Cysts of brine shrimp attached with a liquid adhesive to 12-mm diameter glass coverslips in a syringe-type fluid processing apparatus were flown aboard the NASA space shuttle Discovery, flight STS-60, from 3-11 February 1994, and were allowed to undergo postencystment embryogenesis and to hatch in microgravity. The shuttle flight and the ground-based control coverslips with attached cysts were parallel to the earth's surface during incubation in salt water. Based on the position of the cyst shell crack in the attached cyst population, the ground-control nauplii emerged mostly upward. On the shuttle in microgravity, although our method of detection of orientation would not reveal emergence toward the coverslip, the ratio of the position of the cyst shell crack in the population after hatching best fit the predicted values of a random direction for nauplii emergence. Centrifugation on earth was then used to create hypergravity forces of up to 73 g during postencystment embryogenesis and hatching. The upward orientation of emerging nauplii showed a high degree of correlation (r(2) =98.8%) with a linear relationship to the log of g, with 78.2% of the total hatching upward at 1 g and 91.0% hatching upward at 73 g.
The complete larval development of Gecarcinus lateralis lateralis (Fréminville, 1835), a gecarcinid land crab from Bermuda, is described and illustrated based on larvae reared in the laboratory. The species passes through six (possibly five) zoeal stages and one megalopal stage. The development through six zoeal stages to the young crab stage takes at least 29 days. Morphological characters of G. l. lateralis larvae are compared with gecarcinid species of which the complete larval development is known, i.e., Cardisoma guanhumi and C. carnifex .
On an intertidal sand flat in W Kyushu, Japan, adults of Callianassa japonica inhabited the upper tidal zone in 1979. Their distribution later expanded greatly to occupy almost the entire sand flat by 1983, the situation remaining unchanged until the end of the study in 1990. Occupation of deep-sediment layers by juveniles and hence their escape from mortality-causing factors near the sediment surface might be facilitated through the bioturbation of sediments and by the presence of burrows of established adults. -from Authors
The brine shrimp Artemia produces embryos (cysts) in a state of obligate dormancy called diapause. Diapause is terminated by a variety of treatments, including dehydration. Previous work suggested that some cysts can be induced to reenter diapause when exposed to prolonged anoxia. Results presented in this paper indicate that heat shock (42-43°C) can also lead to diapause induction. The basis for this proposal is the finding that the final hatching level of heat-shocked cysts is increased by a post-heat dehydration, a treatment known to terminate diapause. The respiration rate of postheat-shocked cysts was found to be much lower than controls. Electrophoretic profiles of proteins in extracts from control and heatshocked cysts suggest that the intracellular translocation of the major protein accompanies heat shock.
Crayfish are widely recognized as an important ecological component of stream systems, but there has been limited work to develop and evaluate the reliability of sampling methods for lotic crayfishes, especially efforts that are temporally and spatially comprehensive. We desired a quantitative method to assess crayfish communities in streams with rocky substrate. Our objective was to develop a method to obtain and compare representative density estimates with acceptable variance and reasonable effort, and to illustrate use of the method by using it to 1) describe and compare diurnal habitat associations by lotic crayfish, and 2) detect density changes over time. Our study encompassed four sites on two rivers, two seasons, and 8 y (1991-1998) to evaluate a 1-m2 quadrat sampler, and a sampling method that stratified effort among five macrohabitats to reduce variability. This method performed well for both seasons, detecting spatial differences among macrohabitats and temporal differences among years. Spatial differences were expressed as macrohabitat selectivity by the crayfish community, and showed a consistent trend across streams and seasons. In particular, macrohabitats with slower current velocities consistently had the highest densities. Temporal differences included documentation of decreased densities in several macrohabitats across 5 y. Sampling precision, measured by coefficients of variation, was acceptable but not considered high. Statistical power was good for detecting spatial differences, but reduced and variable for detecting temporal changes. Our findings 1) demonstrate the use of stratifying quantitative sampling for lotic crayfish communities by habitats, 2) confirm the importance of evaluating sampling methods, and 3) illustrate the consistent way in which Ozarks crayfish communities used available macrohabitats.
Biochemical changes, specifically in hemocyanin and glucose concentrations in hemolymph, glycogen in the digestive gland. were studied throughout the molt cycle in juveniles of Litopenaeus vannamei in a high salinity condition (36), and related to variations in the osmotic capacity of organisms. Increasing hemolymph volume before molting modifies circulating glucose and hemocyanin concentrations acting on the osmotic capacity. Variations in glucose concentrations are indicators of differential energy requirements throughout the molt cycle. Hemocyanin was used as an indirect indicator of the energy consumed by shrimp in various molt processes that affect the osmotic capacity. The co-variability of these metabolites is the result of the biochemical adaptations displayed by shrimp to maintain homeostasis. Their relation to changes in the osmotic capacity is given as a model to understand and predict events associated with molting under hypo-osmotic conditions.
19 pages.-- RECEIVED: 10 April 2000, ACCEPTED: 8 November 2000. The species of the genus Raymunida from the Pacific and Indian oceans are revised using morphological characters and the mitochondrial cytochrome oxidase subunit I sequences. Four new species are described (R. confundens, R. dextralis, R. erythrina, and R. insulata), and the status of R. bellior and R. elegantissima are revised. The species of Raymunida can be identified by subtle morphological characters, which match differences in mitochondrial nucleotide sequences. Therefore, the sequence divergences confirm the specific and phylogenetic value of some morphological characters (e.g., length of the mesial spine on the basal antennal segment, length of the walking legs). Furthermore, they confirm the importance of the color pattern as a diagnostic character. The widespread species (R. elegantissima), known from the Philippines to Fiji, shows minimal divergence between specimens from different localities (maximum of 3 nucleotide differences or 0.2% mean divergence). The phylogenetic reconstruction agreed with the monophyletic condition of Raymunida and its differentiation with respect to the genus Munida (in which Raymunida species had previously been included) and Agononida. Peer reviewed
The Journal of Crustacean Biology is a peer-reviewed, scientific journal containing papers of broad interest on crustacean biology and other marine arthropods, biographies of renowned carcinologists, book reviews of works on Crustacea, and pertinent announcements. Papers are published in English only, but abstracts or summaries in French, German, Portuguese, or Spanish may be added when appropriate.
Two fresh-water crayfishes, Astacus astacus and Procambarus clarkii, and a marine crab, Carcinus maenas, were examined for the presence of β-1,3-glucan-binding proteins in their plasma. By the use of a monospecific rabbit polyclonal antiserum to the β-1,3-glucan-binding protein of Pacifastacus leniusculus, 2 proteins from the plasma of Astacus astacus with molecular masses of about 105 kDa and 95 kDa as well as a 100-kDa protein in the plasma of Procambarus clarkii could be detected. No protein in plasma of Carcinus maenas cross-reacted with the anti-Pacifastacus leniusculus β-1,3-glucan-binding protein antibodies. The cross-reactive proteins from plasma of Astacus astacus were purified by immuno-affinity chromatography. The isolated proteins were homogenous as judged by electrophoresis on SDS-PAGE. Isoelectric focusing of the purified proteins gave pIs of about 6.1 and 6.4. The purified proteins from the plasma of Astacus astacus enhanced the activity of a hemocyte lysate supernatant-derived phenoloxidase of Pacifastacus leniusculus as did the β-1,3-glucan-binding protein of Pacifastacus leniusculus.
Nucleotide sequences from mitochondrial 12S ribosomal DNA are determined for 7 species of branchiopod crustaceans: 2 from the order Anostraca (Streptocephalus texanus and Linderiella santarosae), 2 from the order Conchostraca (Cyzicus mexicanus and Eulimnodia texana), 2 from the order Notostraca (Triops longicaudatus and Lepidurus bilobatus), and one from the order Cladocera (Moina brachycephala). They are compared to other branchiopod (Anostraca: Artemia franciscana, Cladocera: Daphnia pulex), and maxillopod (Branchiura: Savignium crenatum) sequences from the literature. The total set of nucleotides analyzed consists of sequences ranging in length from 250-267 bases. Multiple sequence alignments are generated and compared to assess the effects of alignment ambiguity on phylogenetic inference. Comparison of sequences among taxa revealed that (1) there is sufficient variation for phylogenetic analysis, (2) the variation is phylogenetically informative within and between some branchiopod orders, and (3) deep-branch phylogenetic resolution is limited by saturation effects. Phylogenetic relationships are inferred by parsimony analysis treating gaps as characters, confidence limits are estimated by both bootstrapping and the decay index. With a maxillopod sequence (Savignium crenatum) designated as an outgroup, the following results are obtained: branchiopod orders are monophyletic as sampled in this survey, with the orders Conchostraca and Notostraca clustering as sister taxa. Evidence for lineage specific rate heterogeneity of molecular evolution is discussed.
Approximately 350 base pairs (bp) of the mitochondrial 16S rRNA gene were used to study the phylogenetic relationships among 5 genera of the clawed lobster family Nephropidae (infraorder Astacidea), including Homarus, Homarinus, Metanephrops, Nephrops, and Nephropsis. Maximum-parsimony analysis, using a hermit crab, Pagurus pollicaris (infraorder Anomura), as an outgroup, produced a tree topology in which Homarus and Nephrops formed a well-supported clade that excluded Homarinus. The same tree topology was obtained from both neighbor-joining and maximum-likelihood analyses. Some morphological characters that appear synapomorphic for Nephrops and Metanephrops may be due to convergence rather than symplesiomorphy. The current taxonomy, therefore, does not reflect the phylogeny of this group as suggested by the molecular data. More molecular data and studies using homologous morphological characters are needed to reach a better understanding of the phylogenetic history of clawed lobsters.
The first sessile barnacle from a deep-sea hydrothermal vent of the East Pacific Rise (EPR) has been recovered by the French submersible Nautile from 17°25′S, north of Easter Island. It is similar in general appearance to the most primitive living balanomorph barnacle Eochionelasmus ohtai known from the North Fiji, Lau, and Manus Basins, in the Southwest Pacific (Yamaguchi and Newman, 1990; Galkin, 1992), but the morphology of its opercular plates, mouthparts, and cirri is distinct. Therefore, it is recognized here as a new species of the previously monotypic genus Eochionelasmus. However, it is anticipated that even greater differences will be found between the two species when fully developed individuals of the Easter Island form are found. If so, distinction at the genus-group level will need to be evaluated. The new species is not only the first record of a sessile vent barnacle from the East Pacific Rise, but it is also the first from a midocean ridge. This discovery corroborates the hypothesis that biotic exchange between midocean ridges and back-arc basins occurs relatively infrequently or was curtailed a long time ago.
Declining ambient calcium (Ca2+) concentrations in boreal, soft-water lakes of North America and Europe is one of many threats facing their biotic assemblages such as crayfish populations. We examined the specific exoskeleton calcium (Ca) concentration in Astacus astacus (Linnaeus, 1758) populations from a wide range of ambient Ca2+ concentrations to determine a possible correlation between the amount of Ca accumulated in their carapaces and the ambient Ca2+ concentrations. Exoskeleton Ca was the major constituent of the crayfish A. astacus carapaces in this survey (21.2 to 25.8% Ca of dry weight (DW)), whereas magnesium (Mg) displayed a disproportionately low constituent. The strong correlation between mineral contents of dry weight (DW) and ash weight (AW) ( r = 0 . 98 ) allowed us to refer mineral contents consequently to DW. A linear model using gender, length and ambient Ca2+ concentration (log transformed) explained 82% of the variation in carapace Ca content (as % DW). Astacus astacus females were slightly more calcified than males (0.4% of DW, when adjusted for ambient Ca2+ and body length). Large-bodied populations were slightly, but significantly more heavily calcified than those with smaller bodies: carapace Ca content increased by 0.2% DW for each cm increase in body length. The strong logarithmic effect of ambient Ca2+ implies that carapace Ca content increases by 1.7 × log(2) = 1.2% DW for every doubling of the Ca2+ concentration in the water.
Large male fiddler crabs prey on smaller conspecifics and other ocypodoid crabs. Large male fiddler crabs Gelasimus vocans (Linnaeus, 1758) either stayed at their burrows or left them to feed at the shoreline when the tide exposed the intertidal habitat in a river on Okinawa, Japan. Soldier crabs Mictyris guinotaeDavie, Shih & Chan, 2010 occupied burrows close to burrow-resident male fiddler crabs but some soldier crabs were active on the surface only briefly and the two species did not encounter each other. Soldier crabs released experimentally near the burrows of male fiddler crabs were often killed and carried by the fiddle crabs into their burrows. In contrast, soldier crabs left their burrows to feed at the shoreline alongside fiddler crabs and therefore the two species frequently encountered each other on natural conditions but the male fiddler crabs did not prey on the soldier crabs. Predation on M. guinotae by large male G. vocans was found to be related to burrow occupation.
Several studies have identified the potential for determining age in decapod crustaceans using apparent growth increments present within the mesocardiac, zygocardiac, and pterocardiac ossicles of their gastric mill. For a number of species, however, doubts have been raised in relation to this method, with studies indicating that these ossicles are lost in the exuviae at ecdysis, partially resorbed during the premoult period, or lost internally and subsequently broken down and digested after ecdysis. We examined which ossicles of the gastric mill are lost and replaced at ecdysis in the European green crab Carcinus maenas (Linnaeus, 1758), as well as the possibility that some ossicles are retained throughout the moult cycle. Examination of the foregut of individuals sacrificed < 1 h after ecdysis revealed that all gastric mill and foregut ossicles are lost at ecdysis. New ossicles are calcified to form the gastric mill and support the foregut after ecdysis. The gastric mill ossicles not lost in the foregut exuvia were instead lost internally. A partially resorbed mesocardiac ossicle was present in the foregut exuvia, with the zygocardiac and partially resorbed pterocardiac ossicles lost internally and subsequently digested. This is the first time gastric mill ossicles of a brachyuran have been identified as being lost internally at ecdysis. A similar phenomenon was previously described as occurring in the lobster Nephrops norvegicus (Linnaeus, 1758) and the crayfish Austropotamobius pallipes (Lereboullet, 1858). The study raises further questions and doubts regarding the utility of gastric mill ossicles for determining age in decapod crustaceans.
The dominant colour through the intermoult cycle of Carcinus maenas (Linnaeus, 1758) changes from green to orange, then to red. The external developmental stages of the rhizocephalan parasite Sacculina carcini Thompson, 1836 are correlated with this cycle such that the youngest stages predominantly occur when the crabs are green, the intermediate stages when they are orange, and the oldest when they are red. Fouling by the barnacle Balanus crenatus Bruguière, 1789 increases through this cycle as well, with both sacculinised and unparasitised crabs of orange or red colour being significantly more fouled than green crabs. Sacculinised green crabs with younger external parasite stages are generally least fouled, whereas orange and red crabs with late parasite stages are most fouled, but only female crabs show a statistically significant positive association between Sacculina infection and fouling. For both sexes, time since moulting, indicated by crab colour, is the most important predictor for fouling by B. crenatus.
The blue swimmer crab, Portunus pelagicus (Linnaeus, 1758), is an important component of the crustacean fisheries in Egypt. This fishery occurs mainly in two salt-water lakes in the Eastern Mediterranean, the coastal Lakes Bardaweel and Timsah, which is located about 100 km further south. We investigated for the first time the applicability of using growth band counts in thin sections of two gastric mill ossicles (mesocardiac and zygocardiac) as age indicator in the blue swimmer crab collected from the two lakes. There was no significant difference in band counts in thin sections of the two ossicles, although the zygo-cardiac ossicles were easier to process. Three growth bands were observed in the ossicles suggesting three years as the species life span. Meanwhile, size modal analysis suggested that the longevity of the species in the two lakes is only two years. Mean carapace width (mm) of the first two presumed year-classes obtained from the band counts and size modal analysis (y1 72.8 and 76.2 mm and y2 91.5 and 97.8 mm, respectively) were not significantly different in Lake Timsah. In Lake Bardaweel, however, the mean size observed at the first two years was different (y1 78.5 and 102.2 mm and y2 94.5 and 128.0 mm for the band count and size modal analysis, respectively). Sex-specific size-at-band counts (estimated age) was demonstrated for the species in both lakes. The models were fitted by power equations and there was no significant difference in the growth models between sexes in the two lakes. Further validation needs to be done to confirm the annual deposition of the growth bands before using the results on a routine basis.
ABSTRACT Frontal knob morphology of a few specimens of Artemia salina from Lymington, England, kindly provided by Dr. Boxshall (British Museum of Natural History, London), was examined by means of scanning electron microscopy in order to make comparisons with recently described morphology of North African (Sfax and Megrine, Tunisia) and Italian (Tarquinia, Latium; Sant'Antioco, Carloforte, Cagliari, and Su Pallosu, Sardinia) populations, respectively, referred to as A. tunisiana and A. salina (Mura, Del Caldo, and Fanfani, 1989; Mura, Fanfani, and Del Caldo, 1989). As to the shape of the frontal knobs and to their ornamentation, these species can hardly be separated one from another. Possible conspecificity is suspected, thus confirming data obtained by other authors with a series of cross breeds (Clark and Bowen, 1976; Baratelli et al., in press). New data concerning the sample from Lymington suggest that this population is conspecific.
A total of 336 specimens of the goldfish Carassius auratus Linnaeus, 1758 were examined in the Baihe River, Henan Province, China, for the presence of the parasitic isopod Ichthyoxenus japonensisRichardson, 1913. Only 20 goldfish (5.95%) were infected with single and paired isopods, and seven fish were previously infected. There was no significant difference in mean body condition (as K = (EW/L³) × 100, where EW is the eviscerated body weight and L is fork length) between infected (mean 1.450) and uninfected fish (mean 1.448; P = 0.95). The weight of gonads of the infected fish (N = 20) was calculated as zero because the gonads were too small to weigh or to identify the sex. There was also no significant difference in the GSI (gonadosomatic indices) between the infected fish (mean 2.66) and the uninfected individuals (mean 4.80; P = 0.30). The results suggest that the reproductive ability of the host was severely reduced by infection of the isopod, but that the gonads of the castrated fish could recover after the loss of the isopods.
The eastern Atlantic, Mediterranean, and Black Sea species, Liocarcinus depurator (Linnaeus, 1758), is recorded for the first time from the Western Atlantic (Brazil). This is the second invasive species of Liocarcinus Stimpson, 1871 recorded from the Western Atlantic along with L. navigator (Herbst, 1794). Single and occasional records of invasive species are an indication of unsuccessful attempts of introduction, but also possibly represent an early warning for human-mediated connectivity between potential sources and points of entry. The first individuals of the now widespread invasive species Charybdis hellerii (A. Milne-Edwards, 1867) first came to the Western Atlantic as early as 1965, therefore many years before the species managed to establish self-sustaining populations in the late 1980’s. An updated checklist of the marine and estuarine decapod invasive species from the Brazilian coast is provided. Sixteen species are now known from the region (farmed species excluded), seven of which have established self-sustaining populations.
Three types of mechanoreceptors were found on the cuticle of the first post-hatching instar of the trilobite larva of Limulus polyphemus (Linnaeus, 1758) examined by scanning electron microscopy: 1) tactile sensilla on the margin of the carapace of the prosoma; 2) sensilla, adapted to detect near-field sound energy in the form of particle motions and water currents, on the dorsal surface of the carapace covering the prosoma; 3) sensilla, having a helical structure of unknown function and not seen before, on the walking legs and pusher. The morphology of the mechanoreceptors of L. polyphemus, specifically the sensilla capable of sensing particle motions, may shed some light on the mechanisms of near-field sound or particle motion detection of these Jurassic “living fossils.”
Barnacles are sessile suspension feeders whose feeding efficiency and behavior is largely determined by the movement of water through their environment. Barnacles expend energy to feed actively in environments with low flow velocity, whereas they may feed passively at higher flow velocities, which is more efficient than active feeding. Many intertidal barnacles have been shown to switch between active and passive feeding modes as water velocities change, but little is known about the behavior of epibiotic species attached to mobile hosts, which are exposed to more consistent feeding currents. To assess the response of epibiotic barnacles to flow, laboratory-reared sea-turtle barnacles, Chelonibia testudinaria (Linnaeus, 1758), were subjected to a wide range of water velocities in both the presence and absence of food particles. Their behaviors were video-recorded and categorized using an automated behavior recognition algorithm compiled in R. Individuals of C. testudinaria only displayed passive feeding behavior, but did not feed at lowest test velocities. This species fed most at flow velocities between 25 cm s–1 and 40 cm s–1 (linear mixed effects model, F = 19.30, P < 0.001), a range that correlates well with the average swimming speed of two common host species, the loggerhead and green sea turtles, on which C. testudinaria resides. Chelonibia testudinaria displayed longer average feeding durations when food particles were absent than when food was abundant (linear mixed effects model, F = 11.76, P = 0.001), a result that is in line with the expectations of optimal foraging theory for suspension-feeding invertebrates. Lack of active feeding in this species may have evolved following the establishment of its epibiotic nature and may make this obligate epibiotic species entirely reliant on its hosts’ movements to provide a feeding current. This is the only barnacle species known to not facultatively switch between active and passive feeding modes.
Data are presented on growth in early juvenile (N = 36; 2.05–3.95 mm carapace length) Lithodes maja Linnaeus, 1758 reared at 6 °C in the laboratory, and on growth in males (N = 24; 45.9–113.3 mm carapace length) and females (N = 9; 61.0–81.3 mm carapace length) maintained at 6 °C in the laboratory. Growth rate did not differ significantly among early juvenile, males, or females, and therefore appeared linear across the size range examined. Intermoult period increased with increasing size. Growth and intermoult period models were combined to estimate size at age. Age at maturity appears greater in L. maja than in other species of Lithodes, suggesting that L. maja may be more vulnerable to fisheries overexploitation.
The population of the nonindigenous green crab Carcinus maenas (Linnaeus, 1758) in Salem Sound, Massachusetts, USA, was studied over a three-year period from July 2013 through June 2016 using baited traps deployed monthly at five sites. Seasonal catch per unit effort, sex, size, and color were determined and the role of habitat variables, including temperature, salinity, water depth, and substrate, were evaluated. Seasonal catch per unit effort was highest in the fall (October-December), followed by summer (July-September), spring (April-June) and winter (January-March). Few crabs were captured when water temperature dropped below 5 °C. Crabs captured at sites with very fine sand were larger than those captured on other sediment types. Females comprised 73% of the total catch of 7,822 crabs. Only 57 individuals exceeded 70 mm carapace width. Females were larger (mean = 51.7 mm) than males (mean = 48.8 mm). Green-phase crabs comprised 56.8% and red-phase crabs 43.2% of the catch. Green-phase crabs were significantly smaller (mean = 48.1 mm) than red-phase crabs (mean = 53.6 mm, P < 0.0001). Red-phase females were most common in the spring and green-phase in the fall, whereas red-phase males were most common in the spring and fall and green-phase in the summer. A yellow-phase category is proposed as a distinct intermediate between red and green phases. Merits of various types of traps and of bait were evaluated based on different trapping requirements and goals. This is the first investigation of multiple aspects of a population of C. maenas in Massachusetts. The findings should prove useful for researchers studying other populations of C. maenas, as well as for commercial crab fishers or others trapping green crabs for bait, or in efforts to reduce population numbers of this destructive invasive species.
Stomatopods engage in a highly dynamic lifestyle that includes ritual combat, territoriality, and active predation of live prey. Adaptations to this lifestyle include powerful raptorial appendages and an extraordinarily complex visual system, which includes 12-channel colour vision and the ability to discriminate the polarization of light. The neural processing underlying their colour vision has yet to be determined, though there is some evidence that the stomatopod colour vision system is based on wavelength recognition rather than spectral discrimination. We show that Odontodactylus scyllarus has an innate preference for objects that reflect wavelengths between 575 nm and 600 nm (corresponding to the human ‘yellow’). Comparatively, they show a reduced preference for objects that reflect both at shorter wavelengths, between 525 nm and 575 nm (human ‘green’) and at longer wavelengths, between 600 nm and 650 nm (human ‘red’). Within the wavelength preference, decisions are affected by the contrast of the object, with choice directed towards the version of the object that exhibited a greater Weber contrast against the background, despite reflecting in the same wavelength interval. As for other animals, the innate preference for objects reflecting particular wavelengths may act to increase the fitness of naive animals.
We characterized the optimal conditions for measuring serum phenoloxidase activity and its functional activity and susceptibility to an inhibitor and various activators in an anomuran crab, Albunea symmysta (Linnaeus, 1758). The substrate affinity of the phenoloxidase (PO) enzyme was determined using different phenolic substrates in which only diphenols were found to be oxidized. The enzyme was characterized as a catecholoxidase-type of PO and 3,4-dihydroxy-DL-phenylalanine (DL-Dopa), the enzyme showing the highest substrate affinity to the serum. The optimal enzyme activity was observed at 5 mM DL-Dopa in 10 mM Tris-HCl buffer at a pH of 7.5 at 25 °C for 10 min, and absorbance at 470 nm. Serum-PO activity was inhibited by 7 mM phenylthiourea (PTU), and activated by activators such as trypsin, chymotrypsin, pronase-E, and detergent-like sodium dodecyl sulfate (SDS). We also identified the chemicals causing in vitro inhibition or activation of the enzyme as a serum of the crab having a potent PO activity.
The western Pacific pinnotherid crab, Fabia obtusidentata Dai, Feng, Song and Chen, 1980, which lives in the saucer scallop, Ainusium (Pectinidae), is found not to belong to Fabia Dana, 1851 s. str. or Pinnotheres Bosc, 1802. In contrast to these two genera, E obtusidentata possesses a carapace not having longitudinal grooves, a third maxilliped in which the dactylus is slender and inserted one-third from the proximal end of the conical propodus, and a prominently elongated right third ambulatory leg with a long dactylus. It is here referred to its own genus, Amusiotheres gen. nov. Pinnotheres hanumantharaoi Devi and Shyamasundari, 1989, from India, is also transferred to the new genus.
We present a full description and analysis of the complete mitochondrial genome of a Pacific Ocean specimen of the coconut crab Birgus latro (Linnaeus, 1767), the largest extant terrestrial arthropod in the world. Our de novo-assembled mitogenome has a massive 16,161 times organelle read coverage, a length of 16,411 bp, contains 22 tDNAs (20 unique), 13 protein-coding genes, two rDNAs, and a putative control region of length 1,381 bp. The control region contains three microsatellites and two pairs of inverted repeats. Contrary to the mitochondrial sentinel gene concept, two-dimensional nucleotide analysis reveals higher GC-content in cox gene families than in nadh gene families. Moreover, cox gene families are more conserved than nadh gene families among the species of Coenobitidae selected for comparison. Secondary structure prediction of the 22 tDNAs shows major deviations from the cloverleaf pattern, which points to a relatively high rate of mutation in these genes. We also present a repertoire of mitochondrial variation between our male Okinawan coconut crab and an Indian Ocean specimen that consists of one insertion, one deletion, 135 SNPs, three MNPs and nine complex polymorphisms. We provide confirmatory evidence that the superfamily Paguroidea, to which the coconut crab belongs, is polyphyletic, that all the protein-coding genes of B. latro are under purifying selection, and that a Pacific versus Indian Ocean coconut crab population divergence occurred during the Pleistocene.
Whale-associated barnacles are intriguing in terms of their planktonic food sources, mating habits, and mechanisms of host attachment. We present observations of the whale-associated barnacles Coronula diadema (Linnaeus, 1767) and Conchoderma auritum (Linnaeus, 1767) obtained from dead humpback whales (Megaptera novaeangliae (Borowski, 1781)) collected in Korea. Shell bases of Coronula diadema are inflected and sharp-edged with hollow coring tubes at the periphery. The coring tubes are filled with whale skin, supporting the model that shell accretion into the whale skin is achieved by basal constriction to achieve strong attachment. Conchoderma auritum attaches to the shell surfaces of Coronula and has a pair of tubular ear-shaped structures on the capitulum. Both species have short and thick-segmented cirri that allow feeding in strong currents. The distal ends of the cirri in both species are often equipped with sharp, large claw-like setae, which are likely used to capture large zooplankton for food. Coronula diadema and Conchoderma auritum are simultaneous hermaphrodites. Coronula diadema can mate up to nine surrounding individuals. Conchoderma auritum lives in clumps and mating group size can up to 26 individuals.
ABSTRACT Hybrid crosses of females of Penaeus setiferus x males of Penaeus schmitti were obtained through artificial insemination. Mature females of P. setiferus (mean weight, 53 g ± 8.2 SD), collected from a wild population in the northwestern Gulf of Mexico, were inseminated with sperm of males of P. schmitti (mean weight, 27 g ± 5.3 SD) obtained from the western Caribbean Sea. Nauplii resulted from 7 of 19 artificial inseminations and were cultured to the subadult stage. Fertilization in all inseminations was less than 1% (4-4,300 nauplii per spawn), and subsequent survival of nauplii to postlarvae averaged 47%. Hybridization was confirmed by isozyme comparisons of parents and offspring using starch gel electrophoresis. Hybrids also exhibited uropod coloration typical of P. schmitti, the paternal phenotype, when sampled as subadults. Diagnostic differences between the parent species were found only by using a soluble protein stain and were not found in 11 specific enzymes tested. Sperm and ova were observed in mature hybrid offspring. These results are indicative of the phylogenetic relatedness and genomic compatibility of these species.
The complete larval development of the sponge crab Dromia erythropus collected in a shallow coral-sandy bottom off Dos Mosquises Island of the Archipiélago de Los Roques, Venezuela, is described. Five zoeal stages and a megalopa were obtained from laboratory rearing at temperatures of 27.2-28.6°C and salinities of 35-37‰. Development to the first crab stage took 28-30 days. A comparison of zoeal stages and megalopae among other dromiid species revealed species-specific characters for Dromia erythropus and possible generic characters for Dromia. Species-specific diagnostic characters between D. erythropus and D. personata lie in the number of setae on the exopodites of the maxillipeds and the strikingly different morphological appearance of the megalopa. The key diagnostic generic character for larvae of Dromia appears to be the presence of posterolateral spines.
The giant mud crab, Scylla serrata (Forskål, 1775), is a targeted fishery along its geographic distribution, both for domestic and international markets. Population genetic data, evaluated with genetic markers such as microsatellites, can be used to identify management units (stocks) based on genetic dissimilarities between locations, informing localized management decisions for targeted fisheries. Additionally, microsatellite loci can be used to identify released individuals from stock enhancement programs, while simultaneously monitoring genetic impacts of hatchery-releases on wild populations. We isolated and characterized 16 novel microsatellite markers; fourteen of the markers were further evaluated for population structure among three localities in the US-Affiliated Pacific Islands: Palau, Pohnpei, and Kosrae. The significant genetic differentiation observed between Palau and Kosrae/Pohnpei suggests the newly described markers would be capable of elucidating structure across the broader scope of the geographic distribution of the species. Given the international trade for live mud crab, the evaluation of structure would highlight potential issues regarding the transport of live animals between locations with genetically differentiated stocks. Additionally, a multilocus exclusion probability of 0.999, with as few as three markers, suggests the novel microsatellite markers would be capable of identifying hatchery-sourced individuals as part of a stock enhancement program.
A new species, Gammarus seideli n. sp., of a distinctly ornamented amphipod belonging to the family Gammaridae (Leach, 1813), is described from specimens collected from a spring in the northern Chihuahuan Desert, western Texas, USA. The new species belongs to the “Gammarus-pecos complex” of the northern Chihuahuan Desert, bringing the number of described species in the complex to four. Its range is currently restricted to a single spring. This small range puts the new species at a risk of extinction, making its description essential for conservation and for understanding the large degree of endemism among freshwater invertebrates in aridland springs. Also provided is a revised key to the fifteen described freshwater species of GammarusFabricius, 1775 of North America.
The mud crab Scylla serrata (Forskål, 1775) is a highly abundant and economically important species throughout coastal India. Cryptocyanin plays an important role during the moult cycle of brachyuran crabs, and the presence of cryptocyanin and haemocyanin in oocytes, embryos, and zoeas of various species suggests that cryptocyanin is available from the very early stage of cuticle formation in development. Cryptocyanin is highly similar to haemocyanin in structure, but it is a copper-free enzyme that lacks an oxygen-binding capacity. Cryptocyanin has furthermore been reported as an important factor in immunity in crustaceans. The precise molecular weight of the cryptocyanin protein from gill tissues of S. serrata (79.11 kDa) is reported with the help of the matrix-assisted laser desorption/ionization mass spectrophotometry (MALDI-MS) technique.
Primary producers exposed to ultraviolet (UV) radiation accumulate a range of metabolites as part of their UV-acclimation response. These metabolites play an important role in plant and algal UV protection. We investigated whether UV protection is transferred to consumers that feed on UV-acclimated algal biomass and showed that the copepod Tigriopus brevicornis (O. F. Müller, 1776) displays increased UV tolerance when fed on UV-acclimated Enteromorpha sp. (Clorophyta). We conclude that dietary transfer of metabolites produced in UV-acclimated biomass underlies the increased UV protection of the copepods. The data emphasise the complexity of the effects of UV radiation on the rock pool ecosystem.