The digestive system of first stage Argulus japonicus larvae is described following reconstruction from serial sections. The morphology of the digestive tract is similar to adult branchiurans. It consists of an esophagus, esophageal funnel, anterior midgut (crop), midgut diverticula, posterior midgut (intestine) and a hindgut. However, the epithelial cells lining the midgut of newly hatched larvae contain large amounts of yolk. The midgut diverticula are less ramified than in the adult and arise from the anterior midgut as two main arms which branch anteriorly and posteriorly into the carapace. The posterior midgut is lined with large swollen cuboidal epithelium with large vacuoles and a ciliated border, whereas the adult posterior midgut is lined by large papilliform cells. Argulus japonicus larvae survive a day after hatching without nutrition from a host. First stage larvae feed mainly on host epithelial cells and mucus. There was no blood observed in the lumen of the digestive system.

Male waving displays of the species of Ilyoplax (Brachyura: Ocypodidae) have so far been described in I. delsmani, I. gangetica, and I. orientalis. In this study, male waving displays of I. dentata, I. dentimerosa, I. deschampsi, I. formosensis, I. integra, I. ningpoensis, I. pingi, I. pusilla, I. serrata, I. strigicarpa, I. tansuiensis, and Ilyoplax sp. are described for the first time. Waving display of the above 15 species of Ilyoplax can be classified into three patterns; a circular type, vertical type, and asymmetrical type. Asymmetrical wave forms were observed in only two species, I. orientalis and I. tansuiensis, vertical wave forms were seen in four species, I. delsmani, I. dentimerosa, I. pingi, and I. serrata, while most other species exhibited circular wave forms. To understand the evolutionary divergence of these waving forms observed in species of Ilyoplax, a molecular phylogeny was reconstructed based on 1005-bp nucleotide sequences from mitochondrial 16S and 12S rRNA genes of 16 species and two out-group taxa. Phylogenetic analysis of waving forms suggested that circular waves evolved once in the early history of the lineage. Vertical wave forms were suggested to have subsequently evolved three times independently from circular wave forms, and the asymmetrical wave form has also evolved from circular wave form. The evolution of distinct waving forms is considered to be associated with the presence of geographic sympatric species.

The present study examined the effects of visual cues provided by a reflective environment on spontaneous behavior exhibited by crayfish (Procambarus clarkii) in an empty aquarium. The predominant components of spontaneous behavior were determined by observing the activity of solitary adult crayfish for 20 minutes in a glass aquarium containing fresh water and no objects. Five distinct behaviors were observed: rearing up (climbing on the wall), turning, cornering (facing the corner for 5 s or longer), backward walking, and crossing (crossing the midline of the aquarium). The frequencies of rearing up, cornering, and turning decreased when reflection from the glass wall was blocked with black cardboard or non-reflective plastic. In a tank containing mirrors on one side and non-reflective plastic on the other, crayfish cornered, reared up, and turned more in front of the mirrors. To examine whether or not such responses depend on socialization, crayfish were housed for two weeks either in same-sex pairs (socialized) or separately (isolated), and subsequently their behaviors were compared in a tank with mirrors on one side and non-reflective plastic on the other. Crayfish that had been housed in isolation showed no difference in rearing up, turning, cornering, or backward walking between the mirror and non-mirrored portions of the tank. Crayfish housed in pairs showed significantly more of all five behaviors in front of the mirrors than in the non-mirrored portions of the tank, and they spent significantly more time in front of the mirrors than in the non-mirrored part of the tank. On the other hand, isolated crayfish seemed to avoid the mirrored side. The results demonstrate that crayfish are sensitive to reflection, even the partial reflection present in an ordinary glass tank, and that responses of crayfish to a reflective environment depend on prior socialization.

Parasitization by sacculinids (Cirripedia: Rhizocephala: Sacculinidae) induces severe modifications in morphology, behavior, and reproduction of their host crabs. To understand the mechanisms involved, it is important to have comprehensive information on their association. However, such information has been poorly available, mainly because of scarcity of distinguishing characters of sacculinids hamper identification of them. In the course of the investigation of the associations using the molecular marker (COI gene) and morphological observation to identify sacculinids, three species of Sacculina, S. confragosa, S. imberbis, and S. yatsui, were found to parasitize a single host crab, Pachygrapsus crassipes, sympatrically in a restricted area. This is the first finding for three-on-one association in a single locality.

Puerulus and early juvenile stages of the spiny lobster Palinurus mauritanicus Gruvel, 1911 from the western Mediterranean are described and illustrated, and their morphological characteristics are compared with those described in other palinurids. This constitutes the first detailed morphological description of a puerulus of the genus Palinurus. The puerulus of P. mauritanicus presents a carapace already with some spines characteristic of the adult phase, which allows to differentiate it from the congeneric species Palinurus elephas (Fabricius, 1787) co-occurring in most of its distribution area. The puerulus of P. mauritanicus can be differentiated from those described for pueruli of the genera Panulirus and Jasus by the presence of very long, flagellated, and setose exopods on maxillipeds 2 and 3. The puerulus of P. mauritanicus resembles those described for Projasus by the presence of the crista dentata on the third maxilliped. The morphology and differential colouration of the early juvenile with respect to the adult are described.

Female blue king crab, Paralithodes platypus, were captured from the Pribilof Islands, Alaska, in July and October 2003 and shipped to the Kodiak Fisheries Research Center. Crabs were held in chilled seawater at 2, 3.5, or 4°C until hatching, and final counts were 4, 6, and 10 crabs in each treatment, respectively. Mean size of all crabs was 123.9 mm CL and did not differ significantly between treatments. Individual crabs required an average of 29 days for complete hatching, regardless of holding temperature. Earliest hatching began on or before 20 February 2004. Crabs captured in July and held at 4°C hatched significantly earlier, with a mean hatch date of 13 March 2004, than crabs captured in October and held at 2°C or 3.5°C, both of which groups hatched on a mean date of 18 April 2004. Crabs released an average of 416 ml of larvae, and 110,033 first stage zoeae. Excluding two crabs for which complete volumes were not obtained, there were no differences in volume or number of larvae released by crabs held at different temperatures. The pattern, duration and timing of larval release exhibited by blue king crab is similar to that observed for other lithodid crabs including red king crab (P. camtschaticus), golden king crab (Lithodes aequispinus), and southern king crab (L. santolla). Extended hatching periods for king crabs may be an adaptation to environmental variability and the uncertainty of adequate food sources for larvae, and represent a reproductive strategy of diversified bet-hedging.

The growing demands and high costs of commercial Artemia cysts and the establishment of new shrimp hatcheries and farms have caused people to search for local sources of Artemia, putting special attention on their nutritional characteristics. As an essential step to determine the biochemical composition of Artemia, the fatty acid profiles of decapsulated cysts from six tropical salterns of southern México [Campeche (1), Oaxaca (1), and Yucatán (4)], two of Cuba (Camagüey and Guantánamo), and from a temperate site (San Francisco Bay, USA) (SFB) were analysed using direct transesterification and gas chromatography-mass spectrometry. Of 51 fatty acids identified, C16:0 (hexadecanoic), C16:1 n5 (hexadecenoic), C18:1 n9 (octadecenoic), C18:1 n7 (octadecenoic), and C18:2 n6 (octadecadienoic) were the major compounds found. The SFB strain from a temperate area showed significant differences from the rest of the samples of tropical origin, having a greater concentration in the fatty acids 18:2 n5 (10, 13-octadecadienoic), 18:3 n3 (octadecatrienoic), and 18:4 n3 (6, 9, 12, 15-octadecatetraenoic). The SFB strain showed the lowest proportion of mono-unsaturated fatty acids. Based on the fatty acid composition, the Artemia strains studied can be assessed as “freshwater” type, except for the one from Oaxaca that had a “marine” type profile characterized by 3% to 4% of the fatty acid C20:5 n3 (eicosapentaenoic).

The export of cellular glucose depends on the endoplasmic reticulum bound enzyme glucose-6-phosphatase (G-6-Pase), which catalyzes the hydrolysis of glucose-6-phosphate to glucose-6, the final step required for the release of new glucose into the blood or hemolymph. The current study examined the effect of chloride on G-6-Pase activity in two marine crustaceans: the ion-regulating crab Menippe mercenaria, and the ion-conforming crab Libinia dubia. Elevated chloride (from 0 to 250 mmol L⁻¹ Cl⁻) stimulated hepatopancreas G-6-Pase activity in both crabs (2 times in M. mercenaria and up to 1.6 times in L. dubia). Elevated chloride also increased glucose export from isolated M. mercenaria hepatopancreas. These results are in stark contrast to G-6-Pase chloride inhibition previously reported in vertebrate liver. The sensitivity of G-6-Pase to changes in environmental chloride was determined in crabs acclimated to low (20‰) and high (45‰) salinity. M. mercenaria acclimated to high salinity became less sensitive to changes in chloride, G-6-Pase activity decreased by about half. Our results suggest that chloride may be an important regulator of gluconeogenesis in marine crustaceans and may help ensure adequate glucose release during times of high metabolic demand such as exposure to variable salinity.

Immunolocalization and ontogenetical changes in Na ,K -ATPase were investigated in the antennal glands, intestine, and branchial cavity in developing Homarus gammarus. The antennal glands lined by undifferentiated cells are detectable in embryos at stage EI 150 μm (EI: eye index; 640 μm at hatching). From a mesodermic sac and an ectodermic tubular epithelium (EI 225 μm), they develop into coelomosac, labyrinth, and bladder up to larval stage II. In larval stage III, the end parts of the labyrinth fold inward. In the first post-larvae, the coelomosac is completely enclosed in the folded labyrinth, there is no nephridial tubule. The definitive organization of the antennal gland found in adults is achieved in post-larval stage V. At EI 425 μm, the intestine epithelium is composed of cuboidal cells, and the branchial cavity is already formed at EI 325 μm. The presence of Na ,K -ATPase was detected on the basolateral side of ionocytes lining the epithelium sac of the antennal gland starting at EI 425 μm, in the intestine at EI 625 μm, and in the epipodites of the branchial cavity at EI 525 μm. In post-larvae (stage V), a strong fluorescence was also found on the inner-side of the branchiostegite epithelium. Thus the ontogeny of the osmoregulatory epithelia is completed only after metamorphosis and it conditions the occurrence of the adult pattern of osmoregulation.

Two new genera of crinoid-associated pontoniine shrimps, Brucecaris, new genus, and Unguicaris, new genus, are described and illustrated. Brucecaris is established for Periclimenes tenuis Bruce. Unguicaris panglaonis, new genus, new species, is described from crinoid-associated material collected at Panglao Island, Bohol Sea, The Philippines. Three species, Periclimenes alegrias Bruce, Periclimenes novacaledoniae Bruce and Periclimenes pilipes Bruce and Zmarzly, are transferred to Unguicaris since they significantly differ from the diagnosis of the type species of the genus Periclimenes Costa, P. amethysteus (Risso). Remarks on systematic positions of remaining crinoid-associated species of the genus Periclimenes are given.

We evaluated the usefulness of immersion in neutral red solution as a marking technique for studies of movement of the amphipod Corophium volutator. Amphipods were immersed for 20 minutes in solutions of neutral red at different concentrations (25, 50 and 100 mg L⁻¹). Amphipods incorporated dye at all concentrations, and the hepatopancreas remained distinctly stained red for at least 7 days. No increase in mortality was detected at any concentration when compared to a control treatment (0 mg L⁻¹). In a separate field experiment, staining did not significantly affect tendency of C. volutator to move. Overall, immersion in neutral red seems to be an appropriate technique to rapidly mark large numbers of C. volutator and is suitable for short-term mark-recapture experiments. This technique may also apply to other small-sized crustacean species with relatively transparent exoskeletons.

The International Conference and Workshop on Lobster Biology and Management (ICWL) has been convened about every third year for the past 30 years. The first was a small workshop with 37 participants from the USA and Australia. More recently, meetings have attracted about 200 participants. Although the focus of the meetings is broadly “biology,” the emphasis of each reflects both current hot topics and the major interests of the region where the meeting is being held. Recruitment issues dominated the first few, while mariculture and population assessments have been emphasized in the recent meetings. The impact of the meetings goes beyond communication of recent results. More than 300 peer-reviewed papers have been published in proceedings of the 7 meetings. A book resulting from the first meeting and proceedings from the second each have been cited more than 1000 times. Recommendations from workshops at the meetings frequently are followed, and collaborations appear to have sprung up. The ICWL clearly is a successful, and enduring, institution.

Beginning in the late 1980s, lobster (Homarus americanus) landings for the state of Maine and the Bay of Fundy increased to levels more than three times their previous 20-year means. Reduced predation may have permitted the expansion of lobsters into previously inhospitable territory, but we argue that in this region the spatial patterns of recruitment and the abundance of lobsters are substantially driven by events governing the earliest life history stages, including the abundance and distribution of planktonic stages and their initial settlement as Young-of-Year (YOY) lobsters. Settlement densities appear to be strongly driven by abundance of the pelagic postlarvae. Postlarvae and YOY show large-scale spatial patterns commensurate with coastal circulation, but also multi-year trends in abundance and abrupt shifts in abundance and spatial patterns that signal strong environmental forcing. The extent of the coastal shelf that defines the initial settlement grounds for lobsters is important to future population modeling. We address one part of this definition by examining patterns of settlement with depth, and discuss a modeling framework for the full life history of lobsters in the Gulf of Maine.

Ontogenetic changes in gregariousness by pre-reproductive animals, like that observed in juvenile Caribbean spiny lobsters (Panulirus argus), may be adaptive and reflect size-specific changes in the effectiveness of aggregation in promoting survival. Alternatively, aggregation may simply result from changes in the distribution or availability of suitable habitat structure, or from other behaviors that enhance survival. There are currently two hypotheses explaining the potential benefits of gregarious behavior in juvenile spiny lobsters, both of which focus on increasing survivorship by reducing predation pressure: the group benefit hypothesis and the guide hypothesis. The group benefit hypothesis argues that aggregations of juvenile lobsters reduce individual susceptibility to predators because groups are better able to fend off attackers or benefit by dilution of risk. The guide hypothesis suggests that aggregation is a consequence of shelter seeking behavior, in which individuals searching for shelter follow conspecific odors, thus reducing the time they spend in the open exposed to higher predation rates. The guide mechanism should be most effective in areas of low shelter density. We used an individual-based, spatially-explicit model describing recruitment of juvenile spiny lobster in the Florida Keys to compare behavioral models incorporating a guide effect and group benefit under conditions of high and low shelter densities. We found that the guide effect significantly enhanced survival only under the most extreme circumstances where shelter was scarce, the risk of predation highest, and the effective distance of the guide effect strongest. In contrast, small increases in direct group benefit led to significantly higher population abundances under a wide range of conditions.

The ability to culture larval lobsters is of paramount importance to the commercial development of effective aquaculture methods. Recently, we developed two separate laboratory culturing strategies that yielded the complete larval development from egg to puerulus (post-larva) for the commercially important and transpacific Pronghorn spiny lobster, Panulirus penicillatus (Olivier, 1791). Individual phyllosomal culture of 10 newly hatched animals was carried out in a static seawater system. Two of the 10 phyllosomata held at 24.5-26.0°C metamorphosed after 22 molts to the puerulus stage at 256 and 294 days respectively (final body lengths = 30.80 mm and 32.00 mm). Mass culture of 500 newly hatched phyllosomata was also carried out in two specialized acrylic flow-through seawater tanks. Of the 500 larval animals, 215 were randomly sampled and morphologically staged (10 distinct stages were observed and documented as well as two sub-stages). Seven phyllosomata that were mass cultured metamorphosed to the puerulus stage under a constant temperature regime of 24°C (mean days = 302.4 and mean final body length = 32.133 mm). This species is now one of eight palinurid lobsters and only the fourth Panulirus spp. to be cultured completely from hatch to settlement stage. The biological understanding of larval development for this species promotes the feasibility for aquaculture and potentially facilitates future modeling of larval dispersal and duration in the field.

The biology and fishery of the lobster, Palinurus elephas from the SW coast of Portugal was studied during two distinct periods 10 years apart in 1993-1994 (March 93 to March 94) and during 2003 (May to July). The landings at the port of Sagres, representing half of the catch of the country for this species, were sampled twice a week. The ovigerous season extends from September to March, with an individual incubation period of five months. Considering the ovigerous condition as an indicator of maturity in females, 50% of the females were mature at carapace length of 110 mm. Females below this size represent 95% of the population and account for 41% of the egg production. Females above 50% maturity, representing only 5% of the population, provide 59% of the eggs, showing the importance of larger individuals in the reproduction of this species. Most biological parameters estimated are within the range of values reported for this species in other areas with the exception that in our study the total length was smaller in relation to carapace length, so that females of a given carapace length carried fewer eggs. Parameters were estimated for the following relationships: total length and carapace length, weight and carapace length, weight and total length, maturity at size (carapace length) and fecundity at size (carapace length). It is suggested that a set of measures including catch control, effort control, gear control and protected areas are combined to allow the recovery of this resource.

The local movements and activity patterns of American lobsters, Homarus americanus, were monitored inside a 50 m by 50 m underwater enclosure (mesocosm) using ultrasonic telemetry. Forty-four lobsters of both sexes, ranging in size from 62 to 93 mm in carapace length, were continuously tracked for 2-10 days in 2002 and 2003. As a population, the movement rate of lobsters depended on time of day, as defined by dawn, day, dusk or night. Lobster movement rates were significantly higher during night and dawn than day and dusk hours. Movement rates did not differ by lobster sex, size or between years of the study. The effect of time of day differed between lobsters, and there was considerable variability in the time of day when individual lobsters were most active. Thirty lobsters moved significantly more during the night, five moved significantly more during the day, and nine did not move significantly more during the day or night. Therefore, while there was a general tendency for lobsters in this study to be more active at night, certain factors in their natural habitat modulated this nocturnal bias, which led to a tremendous amount of variability in their daily patterns of behavior.

This laboratory study investigated design features for artificial reefs to be used as enhanced juvenile lobster habitat. These features included size of brick shelters, size of rocks in rock piles, and the character of the underlying substrate. Experiments using brick shelters tested the ability of two lobster sizes (50-59 and 82-89 mm CL) to enlarge shelters by digging in sand-gravel bottom. If the gravel size was 1-2 cm both lobster sizes occupied > 90% of shelters by 22 h and the difference between occupancy at 2 and 22 h was not significant. If gravel size was 3-5 cm or 6-8 cm fewer shelters were occupied and the excavation of the sand/gravel took longer. Piles of three sizes of rocks were each placed on hard bottom as well as sand/1-2 cm gravel bottom, and the number of lobsters occupying each rock pile noted after 2-days. Six times more 70-79 mm CL lobsters and 1.7 times more 50-59 mm CL lobsters occupied rock piles on sand/gravel than hard bottom. For all rock sizes and substrates combined, three times more small than large lobsters sheltered in rock piles. The greater sheltering by lobsters on sand/gravel bottom and by smaller lobsters was thought to be related to the size of shelters available or that could be created between the rocks and the bottom by excavating under the rocks. Nearly all lobsters in the piles were located between the rocks and the bottom rather than among the rocks. A final experiment compared occupancy of 0.7 m and 1.2 m diameter rock piles by 60-69 mm CL lobsters where both pile sizes were of large rocks on sand-gravel. The larger piles attracted more lobsters, but neither the number/m² nor number/m circumference were significantly different. In summary, the substratum beneath a rock reef should be considered part of the reef's structure. Reefs housed more lobsters if the reef was placed on substrate they could excavate. Excavating a sand-gravel mix was easier where the gravel was smaller than 3-5 cm. Because lobsters mostly occupy shelters under the reef, reefs several rocks thick would add little to shelter availability. Occupancy of rock piles was related to rock and lobster size.

Pioneering work by J. Stan Cobb described how habitat architecture and body size scaling affect shelter-related behavior of American lobsters. Subsequent research suggested that shelter availability and competition could set local carrying capacity and demographics for this species. To determine how shelter spacing affects population density, the intensity of intraspecific competition and the distribution of body size for this species, I deployed sets of 10 identically sized artificial shelters spaced at distances of 2.5, 0.5, 1.0, 1.5 and 2.0 meters on otherwise featureless substrate at 10 m depth in mid-coast Maine, U.S.A. Five sets had two parallel strings of five opposing shelters and an additional linear string set 2 m apart without opposing shelters was the most widely separated treatment. Shelters spaced 1 m apart and closer had higher lobster population densities, more intraspecific competition and higher proportions of empty shelters. Surprisingly, lobsters there were also significantly smaller, declining from 62.7 mm to 50.8 on the carapace (CL) for 2 m linear to 0.25 m spaced shelters, respectively. Nearly all 932 lobsters measured in this study were juvenile (< 90 mm CL) and preharvestable (<83 mm CL) sized, so mate selection and fishing effects were unlikely. At the scale of the experiment, larger lobsters leave or avoid areas of high lobster population density and intense competition for areas of low population density and relaxed competition (called “demographic diffusion”). Scuba surveys in coastal zones found lobster population densities scale with shelter densities and were highest in boulder habitat where, like the experiment, more than half the shelters were vacant. Fisheries independent scuba and trawl surveys in Maine's shallow coastal zone repeatedly recorded declines of preharvestable lobsters larger than 60 mm CL in size and increases of those sizes offshore and in deep water. It is possible that this demographic diffusion is driven by behaviors associated with intraspecific shelter competition.

An outbreak of shell disease in American lobster (Homarus americanus) over the past several years has generated a great deal of attention and concern regarding its causes and spread into New England coastal waters. An examination of the disease within Massachusetts state waters was conducted from 2000 through 2004. The overall average incidence observed in our data was 3% males and 8% females. Female lobsters were more likely to exhibit disease symptoms than males, and larger lobsters were more likely to possess disease symptoms than smaller lobsters. Disease incidence was highest in May and June, immediately prior to the molting period, and decreased dramatically through the molting season. We detected a north to south latitudinal gradient of increasing shell disease prevalence along the Massachusetts coast. Over the course of our study period, we found relatively constant low levels of shell disease in both the Gulf of Maine and Outer Cape Cod regions. However, a significantly higher level of shell disease was recorded in the Buzzards Bay region, indicating important differences in regional prevalence of disease. Our data suggest that this gradient in shell disease may be related to an interaction between water temperature, sexual maturity, and intermolt duration. There is a significant correlation between disease incidence in Buzzards Bay and a series of warmer than average water temperatures from 1999 to 2003, which suggests that temperature may be a primary factor related to the recent outbreak of epizootic shell disease.

A shell disease epizootic is described for the American clawed lobster (Homarus americanus) populations in southern New England. This paper presents a conceptual model for examination of shell disease and presents evidence to support three hypotheses. Hypothesis one proposes that epizootic shell disease prevalence has increased in wild lobster populations; hypothesis two proposes that there are population-level effects of shell disease and hypothesis three explores the relationship between shell disease, and environmental and anthropogenic disturbances. This conceptual model links environmental stressors to physiological upsets and disease to population level impacts and can serve as a general model of disease in the marine environment.