contain a substance of a proteinaceous nature. Despite various hypotheses, there are few indications that these substances act as cleaning agents. However, the cytoplasm of the secretory cells appear to be composed of concentric lamellas that could be responsible for the production of surfactants (cleaning substances). In the Anomura, P5 is involved in grooming but there presently is insufficient evidence to show that the glands play a role in this process.

We observed in the laboratory the behavior of six individuals of an as yet undescribed species of Speleonectes (Remipedia) over a period of 76 days. The live specimens were collected from an anchialine cave on the Yucatan Peninsula and maintained in separate aquaria at the Zoological Museum Amsterdam. In addition, field observations were conducted in the same cave to compare the laboratory results with naturally occurring behaviors. We found a variety of complex behavioral traits that include several new and unexpected findings. For example, our observations suggest that remipedes are not obligatory, but rather facultative carnivores, and that filtering particles might be the predominant mode of feeding. A digital video with examples of various behavioral traits can be downloaded at  http://www.tiho-hannover.de/einricht/botanik/research.htm.

Feeding behavior of barnacles may be determined by various factors such as water flow direction, flow velocity, type and location of substratum, predators, systematics, and more. In this study, two shallow-water barnacles from the Red Sea, Amphibalanus (= Balanus) amphitrite and Tetraclita rufotincta, and one from the Mediterranean, Perforatus (= Balanus) perforatus, were examined. Four feeding behavioral parameters were tested under changing conditions of flow direction: cirral fan turning angle, beat duration, beat rate, and percentage of time spent collecting food. When exposed to water, Tetraclita and Amphibalanus collected food vigorously and continuously, regardless of flow direction, while Perforatus perforatus spent far less time and effort collecting food. The differences in feeding behavior may indicate that food is more abundant for the Mediterranean barnacle than it is for the two Red Sea species. The nocturnal behavior of Tetraclita can be attributed to the higher abundance of food particles at night, and/or a diminished risk of predation at night.

Population structure and reproductive maturity of females were investigated in the shrimp Artemesia longinaris Bate, 1888 from coastal waters of northern São Paulo State (Brazil, 23°S) and Mar del Plata (Argentina, 38°S) from June 2001 to May 2002. Monthly collections were taken by commercial shrimp fishing boats equipped with bottom trawl nets. Population parameters from size frequency distributions and size (carapace length = CL) of female reproductive maturity were analyzed and compared from the two sampling areas. Latitudinal trends in reproductive parameters of A. longinaris were shown in overall body size and size of reproductive maturity, both of which were smaller in females from the tropical location than those from the cold-temperate sampling area. Largest females (> 30 mm CL) were collected in Argentina, while Brazilian specimens reached maximum size at 27 mm CL. The smallest size of female sexual maturity was estimated at 13.6 mm CL in Brazilian samples compared to 22.1 mm CL calculated for those from Argentina. Populations from both regions exhibited a bimodal size distribution in the spring, with the peak at small body size probably corresponding to recent recruits and the peak at larger body size to reproductive females or shrimps migrating in from deeper waters or other latitudinal regions. In late spring and summer, an intrusion of the cold South Atlantic Coastal Water mass was observed which lowered water temperature and stimulated plankton production, the primary food source for the larvae of a typically cold-temperate species such as A. longinaris. The trend of increasing body size and delay of sexual maturity with increasing latitude appears to be correlated with the decreasing water temperature and increasing plankton productivity at higher latitudes.

The Schumacher-Eschmeyer and the Schnabel estimators for closed population were employed to estimate the population size of Aegla franca from an isolated section (30 m long; area: 76.125 m²) of the Barro Preto stream (20°18′47″S; 47°16′37″W) in the summer and winter seasons of the year 2005. These methods involve mark-recapture technique with multiple sampling, and each season estimate was conducted for eight consecutive days. The study area was isolated with a 4 mm mesh net to prevent migration of aeglids into or out of the study area. Traps were randomly set overnight and inspected for captured aeglids in the following morning. Two marking techniques were employed separately: a mixture of silver purpurin powder and fast-drying glue gel (summer estimate) and cauterization by red-hot pin head (winter estimate). All unmarked individuals from each sampling event were sexed, had their carapace length measured and were then marked, and released back in midpoint of the isolated area of the stream along with previously marked (recaptured) specimens. The Schumacher-Eschmeyer estimator provided very close results between the summer (N = 212 and density = 2.8 ind./m²) and the winter (N = 218 and density = 2.9 ind./m²) estimates. The Schnabel estimate results were also very similar to that obtained by the Schumacher-Eschmeyer method for each corresponding season of the year. Regardless of the marking technique employed, the results obtained and field observations from each estimate indicate that none of the assumptions required by both methods were violated. After subtracting the percentage of immature specimens, the projected overall population size of mature Aegla franca for the whole extension of Barro Preto stream varied from approximately 33,200 in the summer and 29,500 adults in the winter (Schumacher-Eschmeyer estimator) for an estimated area of occupancy equivalent to 0.0125 km².

Sand fiddler crabs, Uca pugilator, from North Carolina (NC) are two-times smaller than ones from Florida (FL). A water balance study was conducted to examine this size difference in relation to possible changes in habitat suitability. Like most crabs, U. pugilator are classified as hydrophilic, which is consistent with their preference for humid environments. In contrast to the North Carolina population, U. pugilator-FL loses water less rapidly and has higher percentage body water content, a water balance strategy that emphasizes retention. Conversely, the amount of body water required is less for U. pugilator-NC, enabling it to maintain water balance despite having a higher water loss rate. Both tolerated only about 1/4 loss of body water before succumbing to desiccation. Neither experienced a critical transition temperature, CTT. We concluded that water balance profiles of these two populations are complementary, representing trade-offs that permit survival in a moisture-rich habitat. Lower body water content, however, overlaps with features of arthropods that thrive at low temperature, suggesting that U. pugilator-NC may be more cold tolerant.

The effects of preventing female helmet crabs, Telmessus cheiragonus from mating during one breeding season on egg production and egg viability were assessed by investigating the egg clutches of the females isolated from males. A total of 38 females and 18 males were collected in April before the mating peak in 1996 and 1997 in the sublittoral zones of Usujiri, southern Hokkaido, Japan. Eighteen females were held together with 18 males (mating group) and 20 females were isolated from males (non-mating group) during about 7 months of captivity. Subsequently, 11 females of the mating group molted, copulated and produced an egg clutch, and 10 females of the non-mating group molted and spawned without mating. Egg clutch weight and egg diameter did not differ significantly between these two groups. There was also no significant difference in the percentage of viable eggs in an egg clutch between the groups. These results show that preventing female T. cheiragonous from mating during one breeding season has no effect on either clutch size or % viable eggs in a clutch. Sperm storage over one mating season in this species may be advantageous because it allows multiparous females, especially larger ones which could molt and copulate less frequently, to ensure their eggs will be fertilized.

Little is known about sperm allocation patterns in crustaceans, especially in anomuran crabs. We investigated whether male stone crabs, Hapalogaster dentata, change the number of ejaculated sperm depending on risk of sperm competition, and whether the pattern of sperm allocation to females of different body size varies with male body sizes in laboratory experiments where the male:female sex ratio (SR) and body size of both sexes in mating pairs were controlled. The number of ejaculated sperm differed significantly between matings under SR of 1:1 and 2:1, and males showed an increase in number of ejaculated sperm in the presence of a potential rival male. These results suggest that sperm competition may occur in the stone crab, and superiority in number of ejaculated sperm relative to rival males would be important for increasing male reproductive success in this species. Larger males showed a significant increase in the number of ejaculated sperm with increasing female size, while smaller males did not. The size of the ejaculate passed to larger females by smaller males was significantly reduced, resulting in low fertilization rates of larger females. The ability of males to provide sufficient sperm for fertilization may be one factor resulting in preference of female stone crabs for larger males.

We investigated geographic variation in size and stage (instar) at maturity of snow crab (Chionoecetes opilio) on the eastern Bering Sea shelf. Size-frequency distribution analysis showed that females can reach maturity at four different instars, presumably Instars VIII to XI. Geographic variation in instar structure generates clinal variation in size at maturity, from small size at high latitudes (colder) to large size at low latitudes (warmer). Different pieces of evidence support the hypothesis that geographic variation in mature female size is a phenotypic response to environmental conditions governed by a single reaction norm. Clinal variation conforms to the “inverse Bergmann's rule”. We argue that a single macroecological rule should not be expected to explain all latitudinal size gradients observed in marine invertebrates. Size at maturity fluctuated cyclically, and was negatively and significantly cross-correlated with strength in the recruitment of females to the mature population. Cycles in the latter were manifested as four commensurate and regularly spaced pulses over the last three decades. Mechanisms that may underlay this intriguing phenomenon, including density-dependent growth rate, require further scrutiny.

Approximately 65% of Tasmania's southern rock lobster Jasus edwardsii catch is taken from the west coast. Fishers from the west coast have reported that many inshore sites that were productive 10 or 15 years ago are no longer productive so that they now receive reduced effort, with effort displaced into other regions. The failure of stocks to recover in these sites despite widespread increase in biomass in the Tasmanian fishery overall suggests that recruitment to the inshore west may be low. This was investigated from puerulus catch monitoring, which has been conducted using crevice collectors at 28 sites around the Tasmanian coast at various periods. Catches at the 8 sites off the west coast (0.24 ± 0.06 mean pueruli per collector per month) have been consistently lower than those from the 18 sites off eastern Tasmania (1.68 ± 0.12 mean pueruli per collector per month). This spatial pattern supports the hypothesis that low recruitment to inshore west coast areas results in a population that is not robust to fishing pressure. Regional differences in recruitment point to the need to incorporate spatial components into management of rock lobsters.

The complete larval development of the sesarmid crabs Pseudosesarma bocourti (A. Milne-Edwards, 1869) and P. moeschii (de Man, 1892) was obtained through laboratory culture. The previously unknown larval stages of both species, consisting of four zoeal stages and a megalopa, are morphologically almost identical and thus described and illustrated as one.The morphology of the zoeae and megalopae is similar to that known from other species of Sesarmidae, but zoeal stages of three species of Pseudosesarma can be differentiated from other known larvae of sesarmids by the presence of the very long curved posterolateral processes on pleomere 5. While zoeal stages of P. bocourti and P. moeschi are morphologically very similar, the megalopae of both species can be easily distinguished by the setation on the uropod (1,5 in P. moeschii versus 1,6 in P. bocourti).

With intensified harvesting and environment deterioration during the past two decades, a rapid decline in the number of coconut crabs, Birgus latro, which is a protected species listed in the IUCN Invertebrate Red Data Book, has occurred on many islands. Thus, it is important to protect this species by establishing conservation areas and/or replenish natural population by larval cultivation. In this study, the development modes were analyzed and the effect of enriched diet on larval growth and survival were examined. Two types of zoeal development patterns were found. In general, zoeae took 29-33 days to complete five zoeal stages and metamorphose to glaucothoes. However, some zoeae directly metamorphosed from the 3rd zoeal to glaucothoe stage in 25∼28 days. Morphologically, these zoeae with accelerated development had thoracic appendages that appeared like the fifth stage zoeae, but with the telson, antennule, and antenna similar to those of the third stage zoeae. When fed Artemia nauplii enriched with nutritious substances, the zoeae had significantly greater survivorship and sizes, particularly at the fourth and fifth zoeal stages. Accelerated development may suggest early adaptation to a terrestrial lifestyle. The adaptation of larval development related to glaucothoe size and zoeal life span is also compared and discussed for eight terrestrial hermit crab species of Coenobitidae. The comparison suggests four adaptive modes of larval development and these are described as mangrove adaptation, larger glaucothoe adaptation, smaller glaucothoe adaptation, and hypersaline adaptation. The selective advantage of each mode may reflect a response to the uniqueness of each specific habitat.

To elucidate the osmoregulatory mechanisms underpinning the invasion of fresh water by the palaemonid Crustacea, we investigate the contribution of free amino acids (FAA) to intracellular isosmotic regulation in selected ontogenetic stages of two diadromous, neotropical shrimps, Macrobrachium amazonicum and M. olfersi, exposed to fresh water or to saline media. We also evaluate anisosmotic/ionic extracellular regulatory capability in adult M. amazonicum alone; all data for adult M. olfersi are from McNamara et al. (2004). Adult shrimps show similar osmotic and ionic regulatory capabilities, including elevated hemolymph osmolality in fresh water, moderate isosmotic points, hyper-regulatory capability up to 20‰, and good tolerance of saline media. However, the two species rely on brackish water to different degrees to complete their life cycles: while M. olfersi zoeae 1 and 2 survive well in fresh water, those of M. amazonicum die within two hours. Total FAA titers increase significantly over the ontogenetic sequence in both species, independently of salinity exposure, concentrations increasing sharply in M. amazonicum zoeae 1 alone, but steadily from embryos to adult M. olfersi. While total FAA titers increase significantly on transfer of zoeae 1 ( 43%) and adult (muscle 72%, gill 62%) M. amazonicum to elevated salinity (25‰), their effective contribution to hemolymph and intracellular osmolality is unaltered (≈16% in zoea 1, 6-8% in zoea 2 and adult tissues). Total FAA titers in M. olfersi increase in embryos ( 95%), zoeae 1 ( 23%) and post larvae ( 28%), and in adult tissues (muscle 69%, gill 110%, nerve 187%) after salinity exposure. However, effective contribution to intracellular osmolality increases only in embryos (5 to 6%) and adult nervous tissue (6 to 13%). In both species, total FAA increase is due to the most abundant non-essential FAA, glycine, alanine and proline, and arginine. Our analysis shows that diadromous species like M. amazonicum and M. olfersi exhibit lower total FAA titers compared to marine species. Such findings allow a better understanding of the physiological mechanisms underlying the invasion of fresh water by these recent colonizers.

Whether male Tanner crabs, Chionoecetes bairdi, undergo a terminal molt associated with a change in claw allometry has long been debated. We measured molting hormone levels in captured male C. bairdi to assess the potential for molting. We plotted a frequency histogram of chela height to carapace width ratios and found a bimodal distribution of crabs with a ratio of approximately 0.18 separating the two modes. Male crabs with a ratio less than 0.18 were classified as “small-clawed” (SC) while crabs with a ratio greater than 0.18 were classified as “large-clawed” (LC). Circulating molting hormones between SC and LC crabs were compared. Significantly lower ecdysteroid levels were found in LC crabs, indicating that this morphotype had negligible potential for molting. Circulating ecdysteroids were measured in SC males of different shell conditions (soft, new, old, and very old) and no significant differences were found. This research suggests that the molt to LC morphology is a terminal molt. The results from this study have important implications for fisheries management because sub-legal LC males will not recruit into the fishery and removal of larger males may have long term effects on population size structure.

Idotea balthica has long been studied for intraspecific variation at the phenotypic and ecological level. Recent work found deep genetic divergences among several regional populations of this species in the North Atlantic. Here we report development of microsatellite loci for Idotea and use these newly developed markers to evaluate population structure among the mitochondrial clades. We also provide a detailed morphological evaluation, including SEM description of relevant traits in one of the more divergent groups. Phenotypically, the examined clades do not differ significantly, though individuals from populations in Virginia (U.S.A.) have more setose pereiopods than European and other museum specimens. The preliminary microsatellite data presented here suggest that these markers should be of utility for a variety of small-scale ecological and behavioral analysis in some related Idotea species. Although microsatellites are inappropriate for species designations, there is significant differentiation among mitochondrial lineages indicating that nuclear loci may show similar differentiation as mtDNA among regions. Together the subtle morphological variation and microsatellite data suggest that additional nuclear gene sequencing and reproductive studies are warranted to determine the taxonomic status of these regional forms.

A new species of bioluminescent ostracode, Vargula annecohenae, from Belize is described on the basis of morphology and mating displays. At night, male V. annecohenae ostracodes produce an elaborate species-specific display in order to attract females. These displays occur as a series of rapid flashes in an upward direction, above shallow grassbeds.

Amurocrangonyx n. gen. is described on the basis of recently collected specimens of Crangonyx arsenjevi (Derzhavin, 1927), a very poorly known subterranean amphipod crustacean originally described from springs in the Khor River basin of the Ussury River drainage in the Russian Far East. The species is redescribed from specimens obtained from the type-locality, Orekhovy spring, and a neotype is designated. A careful examination of the newly acquired material, although closely similar morphologically to Crangonyx, suggests that it represents a new genus in Crangonyctidae. However, determination of the precise phylogeographic relationship of Amurocrangonyx to Crangonyx or to other crangonyctoid genera in East Asia is unclear and must await molecular analyses.

The taxonomy of the rare Macrophthalmus leptophthalmus (H. Milne Edwards, 1852) is reviewed. On the basis of distinctive features of the carapace, eyes, and epistome, M. leptophthalmus is assigned to the subgenus, Euplax H. Milne Edwards, 1852, new status, a taxon that has been incorrectly synonymised under Macrophthalmus (Venitus) Barnes, 1967. A related species, Macrophthalmus (Euplax) dagohoyi, new species, is described from subtidal mangroves in Bohol, central Philippines. Macrophthalmus (Euplax) dagohoyi can easily be distinguished from M. (Euplax) leptophthalmus by different carapace, cheliped, walking leg and sternal characters. A key to the genera and subgenera of Macrophthalmidae is also presented.

Several species of crabs from hydrothermal vent sites in the Pacific Ocean were found to be infested by small, symbiotic nemertean worms. Worms occurred on both male and female crabs, and were located in mucous sheaths adhering to the axillae between the limbs of males and females, the setae of the pleopods of females, and the sterna of infested male and female crabs. Only juvenile and regressed adult worms were observed, primarily because no ovigerous hosts were examined. Similar species of worms mature by eating eggs, then regress or die after host eclosion. Based on the size of the worms from the vent crabs, their habitus with their crustacean hosts, the presence of accessory stylet pouches, and the presence of a single stylet on a large basis (monostiliferous), we place the worms in the family Carcinonemertidae, within the genus Ovicides. Infestations were found on crabs from vent sites on the western Pacific back-arc basins, on the southern East Pacific Ridge, and on the Pacific-Antarctic Ridge, indicating a widespread distribution of the symbioses. This represents the first record of Carcinonemertidae from a deep-sea host, a new host family, Bythograeidae, for these symbionts, as well as the first record of parasitism on a deep-sea bythograeid crab.