White Crab Research Articles

Functional eye rudiments in the anchialine crab Munidopsis polymorpha (Crustacea: Galatheidae)

Abstract The white crab Munidopsis polymorpha (Crustacea: Galatheidae) is the only one of a species-rich genus not occurring in the deep sea. It is endemic to marine caves, anchialine pools and groundwaters of the volcanic island of Lanzarote (Canary Islands). The eye derives from the superposition type possessing a clear zone formed by the proximal extensions of the rudimentary crystalline cones. The number of ommatidia ranges among the lowest found in decapods and the optic ganglia are strongly diminished in size. The crystalline cones are rudimentary or lost and facets with individual corneas are not discernible. The rhabdoms are tiny and irregularly arranged in the rhabdom layer. Some rhabdoms display an open arrangement of rhabdomers with microvilli that are not aligned to form orthogonal layers. The eye is one of the rare exceptions of traits that despite being rudimentary is still partially functional. The absence of stabilizing selection is probably the reason for variability or reduction of the traits necessary for image formation. In contrast, negative phototactic behaviour is present, because light is still perceived by the eyes of M. polymorpha.

Performance Characteristics of Refined LC-FLD and HILIC-MS/MS Methods for the Determination of Paralytic Shellfish Toxins in Shrimp, Whelk, and Crab.

Paralytic Shellfish Poison (PSP) toxins have been reported in non-bivalve shellfish species, including crustaceans and gastropods. Routine surveillance of these species is currently conducted in parts of England. To date, detection methods have not been validated for these matrices. Validation is required to ensure the test is fit for purpose, to give greater confidence in any results generated and ultimately facilitates accreditation. The aim was to test and validate two independent PSP toxin detection methods previously validated for bivalve shellfish matrices, for applicability to commercial non-bivalve species of interest. Matrices were shrimp (Crangon crangon), common whelk (Buccinum undatum), and edible crab (Cancer pagurus). The two methods assessed were the pre-column oxidation high-performance liquid chromatography-fluorescence detection AOAC 2005.06 Official Method of analysis and an internationally validated hydrophilic interaction chromatography-tandem mass spectrometry method. Brown and white crab meat were assessed separately. A refined extraction protocol was implemented with an increased solvent to sample ratio. The same extraction protocol was utilized for both methods, allowing both methods to be run simultaneously. Method sensitivity, recovery, repeatability, and method uncertainty were characterized in all matrix/toxin combinations. Overall, both methods performed similarly to that previously reported in bivalve mollusks. Acceptability of the majority of toxin/matrix combinations was evidenced through comparison of method performance characteristics against specific performance criteria, including Horwitz ratio values. Both PSP toxin detection methods were found to provide acceptable performance for the monitoring of shrimp, whelk, and crab species. Two PSP toxin detection methods have been single-laboratory validated successfully for three non-bivalve shellfish species.

Elemental content of brown crab (Cancer pagurus) - Is it safe for human consumption? A recent case study from Mausund, Norway.

The brown crab (Cancer pagurus; the edible crab) is consumed worldwide and greatly appreciated for the essential elements (e.g., Zn, Se) that it contains. However, alongside these, it contains toxic elements that can pose serious risks for human health. For the brown meat parts of the brown crab, which contain considerable Cd concentrations, official legal limits of exposure are still lacking by regulatory bodies, rendering its consumption a potential food safety threat. In this study, a survey was conducted during 2016-2018 in a major Mid-Norway commercial crab fishing area of Mausund in Frøya municipality, Norway, where brown crab media samples were collected to assess the occurrence and profile of select elements, including toxic elements (Cd, Pb, Hg, Sr, As). A yearly median concentration ranging from 6.75 (2016) to 14.0 (2017) mg Cd/kg dry weight (est.: 2.11 (2016) to 4.37 (2017) mg Cd/kg wet weight) indicated high Cd concentrations, which were alarming when compared to the maximum allowed concentration of 0.5mg/kg wet weight set by the E.U. for raw white crab meat. Human exposures were assessed by estimating intakes of elements per 100g serving portion of dry edible media (white/brown meat), and the tolerable upper intake levels (ULs) (as specified by the United States National Academy of Sciences) were exceeded for Fe, Cu, Ni, Se, Ca, Mg and P. The median Se and Cd estimated human dietary intakes (EDIs) (from brown crab) were 8.21-8.59 and 9.64-20.0μg/kg body weight, respectively. The human intake dose (ID) of Cd (from brown crab) reached the order of a few tens of milligrams (mg). In addition, 33% of brown crab samples were found to be suitable for human consumption when the Se:Cd concentration ratio was applied and a stoichiometric excess of Se over Cd was indicated.

Mushrooms in Saudi Arabia (local and imported)

Mushrooms the beautiful edible macrofungi are important medicinally and nutritionally. The present study attempts to explore the locally grown mushrooms and also the imported varieties. Nine different genera of mushrooms were collected from different areas of Jazan and Abha belonging to Ascomycotina and Basidiomycotina. The nine genera were Agaricus, Agrocybe, Amanita, Boletus, Coprinus, Lepiota, Pleurotus and Podaxis belonging to Basidiomycotina. Morchella was the only genus belonging to Ascomycotina. The imported mushrooms from different countries mainly Holland, Japan, Malaysia and Thailand are collected from local markets from Abha and Riyadh. Eight genera of edible mushrooms which areidentified as Agaricus bisporus with different varieities like Silver creek and Portobello, Auricularia polytricha (Black fungi), Cyclocybe aegerita (Yanagi Mushroom), Flamullina velutipes, Hypsizygus tessellates (White Crab Mushroom), Lentinula edodes (Shiitake Mushroom), Lyophyllum shimeji (Brown Shimeji), Pleurotus or Oyster Mushroom with two species Pleurotus eryngii and Pleurotus ostreatus. Agaricus was the most common and predominant genera both as local and imported variety. Photographs of the mushrooms were taken and also the cross sections were studied. The structure of the gills is depicted by the spore print taken on the filter paper. More mushroom farms are required to be established so that they can be grown locally. As they are primary decomposers of organic matter they are also responsible for protection of environment and hence agents for controlling pollution. They are also eco friendly agents for recycling the waste.

Evaluation of the potential of ultrasound technology combined with mild temperatures to reduce cadmium content of edible crab (Cancer pagurus)

The consumption of crustaceans is correlated with certain health risks, particularly due to several highly toxic elements they contain, including cadmium (Cd). Although Cd content in one sole crab generally exceeds the total weekly recommended intake of cadmium as established by EFSA (especially in brown meat), efficient modern strategies to reduce Cd content in crabs still have not yet been developed. The objective of this research was therefore to evaluate the potential use of ultrasound technology in combination with temperature (50°–80 °C) with the purpose of releasing Cd from brown crab (Cancer pagurus), thereby reducing the Cd content in its meat. Female crabs were immersed in a water bath at 50, 65, and 80 °C in presence or absence of ultrasound; Cd concentration in the water was monitored along time. At the end of the process, Cd content in brown and white crab meat was likewise quantified. Treatment temperature did not bear an influence on the release of Cd in absence of ultrasound, but proved to be an important variable when ultrasound assisted the process. Ultrasound increased Cd release rates 8.7-, 2.1- and 2.7-fold in conjunction with the treatments at 50, 65 and 80 °C, respectively. The maximum percentage of Cd extracted (22.8%) was observed at 50 °C for an ultrasound input power of 200 W. These results have demonstrated for the first time that the application of ultrasound during the crab–cooking process could serve as an effective physical procedure for reducing the Cd content of crabs, thereby improving the product’s safety for consumers.

Levels of Cadmium in White and Brown Meat of Warty Crab (Eriphia verrucosa)

European Union regulations that establish the maximum cadmium (Cd) levels for crab take into account only concentrations found in crab muscle (white meat), mainly from appendages; therefore, other organs and tissues (brown meat) are excluded. The objective of the present study was to evaluate Cd levels in both white and brown crab meat, in order to achieve a more complete assessment of health risk related to human consumption of warty crab. Microwave digestion and atomic absorption spectrometry were used to determine Cd concentrations in warty crab (Eriphia verrucosa) samples collected from the southern Tyrrhenian Sea in Italy. Cd concentrations in all samples of white crab meat were found to be very low (below the limit of quantification), although brown crab meat showed significantly higher Cd concentrations (up to 5.629 mg/kg wet weight; mean value, 1.465 mg/kg). Thus, the consumption of brown meat, common among certain populations of the Mediterranean region, where whole crustaceans are traditionally eaten, substantially increased Cd intake, resulting in alarmingly high estimated weekly intake values.

Designing environmentally benign modified silica resin coatings with biomimetic textures for antibiofouling

Siloxane modified acrylic resin coatings with positive and negative replication textures were successfully fabricated by biomimicking the surface structures of natural lotus leaf and white crab shell via a replication method.

Abundancia estacional de crustáceos asociados a la captura artesanal de jaiba azul (<i>Callinectes sapidus</i>) en Sisal, Yucatán, México

Seasonal abundance and selectivity of the main crustacean species associated with blue crab fishing was studied at the port of Sisal, Yucatan, Mexico. For this purpose, 52 crab traps were used, which were divided into four parallel transects placed 100, 150, 200 and 250 m of the shoreline. Each transect consisted of 13 traps 20 m from each other. Traps were set at dusk and checked at dawn, standardizing the fishing effort to 17 hours/trap/day. A total of 832 organisms from eight species were caught; however, the study was conducted with four commercially important species: Blue Crab (Callinectes sapidus), white crab (C. similis), spider crab (Libinia dubia) and stone crab (Menippe mercenaria), accounting for 60.7%, 13.3%, 11.4%, and 11.6% of the catch, respectively. When dividing the total catch between climatic seasons (dry, rainy, and north wind), significant differences were detected in catch per unit effort (kg trap). The highest catch of C. sapidus and L. dubia was recorded in the dry season, while C. similis and M. mercenaria highest catch was in the north wind season. Most species showed a sex ratio different from 1:1, except for C. similis. Regarding selectivity or size at first catch (L50) values were 148, 90, 60, and 94 mm carapace width for C. sapidus, C. similis, L. dubia and M. mercenaria, respectively.

Dietary exposure to DDTs in two coastal cities and an inland city in China

Dietary intakes of dichloro-diphenyl-trichloroethanes (DDTs) of residents from two coastal cities: Guiyu (GY) and Taizhou (TZ) and one inland city: Lin'an (HZ) were investigated by collecting 73 food items (divided into 9 food groups). The oriental weatherfish and white crab (both from TZ) contained higher DDTs (112±1.81 and 70.1±1.81ng/g wet wt, respectively) than the maximum admissible concentration (50ng/g wet wt) set by the European Union for human consumption. Furthermore, 40% of TZ seafood, 56% of GY and 30% of HZ freshwater fish exceeded the guideline for subsistence fish eaters for DDTs (14.4ng/g wet wt) defined by the United States Environmental Protection Agency (US EPA). The estimated daily intakes of DDTs for TZ (52.1ng/kg bw/day) and GZ (31.5ng/kg bw/day) were significantly higher than for HZ (13.0ng/g wet wt, p<0.05), these values were below the US EPA oral reference dose (500ng/kg bw/day) and the Food and Agriculture Organization of the United Nations and the World Health Organization provisional tolerable daily intake (10,000ng/kg bw/day).

Food imprinting and visual generalization in embryos and newly hatched cuttlefish, Sepia officinalis

Juvenile cuttlefish spontaneously prefer shrimp to crabs. This preference can be changed by early visual learning during embryonic and postembryonic life and has been related to a form of food imprinting. Nevertheless, it is unknown whether generalization occurs in conjunction with this early learning process. We found that inexperienced hatchling cuttlefish preferred ‘black’ to ‘white crab’ for their first meal, the black ink envelope of cuttlefish eggs did not prevent embryos discriminating between black and white crabs and embryonic or postembryonic visual familiarization to ‘white crabs’ induced a subsequent visual preference for ‘white crabs’ over ‘black crabs’ in the hatchling's first meal. Finally, juvenile cuttlefish previously pre- or postnatally exposed to ‘white crabs’ preferred ‘black crabs’ to shrimp, indicating for the first time that prey generalization occurs as early as the embryonic stages in cuttlefish. Such cognitive abilities could confer important adaptive advantages in processing information about prey likely to be available in the egg-laying environment at hatching and in the course of juvenile dispersal.

Growth, protein retention and biochemical composition in Octopus vulgaris fed on different diets based on crustaceans and aquaculture by-products

The octopus, Octopus vulgaris, is one of the main targets for aquaculture diversification in Mediterranean countries. However, the development of octopus farming is limited by the lack of information regarding nutritional requirements of this species during its life cycle. In this study, five diets were tested on the biological performance (growth, protein retention and biochemical composition) of individually reared octopuses (n = 8 per diet), including three single diets constituted by: an endemic crab (the white crab, Plagusia depressa), a commercial crab imported frozen (the blue crab, Portunus pelagicus), and bogue ( Boops boops) discarded from fish farms (aquaculture by-product), as well as two mixed diets, containing a 60–40% of blue crab-bogue and white crab-bogue, respectively. The rearing period lasted 8 weeks. Octopuses that fed on a mixed diet constituted by blue crab-bogue showed a higher growth than those feeding on bogue as a single food item. No significant differences in growth were observed among individuals feeding on single food items. Highest protein retention was observed in octopuses fed on diets containing discarded bogue, associated with a high lipid and monoenes content in this food item, underlying the use of lipid as energy source in O. vulgaris. However, discarded bogue was deficient in ARA in comparison with octopus tissues, which did not seem to affect growth during the experimental period. These findings underline the potential of aquaculture by-products, particularly bogue, as an adequate diet for culturing O. vulgaris.

Studies on the immunoreactivity of the major allergen tropomyosin in mantis shrimp (&lt;I&gt;Squilla oratoria&lt;/I&gt;)

Crustacean is one of the eight kinds of allergen sources in coastal areas,which causes the IgE-mediated hypersensitive reactions with clinical manifestations including urticaria,angioedema,asthma,and even fatal anaphylaxis. Tropomyosin (TM) is the major allergen of decapod crustaceans with highly conserved amino acid sequences. The purpose of this study is to confirm whether TM is a major cross-reactive allergen in mantis shrimp (Squilla oratoria) which is taxonomically distinct from decapods and largely consumed as a delicacy in China. Quantification of TM in different species of crustaceans was also conducted. Muscle sample from mantis shrimp was homogenized with phosphate buffer to prepare heated extracts and separated by 12 % sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). A protein band with molecular mass of about 36 ku was detected by IgE-immunoblotting by all of the sera with crustacean allergy,suggesting it is the major allergen of mantis shrimp. This protein was further purified to homogeneity by acetone powder preparation,isoelectric point precipitation,ammonium sulfate fractionation (40%-60% saturation),and heat treatment. Purified protein was demonstrated to be TM by Western blot using polyclonal antibody against TM from Chinese mitten crab (Eriocheir sinensis). Heated extracts from other crustaceans including mud crab (Scylla serrata),Pacific white shrimp (Penaeus vannamei) and short necked clam (Venerupis variegata) were also prepared,and the cross-reactivity of TM from mantis shrimp with TMs from these crustaceans was confirmed by inhibition immunoblotting using polyclonal antibody against TM and inhibition ELISA using sera with crustacean allergy. Quantification by ELISA using polyclonal antibody against TM revealed that TM content in mantis shrimp muscle is much lower than that in Pacific white shrimp and mud crab muscle,which was about 45 times lower in mantis shrimp muscle than that in Pacific white shrimp muscle. However,its allergenicity seems equivalent to other decapod crustaceans as showed by inhibition ELISA using sera with crustacean allergy. This may be due to the degradation of TM in mantis shrimp by its endogenous serine proteinases and cathepsins which destroyed the IgG-binding epitope but not the IgE-binding epitopes. In conclusion,this study demonstrated that allergenicity of mantis shrimp is almost equivalent to decapods and TM is the major allergen in mantis shrimp with high cross-reactivity to decapod crustaceans.

Cryptic Color Change in a Crab Spider (Misumena vatia): Identification and Quantification of Precursors and Ommochrome Pigments by HPLC

Mimicry is used widely by arthropods to survive in a hostile environment. Often mimicry is associated with the production of chemical compounds such as pigments. In crab spiders, the change of color is based on a complex physiological process that still is not understood. The aim of this study was to identify and quantify the ommochrome pigments and precursors responsible for the color change in the mimetic crab spider Misumena vatia (Thomisidae). A modified high performance reverse phase ion-pair chromatography technique enabled us to separate and quantify the ommochrome pigments, their precursors, and related metabolites in individual spiders. Compounds such as tryptophan, kynurenine, and kynurenic acid occurred only or mainly in white crab spiders. In contrast, compounds such as 3-hydroxy-kynurenine, xanthommatin, and ommatin D occurred only or mainly in yellow crab spiders. Factor analysis ranked the different color forms in accordance with their metabolites. The biochemical results enabled us to associate the different phases of formation of pigment granules with specific metabolites. Yellow crab spiders contain many unknown ommochrome-like compounds not present in white crab spiders. We also found large quantities of decarboxylated xanthommatin, whose role as precursor of new pathways in ommochrome synthesis needs to be assessed. The catabolism of ommochromes, a process occurring when spiders revert from yellow to white, warrants further study.

“We're Our Own Boss”: Gendered Class‐Consciousness and White Privilege among Hooper's Island Crab Pickers

AbstractThis article analyzes the gendered class‐consciousness of white crab pickers of the Chesapeake Bay through their claim that they are their own boss. Although crab pickers work in a factory for a wage, have a boss, and punch a time clock, this article argues that gender, whiteness, kinship, and localized myths of hard work and independence tied to the coastal landscape formed a unique local and regional history linked to class and racial ideologies that actually allowed white crab pickers to contest packinghouse owners' authority over their schedules, speed, and other political aspects of work. The article analyzes ethnographic fieldwork, discourses in federal documents, and a strike by crab pickers to argue that white women's claim of self employment was an historically contingent process where class and class‐consciousness operated as relationships defined by women as they lived their own lives. The article concludes that scholars must separate class‐consciousness from class action and understand the political power of dominant classes to control the latter, especially in relation to gendered labor markets. Women crab pickers' claim of self‐employment points to a consciousness of oneself within a specific power relationship and subordinated position.

Quality Characteristics of Fresh Blue Crab Meat Held at 0 and 4°C in Tamper-Evident Containers

There has been a regulatory movement toward the required use of tamper-evident containers for fresh blue crab meat. North Carolina passed tamper-evident regulations in 1993. Blue crab processors had little information on possible changes in head-space gases, microbial growth, chemical decomposition, sensory quality, or shelf life caused by the new containers. Chemical, microbiological, physical, and sensory changes in fresh crab meat were monitored during 18 days of storage in ice and 13 days of storage refrigerated at 4°C. “Special” blue crab meat, chosen for the study, is the least expensive commercial form of white crab meat. The crab meat was packaged in four retail containers: copolymer polyethylene cups with polyethylene snap-on lids, copolymer polyethylene cups with snap-on polyethylene lids fastened to the cup with heat-shrink low-density polypropylene seals, copolymer polyethylene cans with aluminum easy-open ends, and copolymer polypropylene cups with a tamper-evident pull-tab on the lid. Control samples packaged in industry standard copolymer polyethylene cups maintained higher oxygen levels than meat stored in tamper-evident containers. No consistent differences in quality or shelf life were detected among the containers. Market shelf life was limited to 6 days for meat held at 4°C and 15 days for meat held at 0°C. Sensory quality deteriorated 6 days earlier for crab meat held at 4°C than meat held at 0°C. Collateral work showed that toxin production by Clostridium botulinum neither occurred following 18 days of storage at 4°C nor after 15 days of storage at 10°C. Definite spoilage occurred before any toxin production. The study suggests that blue crab processors can safely use the new tamper-evident packaging, which has little or no effect on product quality or shelf life. Processors may choose appropriate packaging options using price, packaging quality, market appearance, and ease of production as the deciding criteria.

VIBRIO PARAHÆMOLYTICUS GASTROENTERITIS AND INTERNATIONAL AIR TRAVEL

An outbreak of food-poisoning caused by the marine organism Vibrio para-hæmolyticus on an international charter airflight from Bangkok to London is described. This is the first such outbreak recognised in Britain. The food vehicle was cooked white crab meat in hors d'œuvres prepared at Bangkok. Kanagawa-positive strains of serotype O2/K3 were isolated from patients and from dressed crab meat in duplicate meals, as well as from raw crab meat, whole crabs, and crab claws.

Types, Distribution and Rhythmical Behaviour of the Chromatophores of Juvenile Carcinus maenas (L.)

Colour change in Brachyura is effected by chromatophores located within the hypodermis. Abramowitz (1935) found that Portunus anceps, the white crab, possesses three types of monochromatic chromatophore containing white, black and yellow pigment respectively, whilst P. ordwayi, the red crab, possesses three similar pigments and an additional red pigment. In this respect Uca pugilator (Carlson 1936) and Eriocheir japonicus (Matsumoto 1954) resemble Portunus ordwayi. Enami (1951) working on crabs of the genus Sesarma, described monochromatic black, white, red and vermilion chromatophores. All these workers concluded that the chromatophores are scattered throughout the hypodermis and do not form striking colour patterns. In 1937, Abramowitz described a 24-hour rhythm of colour change in the fiddler crab Uca, the animal having a dark day phase caused by the dispersion of the darker pigments, and a light night phase, the pigments being concentrated. Brown & Webb (1948) described how this rhythm persisted for as long as 30 days in continuous darkness, and was independent of temperature within the range 6-26? C. Brown, Fingerman, Sandeen & Webb (1953) in a further investigation of this 24-hour rhythm in U. pugnax, described a persistent tidal rhythm of melanophore expansion which was superimposed upon the diurnal rhythm leading to a third - a semi-lunar rhythm. Here the phase of melanophore dispersion bore a definite relationship to the time of low water in the area in which the crabs were collected. Fingerman (1955, 1956), described persistent daily and tidal rhythms of colour change in the blue crab, Callinectes sapidus, and in two other species of Uca, U. pugilator and U. speciosa. In all these cases, the crabs darkened by day and paled at night, with a supplementary dispersion of dark pigment at or near the time of low water. This investigation was performed to describe the types and distribution of chromatophores in Carcinus maenas, and to find out whether Carcinus, an animal which is known to have persistent daily and tidal rhythms of locomotory activity (Naylor 1958), has similar rhythms of colour change.