The oxygen consumption of Nephrops norvegicus animals collected from the upper continental slope (400 m depth) in the northwestern Mediterranean was monitored under constant conditions of darkness and temperature. Two experiments were performed starting at the beginning of the expected day and at the beginning of the expected night phases, respectively. Mean oxygen consumption values recorded during the expected night were significantly higher than those recorded during the expected day. The slopes of the time series of oxygen consumption data of the two experiments were recalculated in consecutive 1-h intervals, being then averaged for corresponding 1-h time intervals. The plotting over a 24-h cycle of these mean hourly-values revealed a global nocturnal increase in the oxygen consumption in the laboratory. This result is discussed and compared with previously reported catch patterns accounting for emergence from burrows in the field, and locomotor and cardiac activity rhythms recorded in constant conditions in the laboratory in animals from the same depth.

The external morphology of the cypris larva of the epibiotic barnacle Octolasmis californiana Newman, 1960, found on the gills of the portunid crab Callinectes arcuatus Ordway, 1863, from Nayarit, Mexico, is described for the first time. The cyprid is elongated, about 550 μm in length; the surface of the carapace exhibits scattered pores and short setae, with prominent frontal horn pores and five pairs of lattice organs. The arrangement of the lattice organs is different from previously reported patterns. The first pair of thoracopods is slightly different from the rest, for the endopod bears five setae and the exopod six, whereas thoracopods 2–6 bear six setae on the endopod and seven on the exopod. The external morphology of the cyprid of O. californiana combines derived characters, such as the type of lattice organs, with others that might be regarded as plesiomorphic, such as the setation pattern of the thoracopods.

Intrinsic musculature of the fifth and sixth limbs of selected halocyprid ostracodes is used to identify the basis and, also, bristles that could be interpreted to represent an exopod. It is concluded that, in general, species of the Halocyprida bear bristles that could be interpreted to represent an exopod. Taxa that bear an unsegmented exopod lobe on the sixth limb are restricted to the deep sea and anchialine caves, and this suggests their antiquity.

The tanaidaceans collected by submersible from a deep-sea cold-seep site in the Gulf of Mexico were examined. Three new genera and four new species are described. Species belonging to the genera Coalecerotanais new genus, Bathyleptochelia new genus, Crurispina new genus, Araphura, and Paranarthrura were identified. The tanaidacean fauna of this cold seep was composed of several evolutionary lines of both shallow-water and deep-water origin. Mouthpart dissimilarity suggests that several different feeding strategies are employed.

The paguroid-infesting bopyrid genera Anathelges Bonnier, 1900, and Stegophryxus Thompson, 1902, are found to be synonymous. Three species formerly placed in either Anathelges or Stegophryxus are not congeneric with Bopyrus resupinatus, the type species of Anathelges. A new monotypic genus Falsanathelges is erected for Anathelges muelleri Nierstrasz and Brender à Brandis, which is redescribed based on type and additional material. A second new genus, Minimathelges, is erected for Stegophryxus minutus Markham and M. nanus n. sp. from the Loyalty Islands. Anathelges mossambica Barnard is provisionally transferred to Pseudostegias Shiino, based on examination of the damaged lectotype. Additionally, the genus Metathelges Nierstrasz and Brender à Brandis is transferred from the Athelginae to the Ioninae based on examination of the holotype. A key is provided for all eight athelgine genera.

The spermatozoal ultrastructure was investigated in male penaeid shrimp Artemesia longinaris from Mar del Plata (Buenos Aires Province, Argentina) fishing grounds. The spermatozoon of A. longinaris is a typical dendrobranchiate sperm, basically consisting of a subspheroidal main body and a long spike. The complex acrosomal structure is comprised of the acrosomal vesicle, formed by the acrosomal cap and spike, and the subacrosomal substance. A central, rounded protuberance arises from the concave side of the cap opposite the spike. As inferred from longitudinal and transverse sections, the spike is filled with densely packed longitudinal filaments, which are coiled and form a loose helix. The occurrence of an apomorphic protuberance at the base of the acrosomal cap in A. longinaris, Parapenaeus longirostris, and Penaeopsis serrata justifies the grouping of these three genera into the tribe Parapeneini. The filamentous inner structure of the spike appears to indicate a closer proximity between A. longinaris and P. serrata than between either of them and Parapenaeus longirostris.

Growth and survival of Penaeus semisulcatus larvae were measured in factorial combinations of temperature (20°, 23°, 26°, 29°, and 32°C) and salinity (28‰, 29‰, 32‰, 34‰, and 37‰). Three experiments were maintained for 5 to 6 d, between late nauplius and first mysis stages. Salinity did not have a significant effect on growth or survival above 28‰. At 28‰, both growth rate and survival decreased (although the reduced survival occurred only at the lowest temperatures). While temperature had a substantial and regular influence on growth rate (larvae growing more rapidly at warmer temperatures), the effect on survival was not clear. In one experiment, there was significantly lower survival at the higher temperatures (32° and 29°C); however, temperature did not affect larval survival at all in the other two experiments. The results were compared with six years of published data on temperatures and salinities in Albatross Bay, Gulf of Carpentaria, Australia, and indicate that naturally occurring salinities are unlikely to directly affect survival of P. semisulcatus larvae in that area. Summer temperatures regularly exceed 29°C, raising the possibility (from the results of one experiment of three) that high temperatures may cause larval mortality in Albatross Bay. However, other published evidence indicates that such an effect is unlikely to have practical significance.

Reproduction and population dynamics of Acetes chinensis were studied on the western coastal areas of Korea, Yellow Sea, between May 2000 and October 2001. Female maturity was determined from the ratios of females with maturing ovaries by size. The size at which 50% of females are mature is estimated as 8.96 mm carapace length. The mature females first appeared in April, reached a peak in July, and then did not appear after September. The main breeding season (percentage of females with mature ovaries greater than 50%) was from July to September. Similar pattern could be found in monthly changes of gonad index (GI), showing relatively higher GI during the annual breeding season. Mean gonad index examined weekly during the breeding season (June–September) peaked both in the middle of June and early September. Parameters of growth were estimated using the modified von Bertalanffy growth function (VBGF) model incorporating seasonal variation in growth. Females grew faster and reached a larger size at age than males (L_∞ = 13.51 mm CL and K = 0.69 yr⁻¹ for females, and L_∞ = 10.48 mm CL and K = 0.84 yr⁻¹ for males). The mortality rate (Z) (± 95% confidence limit) calculated by length-converted catch curves was estimated as 3.93 (± 2.00) yr⁻¹. The structure of the recruitment patterns obtained by the ELEFAN program indicated two normally distributed groups. The estimated longevity was 0.75–1.0 yr for the summer generation and 0.58–0.83 yr for the winter generation.

Herein, we detail several important life-history parameters of the banded coral shrimp, Stenopus hispidus, a popular marine ornamental shrimp. Among the life history parameters described are 1) size at settlement, 2) molt interval, 3) post-settlement mortality and movement, 4) growth, and 5) relative fecundity. Overall, we document the effects of body size on several life-history parameters. Molt interval increased and growth increments declined as shrimp body size increased. Furthermore, mortality was size-specific in S. hispidus; large individuals had higher survival rates than smaller individuals. We also show that variation in size at settlement of S. hispidus in the upper Florida Keys, U.S.A., was much smaller than that found in previous studies from other parts of the world. Based on field measures of size at settlement, molting probability, and growth increment per molt, we developed a crustacean growth model, which included discontinuous growth and natural variability in the parameters. With it, we describe expected patterns of growth and post-settlement age for S. hispidus in the upper Florida Keys. Finally, we document positive relationships among female body size, egg mass volume, and egg number.

The ratio of sexually active males to fertilizable females (operational sex ratio, OSR) is the most important parameter determining the direction and intensity of sexual selection. It is widely accepted that the pronounced sexual dimorphism featured by many crustaceans is a consequence of a strongly male-biased OSR. Many studies have contributed to the understanding of function and origin of sexually selected traits, but few attempts have been made to measure the OSR. Using the rock shrimp Rhynchocinetes typus as an example, herein we propose a relatively simple method to assess the OSR of natural populations of crustaceans, as follows. The number of individuals willing to mate was estimated by the study of both the population structure (field sampling) and the readiness to mate (laboratory experiments). Field sampling showed that adult sex ratio was balanced during most seasons and that early ontogenetic male stages dominated among the males. Laboratory experiments demonstrated that females became receptive asynchronously, and that males from early ontogenetic stages showed limited readiness to mate. Based on this information, we estimated the OSR under three different scenarios. The results indicate that the OSR is highly male-biased in R. typus even in the more conservative scenario supporting the original predictions. Most male mate-competitors are early ontogenetic stages, whereas few are late stages. The results demonstrate the importance of estimating the OSR individually for shrimp categories differing primarily by sex and subsequently by individual conditions (ontogenetic stage, molt stage), which affects the probability of a potential mate to be sexually active. We suggest that this approach provides important information necessary for a better understanding of crustacean mating systems.

Some reproductive features of Macrobrachium potiuna and M. olfersi females were compared, correlating brood pouch volume with the number and volume of eggs during the incubation period. These data contribute to the understanding of the diversity of reproductive strategies observed in the family Palaemonidae. Macrobrachium olfersi and M. potiuna were collected in Ratones basin, Santa Catarina Island, Brazil, and the total lengths of the ovigerous females were determined in the laboratory. The eggs were measured, and the individual fecundity was determined. Volume of the eggs, egg mass volume, and brood pouch volume were estimated. Females of M. potiuna had a mean body length of 34.9 mm, mean brood pouch volume of 71.3 mm³, mean fecundity of 35 eggs, and egg mass volume of 70.3 mm³. Macrobrachium olfersi females had a mean body length of 46.7 mm, mean brood pouch volume of 127.9 mm³, mean fecundity of 1917.2 eggs, and egg mass volume of 96.6 mm³. Differences of fecundity and egg volume in M. potiuna and M. olfersi indicate the adoption of different reproduction strategies. However, proportional egg loss and increase of egg volume during the embryogenesis reflect particularities of the reproductive process of the females in the Palaemonidae.

Macrobrachium olfersi is a palaemonid prawn with a broad geographical distribution, from the East Coast of the United States to southern Brazil. This paper attempts to establish the embryonic stages for M. olfersi based on morphological features in living and fixed embryos. We adopted nonfixed percentages related to the morphological events to define ten embryonic stages: pre-cleavage, cleavage, gastrula, germinal disk, naupliar, caudal papilla, C-shape, eye-pigmentation, segmented-abdomen, and pre-hatching. We hope the description of these stages can be used as a tool for studies of the embryonic process in species of Macrobrachium, and also as a guide to judge the developmental stages of palaemonids in environmental and experimental studies.

Instances of mutualism and commensalism between alpheid shrimp and other marine invertebrates and fish are common in tropical waters. In this study, we present evidence that the temperate alpheid big-clawed snapping shrimp (Alpheus heterochaelis) participates in a symbiosis with the black-clawed mud crab (Panopeus herbstii), which constructs and maintains burrows in salt marshes of mid-Atlantic states, U.S.A. We surveyed eight mid-Atlantic salt marshes and found that 11% of occupied crab burrows (n = 1042) also housed Alpheus. Feeding trials showed that whereas Panopeus readily consumes other marsh Crustacea (i.e., grass shrimp and fiddler crabs), it will not prey on snapping shrimp. Alpheus caged in the marsh without access to mud crab lairs could not construct burrows. These results suggest that alpheid shrimps, thought to be limited in distribution to unvegetated mudflats and oyster reefs, may expand their intertidal range by living commensally with Panopeus herbstii in salt marsh habitats.

A new genus and new species of pandalid shrimp, Calipandalus elachys, is described on the basis of the specimens from Taiwan, Solomon Islands, and New Caledonia in the western Pacific Ocean. Calipandalus new genus resembles Bitias Fransen, 1990, in the lack of an exopod on the third maxilliped, the short rostrum, and the presence of arthrobranchs on the four anterior pereopods. It is distinguished from Bitias by the presence of tegumental scales, the moderately spaced, fixed dorsal teeth on the rostrum proper, the short antennular stylocerite, and the peculiar structures of the mandibular palp and the chela of the second pereopod. The new species also bears similarity to particular species of Plesionika Bate, 1888, although the absence of an exopod on the third maxilliped sets the new species apart from Plesionika.

A new index was used to describe and quantify claw asymmetry for American lobsters, Homarus americanus. Length : width (L:W) ratios were calculated for each claw, and a measure of claw asymmetry (C_a) was computed as the percent reduction in the claw with the smaller L:W ratio. Fourth stage (first benthic stage) lobsters had relatively symmetrical claws, with L:W ratios of 4.3 in the cutter and 4.1 in the crusher claw, and a corresponding C_a value of 5.4%. Hatchery animals that could not differentially exercise one claw maintained a low average C_a value (2.5%). In adult animals, the L:W ratio decreased to a minimum of 2.7 for cutter claws, and 2.0 for crusher claws, giving a C_a value of 25.9%. This method was then used to assess claw development in animals exposed to one of four different natural substrates (cobble, shell, sand, and plant) in a hatchery setting. The development of claw asymmetry is known to be a function of increased exercise in one claw, and substrates allowing for more exercise should exhibit faster, greater asymmetry. It was observed that the overall morphology of claws changes greatly between the sixth and seventh stage. Although no treatment differences were observed at the sixth stage, by the seventh stage, animals subjected to shell substrate yielded significantly more asymmetrical claws. Thus, where lobsters settle can have a dramatic impact on the rate of development of claw asymmetry with potential fitness consequences.

Intra- and inter-specific competition for shelter, in relation to prior residence, sex differences, and body-size effects, was studied in the laboratory to assess the potential impact of the alien crayfish species Pacifastacus leniusculus on the endangered Japanese endemic crayfish species Cambaroides japonicus. The resident was placed in an aquarium, which contained a single shelter of preferred size for both C. japonicus and P. leniusculus. After 24 h, the intruder was introduced into the aquarium. In the experiments using different sex pairs of crayfish of approximately equal size, male residents had a significant prior residence effect against female intruders in both crayfish species in the intraspecific contests. However, residents of P. leniusculus dominated C. japonicus regardless of the sex in interspecific contests. In experiments using male crayfish pairs of different sizes, larger individuals had more successful possessions of the shelter against smaller individuals regardless of crayfish species. The body-size advantage strongly influenced the outcome of the both intra- and inter-specific contests regardless of residents or intruders and overcame the prior residence effect in both species. These results suggest that P. leniusculus is superior to C. japonicus in shelter competition if P. leniusculus invades the habitat of C. japonicus.

Commercial and recreational catches of the blue swimmer crab Portunus pelagicus in Cockburn Sound, a large marine embayment on the west coast of Australia, have risen markedly over the last 20–30 years. However, because commercial fishers changed from using tangle nets to traps to catch crabs during this period, the annual catch per unit effort data for the commercial fishery throughout this period are not directly comparable and cannot thus be used to elucidate whether the increased catches reflected an increase in crab density. Trawling was thus undertaken to estimate the densities of P. pelagicus in Cockburn Sound in the late 1990s to facilitate comparisons with those we estimated from trawl catch rates for this species in that embayment during the early 1970s. The comparisons demonstrate that, despite increases in commercial and recreational crab catches, the densities of P. pelagicus in Cockburn Sound have risen markedly between the above two periods. This change is probably related to a decline in the abundance of the large piscivorous predators of P. pelagicus as a result of heavy fishing pressure and possibly also to an increase in the abundance of the prey of this portunid. Size composition data demonstrate that appreciable numbers of crabs survived in Cockburn Sound until the end of their second year of life and even beyond during the early 1970s, whereas the vast majority of 1 crabs were removed by heavy fishing pressure by the month (June) that they had reached 18 months in age in the late 1990s. The fact that, in the late 1990s, few legal-sized crabs still remained for fishing between July and December and the 0 age class increased in number and size throughout the year accounts for the broad estimates of biomass becoming far greater in these months in the 1990s than in the corresponding months in the early 1970s. Growth during the first eleven months of life, i.e., in the period leading up to the age at which crabs reach the minimum legal size for retention, was significantly faster in the early 1970s than in the late 1990s when crab densities were much greater. The slower growth rate and the reduced longevity through heavy fishing pressure in the latter period would help account for females becoming mature at a smaller size and for ovigerous females being represented by one rather than two substantial size cohorts, respectively. The essentially single size cohort in the late 1990s and first cohort in the early 1970s correspond mainly to crabs in their first maturity instar, whereas the second cohort in the early 1970s predominantly represented crabs in their second maturity instar.

The panopeid mud crab Panopeus meridionalis is known to inhabit the intertidal zone of the estuarine temperate waters of the southwestern Atlantic, from Montevideo, Uruguay, to Mar del Plata, Argentina. The complete larval development of this species is described from laboratory-reared material and compared with known larvae of Panopeus.

The genetic structure of the common Cape river crab Potamonautes perlatus (Decapoda: Potamonautidae) was assessed among 21 populations from major drainage systems in South Africa using allozymes and sequence data from two mitochondrial genes (16S rRNA and COI). Protein gel electrophoresis of 15 loci encoding 11 enzyme systems revealed limited genetic variation in the Berg and Olifants drainages. However, in the Gamtoos and Breë river systems, and over all populations, moderate levels of variation were evident from the F_ST values. Gene-flow estimates revealed high levels of dispersal within and between drainages. In contrast, phylogenetic analysis of the 16S rRNA mtDNA sequence data from 10 representative populations revealed two distinct clades. One consisted of all the rivers that drain the western escarpment, and another consisted of rivers that drain the southern escarpment. The COI mtDNA and a combined sequence data analysis consistently placed the western flowing rivers in a distinct clade. The split into two clades coincided with the western and southern drainages with the Cape Fold mountains being the barrier that separates the drainage basins. These results are discussed in light of possible geological factors that could have sculpted the present genetic patterns. Allozyme and sequence data were generally complementary at a small spatial scale (within drainages), where both markers indicated the absence of genetic structure. However, at larger spatial scales, the sequence data proved superior at detecting genetic variation.

Two new species and two new records of the family Camptandriidae are reported from mangroves in the southwest coast of Irian Jaya, Indonesia. Paracleistostoma laciniatum, new species, and P. quadratum, new species, differ from congeners in the form of the male first pleopod, which is long and cylindrical in the first species, and short and rounded in the second. Paracleistostoma mcneilli (Ward, 1933) and Baruna trigranulum (Dai and Song, 1986) are recorded for the first time from Indonesian waters.

The growing demand for highly priced marine ornamental species has contributed to the endangered status of coral reefs. A list of 128 of the most heavily traded marine ornamental decapod crustacean species is tabulated. The development of commercial culture techniques, the knowledge of the larval development, and the association with vertebrate and invertebrate organisms are presented for these species. Forty-nine of the species are caridean shrimp, with the Hippolytidae family alone accounting for 15. Anomuran and brachyuran crabs are the next most traded groups (32 and 27 species, respectively), with the pricey stenopodidean shrimp, Astacidea, and Palinura lobsters being represented by a considerably lower number of species (7, 7 and 6, respectively). The main bottlenecks impairing the commercial culture of ornamental shrimp and lobsters are their long larval development and poor survival rates. The main constraint for the development of culture techniques for hermit and brachyuran crabs is their low commercial value. The ecological impacts of harvesting ornamental species are still poorly studied. Nevertheless, the collection in considerable numbers of hermit and small majid crabs (e.g., Clibanarius and Mithraculus) from tidal areas, fish cleaning shrimp (e.g., Lysmata and Stenopus), and the crown-of-thorns sea star eaters Hymenocera, is likely to have serious impacts on the ecosystem. The cooperation between researchers working on larval biology, population dynamics, ecology, aquaculture, and fisheries is essential to properly manage the collection of marine ornamental decapods.