Tanaidaceans have a worldwide distribution, with 36 families, 316 genera, and 1575 extant species described. This study aimed to compile the resulting taxonomic information for Brazilian waters obtained to produce the available online catalogue Taxonomic Catalogue of the Brazilian Fauna. Results show 63 species described for Brazilian waters: 30 Apseudomorpha and 33 Tanaidomorpha, distributed in 46 genera and 18 families. For apseudomorphan, Kalliapseudidae is the most diverse family (12.7%), followed by Apseudidae and Parapseudidae (9.5% each). For tanaidomorphan, Typhlotanaidae is the most diverse (15.9%) followed by Leptocheliidae (9.5%) and Tanaididae (7.9%). In Brazilian waters, more than 60% of Tanaidacea species are distributed in shallow waters (42 species; 63.6%), including continental areas, and about 1/3 are recorded from deep-sea (24 species; 36.4%). Southeast Region of Brazil holds most records with 46 occurrences, followed by the Northeast Region with 19 occurrences. Our results highlight the increasing number of publications and new Brazilian tanaids species in the last 15 years, and this is directly correlated to where specialists in alpha-taxonomy, systematics/phylogeny, and ecology are based in. Our current dataset also indicates an important aspect regarding the lack of taxonomic experts of Tanaidacea worldwide, but especially in Brazil. This study gives an overview of all the information that may help elucidate future research on the taxonomic diversity of tanaidaceans in Brazil, thus it is expected that this may encourage further studies and specialists for the group.

Mantis shrimps are commercially important crustaceans in many areas of the world. In contrast to the relatively common studies of adults, limited studies have been attempted of larvae because of a lack of identification keys. The objectives of this study were two-fold: (1) to link wild-caught larval specimens from the Seto Inland Sea to a certain species and (2) to present a detailed morphological description of the last larval stage. The resulting molecular phylogenetic tree based on 16S rRNA gene sequences strongly implies that our larval specimens were linked to Levisquilla inermis, which was barcoded from a newly collected adult specimen with a morphological identification. K2P genetic divergence was found to be 0% among the larval and adult specimens. The congeneric species L. jurichi was the sister group of the L. inermis cluster, but the K2P distance between them was 3.4%, and it was considered a distinct species. Morphological observations provided five major distinguishing characteristics of the last-stage larva of L. inermis: (1) propodus of second maxilliped with three basal spines, (2) all five pleopods possessing an appendix interna with cincinnuli, (3) exopod of uropod longer than the endopod, (4) distal margin of the exopod of the uropod reaching the lateral tooth of telson, and (5) telson with nine intermediate denticles. Overall, our results reveal the importance of combining molecular and morphological analyses for solving stomatopod larval identification. This finding can be used to support and facilitate future research on the taxonomy and biodiversity of stomatopod larvae.

Glencartholm in Dumfries and Galloway, Southern Scotland, is one of the most important Palaeozoic fossil fish sites in the world, with a fauna containing more than 30 species. Originally discovered in the bank of the River Esk in 1879, further collecting in the 1930s removed all the accessible fossiliferous strata. These strata were not known to occur elsewhere and despite the site's international importance, details of the section including the fossil bearing beds have not been described. An excavation of a new exposure at Mumbie, 50 metres east of the original site, was undertaken by Stan Wood in the 1990s. Sediments were logged over an 18-metre section. Three separate fish beds were identified and more than 200 specimens of ray-finned fish collected, including one possible new species. Differences in scale colour enables fishes from the different horizons to be distinguished. This should allow material collected previously to be more accurately assigned and assist palaeoecological analysis of the site. In addition to ray-finned fish, cartilaginous fishes were collected together with plants, bivalves, crustaceans, scorpions and horseshoe crabs which have not previously been reported from Glencartholm.

Ucides cordatus is a semi-terrestrial crab and key species endemic to mangrove areas of eastern Americas. In North-eastern Brazil this crab holds a major socio-economic function for artisanal fisheries, as in the São Francisco River Estuary (10°30′27″S 36°23′45″W). Nevertheless, decreases in this species’ stock have been reported since 2000, requiring assessments of the crab population for conservation and management purposes. This study aims at assessing the population status and the fishery potential of this species in the mangroves of this estuary and suggests strategies for its fishery and conservation, according to the guidelines of the National Management Plan for U. cordatus Sustainable Use. Six different sites established in 30 km2 of mangroves were sampled, with the density of U. cordatus burrows estimated to evaluate the population structure using the measure of burrow diameters. Results show that the crab mean burrow size was 56.82 (±12.2) mm and that the medium-size crabs (40–70 mm) are the most abundant. The total mean crab density was 1.2 crabs m−2, from which the density of crabs in commercial size (0.85 ± 0.55 crabs m−2) was significantly higher than those in non-commercial size (0.35 ± 0.21 burrow m−2). These mangroves showed a high potential for the crab fishery, with an immediate extractive potential (IEP) of 71.2% and future extractive potential (FEP) of 28.8%. Nevertheless, a lower crab density, probably due to high crab mortality, mangrove deforestation for shrimp farming and high fishery pressure, is a limiting factor for local fishery. We conclude that mangrove areas more appropriate for U. cordatus fishery (extractive areas) show higher mean crab size, IEP and density of commercial crabs, wherein a fixed exploitation rate or/and a fixed escapement rule should be considered. Exclusion areas, intended for the conservation, show lower values of these population parameters and higher FEP, wherein the fishery should be prohibited. These management strategies should also be considered in other Brazilian mangrove areas showing similar crab population structure, thus contributing to the National Management Plan for U. cordatus Sustainable Use.

Hyperiid amphipods are holoplanktonic marine crustaceans that are known as temporary symbionts of different groups of gelatinous zooplankton. The nature and dynamics of these associations are still poorly understood, particularly in deep waters. The mesopelagic and deep-living planktonic fauna off Monterey Bay, California (down to 4000 m) was surveyed using a remotely operated submersible (ROV) and blue-water diving (BWD) between September 2005 and January 2008. In this work we report our observations on a total of 51 symbiotic associations observed in situ (not from zooplankton samples), between hyperiid amphipods and various taxa of gelatinous zooplankton. We present the first information on the symbiotic relations of the hyperiid Vibilia caeca, and we provide data of 34 previously unknown symbiotic associations. The host range was expanded for several widely distributed hyperiid species. These findings suggest that the symbiotic associations between hyperiid amphipods and gelatinous zooplankton in deep waters deserve further study worldwide.

Contrary to earlier beliefs, crustaceans are present in ice-covered lakes of Antarctica. Interpretation of the significance of this has been hampered by the absence of robust identification of taxa present. We examine cyclopoid copepods from three widely separated lakes. All belong to the michaelseni group of the genus Diacyclops, which is widespread across Continental Antarctica, but do not fit into any existing species. Two new species were identified from eastern Antarctica, D. walkeri from Pineapple Lake (Vestfold Hills) and D. kaupi from Transkriptsii Gulf (Bunger Hills). Most significant was a dense population of a new epibenthic species (D. joycei) associated with microbial mats in Lake Joyce, one of the smaller McMurdo Dry Valleys lakes. This represents the first record of adult cyclopoid copepods from the ice-covered lakes of the Transantarctic Mountains. Continental Antarctica is the centre of diversity for this group of crustaceans and we argue that this is better explained by persistence through past glacial advances rather than by recent post-glacial colonization. The existence of a species endemic to Lake Joyce but apparently absent from other Dry Valleys lakes is discussed in relation to our understanding of the history of the McMurdo Dry Valleys lakes and their faunas.

Freshwater migratory shrimps, an important component of tropical aquatic ecosystems, are vulnerable to land-use change during their upstream and downstream migrations. At La Selva Biological Station in the Sarapiquí region of Costa Rica, shrimp population data were collected between 1988 and 1989, before massive land-use change occurred downstream that could potentially affect shrimp recruitment upstream. Using generalized linear models and a Bayesian inference framework, the relative abundance of Macrobrachium olfersi between recent (2008–2011) and historical time periods (1988–1989) was compared in three stream reaches. Shrimp relative abundance in two stream reaches within the protected area of La Selva was relatively constant yearly and between recent post-disturbance (2008–2011) and historical pre-disturbance (1988–89) time periods. In contrast, a stream reach bordered by pasture accessible to fishermen, showed an 87% decrease in relative abundance between recent and historical time periods suggesting site-level disturbance, possibly from fishing. The lack of change between historical and contemporary sampling periods within interior-forest stream reaches suggests that shrimp populations in protected forested reaches are resistant or resilient to certain land-use changes occurring downstream.

This 35-d feeding experiment examined in juvenile shrimp Penaeus monodon (3·3 g initial body weight) the effects of methionine (Met), choline and cystine on protein accretion and the activity of two key enzymes of remethylation (betaine–homocysteine methyltransferase; BHMT) and trans-sulfuration (cystathionine β-synthase; CBS). The interaction between Met and choline was tested using semi-purified diets either adequate or limiting (30 or 50 %) in total sulphur amino acid (SAA) content with a constant cystine:Met ratio. The diets contained either basal or excess choline (3 v. 7 g/kg feed). Cystine was added to two other 30 and 50 % Met-limiting diets to adjust the SAA supply to that of the control diet in order to evaluate the interaction between Met and cystine. As expected, N accretion was significantly lower with the SAA-limiting diets but increased back to control levels by the extra choline or cystine, demonstrating their sparing effect on Met utilisation for protein accretion. We show, for the first time, the activities of BHMT and CBS in shrimp hepatopancreas. Only BHMT responded to the SAA deficiencies, whereas the extra choline and cystine did not stimulate remethylation or down-regulate trans-sulfuration. Our data also suggest the capacity of P. monodon to synthesise taurine, being significantly affected by the cystine level in the 30 % SAA-limiting diets. Further research is warranted to better understand the metabolic regulation of taurine synthesis in shrimp and of the observed Met-sparing effects.

The toxicity of produced formation water (PFW) originating from four natural gas production platforms located in the Adriatic Sea (Italy), and of seawater samples collected near these installations is assessed by means of bioassays with Brachionus plicatilis, with the brine shrimp Artemia franciscana and with Paracentrotus lividus. The toxicological response of these specimens was evaluated in order to identify the most sensitive one, in the consumer compartment, and to design a bioassay battery specific for samples collected in the surroundings of a gas platform. Larval mortality of rotifers, larval immobilization of crustaceans, fertilization success/failure (sperm cell test) and larval (pluteus) development success/failure (embryo toxicity test) of sea urchins were taken as ecotoxicological endpoints. The PFW sampled on two platforms resulted toxic, while no toxicity was recorded in seawater samples collected in the vicinity of the platforms, even in coincidence with the PFW discharge operations. The species and bioassays employed have shown different responses to PFW: P. lividus turned out to be more sensitive than A. franciscana and B. plicatilis. In particular, the embryo toxicity test showed a higher toxicity than the sperm cell test.

We used a factorial approach to distinguish maintenance from growth requirements for protein, lysine and methionine in the black tiger shrimp, Penaeus monodon. Juvenile P. monodon (initial weight 2·4 g) were fed during 6 weeks one of ten semi-purified diets based on casein and purified amino acids (AA) as N source. The diets contained four levels of crude protein (CP, from 5 to 54 % DM diet) with two levels (% CP) of lysine or methionine (normal or 30 % deficient). Requirements were determined using linear and non-linear regression models. We could thus obtain the first ever data on maintenance (N equilibrium) requirements for CP and AA in P. monodon. CP requirements for maintenance (4·5 g/kg body weight (BW) per d) represented approximately 19 % of the CP requirement for maximal N gain (23·9 g/kg BW per d). The marginal efficiency of utilisation reached a maximum of 38 % for N, 0·77 for lysine and 1·62 for methionine using N gain as response. Lysine requirements were 0·20 g/kg BW per d for N maintenance and 1·40 g/kg BW per d for maximal N gain. Methionine requirements were 0·11 g/kg BW per d for N maintenance and 0·70 g/kg BW per d for maximal N gain. The lysine (5·8 %) and methionine (2·9 %) requirements for maximal N gain, expressed as percentage of protein requirement, agree with literature data using a dose–response technique with smaller P. monodon. The observed interaction between dietary CP and methionine for N gain demonstrates that requirements for indispensable AA (expressed as % CP) cannot be evaluated separately from CP requirements.

Scientific and commercial collecting have documented high levels of abundance among several species of marine snakes. Estimates of first-year mortality in populations of marine snakes range from 40 to 90%. The primary cause of this mortality is unknown. Storms, currents, sun exposure, dehydration and fire are abiotic factors that may control populations of marine and amphibious snakes. Disease, malnutrition and predation are biotic factors known to affect populations. In the literature there are isolated reports of predation by marine mammals, birds of prey, fish and invertebrates. Sharks in Australian waters are known to be predators on sea snakes. Our studies show that in the estuaries, intertidal mangrove creeks and mud flats of southeast Asia decapod crustaceans are important snake predators. Microhabitat overlap, exoskeleton armour and a respiratory advantage in an underwater standoff argue for their potential as potent predators. Field observations, a survey of crab stomach contents and encounters between snakes and crabs under laboratory conditions support this hypothesis. –

The tanaidaceans are among the most conspicuous and ecologically relevant benthic microcrustaceans in the marine realm but there are only a few records of species of tanaids associated with other marine organisms. During a long-term survey on the biology and distribution of the Caribbean manatee Trichechus manatus manatus Linnaeus in Mexican waters, parasites and epibionts were collected from 47 individuals that were captured for tagging in two bay systems. Well-established epibiotic communities of the tanaidacean Hexapleomera robusta (Moore) were found on eight of these animals; this tanaid crustacean formed patches of tubes adhered to the skin surface. Patches were distributed in different parts of the body surface but mainly along the backbone depression, the caudal zone, and on the lateral margins; in some instances they were related to clusters of barnacles. Highly significant differences of infestation rates were revealed between Chetumal Bay and Ascensión Bay, the latter representing better conditions (high salinity and hydrodynamism) for tanaid invasion and settlement on the manatee. It is speculated that the tanaid is a commensal; no visible damage was found in the host and its presence was not related to skin lesions. The tanaid probably captures suspended particles as the manatee feeds. This is the first confirmed record of a symbiotic association involving a tanaid and the Caribbean manatee. The tanaid species recorded (H. robusta) and the harpacticoid copepod Balaenophilus manatorum (Ortíz, Lalana & Torres), have both been recorded also as epibionts of sea turtles. The tanaid has been known from sea turtles for some time, but the copepod was first recorded from a manatee and was subsequently found on sea turtles a few years later.

The evolution of a character is better appreciated if examples of convergent emergence of the same character are available for comparison. Three instances are known among invertebrates of the evolution of axonal sheaths possessing the functional properties and many of the structural properties of vertebrate myelin. Comparison of these invertebrate myelins raises the question of what structural features must a sheath possess in order to produce the two principal functional characteristics of impulse speed enhancement and energy savings. This essay reviews the features recognized by early workers as pertaining to myelin in vertebrate and invertebrate alike: osmiophilia, negative birefringence and saltatory conduction. It then examines common features revealed by the advent of electron microscopy: multiplicity of lipid membranes, condensation of those membranes, specialized marginal seals, and nodes. Next it examines the robustness of these features as essential components of a speed-enhancing sheath. Features that are not entirely essential for speed enhancement include membrane compaction, spiral wrapping of layers, glial cell involvement, non-active axonal membrane, and even nodes and perinodal sealing. This permissiveness is discussed in relation to the possible evolutionary origin of myelin.

The diet and feeding behaviour of Illex argentinus were determined from analysis of stomach contents of squid caught during four bottom trawl surveys carried out over the Bonaerensis (34–40°S, autumn–winter 1991) and Patagonian (45–55°S, summer–autumn 1992) shelves of Argentina. Crustaceans, mainly Themisto gaudichaudii and, to a lesser extent, euphausiids were the most important components of the diet in both areas and years, although there were considerable geographical differences in the relative proportion of the main prey. In the Patagonian area, during summer and autumn of 1992, almost all squid preyed on crustaceans (percentage occurrence = 85.29%), followed by squid (11.76%) and fish (2.94%). On the Bonaerensis shelf, during autumn and winter of 1991, crustaceans were most important by percentage occurrence (56.96%), but fish and squid accounted for a large proportion of the diet (29.41% and 13.62% respectively). Myctophids were prevalent among the fish and cannibalism was on I. argentinus juveniles. Changes in diet composition with squid size demonstrated the opportunistic nature of I. argentinus feeding. Although large squids were able to catch large prey (fish, squid), they also fed on small crustaceans when available, especially in the Patagonian area. The relative abundance of different prey organisms probably determined the diet. In both areas and both years I. argentinus fed mostly during daylight hours, starting in the morning and reaching a maximum in the afternoon. No difference in feeding behaviour was observed between the sexes.

A diverse arthropod-dominated ichnofauna, associated with a poorly preserved crustacean fauna and soft-bodied ?medusoid impressions, is described from the Blaiklock Glacier Group of the north-western Shackleton Range (Coats Land), Antarctica. The ichnofauna consists of Asaphoidichnus, Beaconites, Didymaulichnus, Diplichnites, Gordia, ?Laevicyclus, Merostomichnites, Monomorphichnus, Palaeophycus, Planolites, Rusophycus, Selenichnites, and Taphrhelminthoides (ichnogen nov.). Three new ichnotaxa are recognised: Taphrhelminthoides antarcticus n. ichnogen. et ichnosp. is a bilobate trail, composed of two parallel flat lobes, separated by a median ridge with a characteristic figure-of-eight pattern. Merostomichnites gracilis n. ichnosp. is characterised by its proportions (external:internal width ratio >3) and series of 10 to 12, thin, linear tracks. Selenichnites antarcticus n. ichnosp. is characterised by small elongate horseshoe-shaped marks, the medial portion showing three to five transverse scratch-marks.

The palaeoenvironment is interpreted as extremely shallow marine water, possibly a tide-dominated estuary, based on sedimentological evidence and the composition of the ichnofauna. Radiometric and palaeomagnetic data indicate that this assemblage is Lower Ordovician in age, representing the first autochthonous Ordovician fossiliferous succession to be described from Antarctica. The succession shows several sedimentological and palaeontological similarities with the basal units of the Ordovician Table Mountain Group in South Africa, supporting palaeogeographic models placing the Palaeozoic Blaiklock basin close to the Ordovician Table Mountain basin.

European eels (Anguilla anguilla) from 2 sampling sites on the Rhine river (near Karlsruhe and near Worms) were investigated with respect to their parasite communities. Nine different metazoan species were found to live in and on the eels. The highest number of species was recorded from the intestine, which contained up to 6 different helminths. Among these, acanthocephalans were the most prevalent worms with the eel-specific parasite Paratenuisentis ambiguus as the dominant species of the intestinal component communities at both sites. Comparing the intestinal parasites from eels caught near Karlsruhe with those from Worms, the acanthocephalans showed a significantly lower abundance at Worms. A significantly lower mean number of intestinal helminth species as well as a significantly lower Brillouin's Index was found at Worms compared with Karlsruhe. This difference could be related to the abundance of the respective intermediate crustacean hosts. At the sampling site Worms the amphipod Corophium curvispinum was the dominant crustacean. Additionally, only the isopod Jaera istri and the amphipod Dikerogammarus villosus were found. All these crustacean species have only recently colonized the Rhine river system via the Main-Danube canal, built in the early 1990s. They are not known to act as intermediate hosts for any of the acanthocephalans found in the eels. The site near Karlsruhe exhibited a higher crustacean diversity, including Asellus aquaticus and different species of the genus Gammarus, which are all known intermediate hosts for the acanthocephalans found. Therefore, changes of eel parasite diversity can be correlated with the appearance of invading crustacean species (neozoans).

This paper develops briefly four examples illustrating the use of crustaceans as experimental animals in the field of metabolic and transport physiology. In cells of euryhaline crabs, organic substances such as free amino acids contribute much more than inorganic ions to osmotic adaptation, a feature that is now realized to be of general importance in living organisms. Anhydrobiotic and anaerobically dormant embryos of the brine shrimp Artemia provide very convenient models to study cellular control of metabolic depression. Studies on amphibious crabs have highlighted the constraints imposed upon gas exchange and acid-base balance by the very contrasted properties of oxygen and carbon dioxide in water and in air. Finally, the blood oxygen transport system of decapod crustaceans has been a model of choice to demonstrate the significance of an increased oxygen affinity for adaptation to environmental hypoxia. These examples illustrate the role played in the past as well as the great future potential of crustaceans as experimental animal models for general studies in Comparative Physiology.

For centuries, several species of prawns and crabs have been raised from wild-caught juveniles in coastal brackish-water fish ponds in various countries of south east Asia. The Indonesian "tambaks" are well known examples of such traditional practices. In western countries, since the turn of the century, advances of marine biology and fast increase of marine fisheries enabled the development of large-scale production and release of larval stages of American and European lobsters in a fruitless attempt to restock natural populations. After the Second World War, the increasing demand for crustaceans in United States and Japan was satisfied by opening new prawn fisheries all over the world. A major breakthrough was achieved with the development of hatchery technologies for the penaeid prawn Penaeus japonicus (Hudinaga, 1942 in Japan) and the caridean prawn Macrobrachium rosenbergii (Ling, 1969 in Malaysia), which occurred during the first decades of the second half of this century. Together with the increasing market demand in developed countries for sea food, this led to a considerable interest of both public agencies and private investors in marine shrimp and prawn culture. In western countries, a large number of pioneering commercial ventures, often based on assumptions not scientifically founded, failed. Nevertheless, the aquaculture production of prawns mainly based on wild-caught juveniles increased in South-East Asia and Central America during the 1980s. This overall positive trend should not hide important failures which occurred at a local scale, such as the Taiwanese crisis of 1988 due principally to environmental degradation, resulting in severe disease problems and a near collapse of the farming activity. Following the early period of hatchery technology development, the major scientific achievements were related to food requirements and formulation of compound diets for larvae, juveniles and adults and to a better knowledge of diseases caused by bacteria and several viruses which have been identified from hatcheries and intensive farming ponds. Additional new technological advances have emerged from recent research in the fields of physiology (endocrinology) and genetics. By far, the major part of the world production of marine crustaceans relies on penaeid prawns and, to a lesser extent, on Macrobrachium species. However, some other species of marine crustaceans have potential for aquaculture.

The economic aspects of marine crustacean aquaculture should be considered together with those of the fishing industry: market prices are rather similar, depending on the quality of the product. The balance between market demand and production is an important constraint which, in turn, establishes the success of prawn farming. Since the early 1980s, crustacean aquaculture has increased tremendously in both Asiaand America: the world production for 1991 approximated 700,000 tons, with more than 600,000 tonsfrom penaeid prawn culture.

The Dinantian Lower Oil-Shale Group of the Edinburgh area records the evolution of a SW–NE trending basin within an area of fluvial-dominated deltaic sedimentation, with rare marine incursions from the E. The sequence at Granton records the abandonment of a delta lobe, with deltaic sandstones overlain by lagoonal mud-shales. These thinly-laminated non-bioturbated mud-shales record low-energy, stagnant conditions. Fish, ostracodes and conchostracans inhabited the lagoon at this time.

Within the mud-shale sequence is the dolomitic Granton “shrimp-bed” which contains fenestrae, possible gypsum pseudomorphs and in situ shrinkage breccias suggesting periods of emergence. The “shrimp-bed” contains a number of laminae packed with soft-bodied fossils including marine forms, which resulted from brief marine incursions into the stagnant lagoon. The fluctuating salinity conditions seem to have favoured the development of an unusual fauna of shrimp-like crustaceans, fish, conchostracans, ostracodes and bellerophontid gastropods. This fauna appears to have suffered periodic mass mortalities during marine incursions which brought orthocone cephalopods, polychaete worms and conodonts into the lagoon, according to our current knowledge of the distribution of these marine taxa in the sequence.

The Granton sequence displays a variety of ductile and brittle deformation features most of which can be attributed to local SW-directed extension related to regional dextral strike-slip across the Midland Valley of Scotland.