The pontogammarid amphipod Dikerogammarus villosus, originally a Ponto-Caspian faunal element, has, in the recent 15-20 years, successfully invaded various aquatic systems in Europe including Lake Constance. In these rivers and lakes it had and still has severe ecological impact on native macro-invertebrates, often eliminating the native and earlier established gammaridean species. In order to test the hypothesis that the mode of food acquisition of D. villosus is of significance for this phenomenon, we focused on the mouthparts of D. villosus, i.e., mandibles, the two pairs of maxillae and the maxillipeds using SEM. Contrary to expectations, provoked by field and laboratory observations, the results of this study show that the mouthparts of D. villosus are not highly specialized just for carnivory and predation. Indeed, the stout mandibles, with their well-developed incisors enable to kill even prey with robust integument, but other modes of feeding are possible. On the maxillulae, maxillae, and maxillipeds we found setae that can be used, together with the gnathopods and the antennae, for filtering suspended algae and other small particles from the respiration current. The same structures are involved in collecting detritus. In contrast, D. villosus does not possess any specific tools for scraping periphyton from the substrate. Feeding on macrophytes may be possibly but not very effective because the surfaces of the molars are not well suited for grinding such plant material. It is shown that D. villosus is neither a shredder, as traditionally predicated for most gammarideans, nor is it a specialized carnivore, as predation experiments proposed, but rather unspecialized. Its ability to be carnivorous and to use a wide spectrum of other food may be an important reason for the success of this invader, being an advantage compared to mainly herbivorous gammarideans, which have been eliminated in many places by D. villosus.

Phenotypic traits often differ among conspecific populations inhabiting different environments. These morphological types may represent unique genotypes that are best suited to local conditions, or they may result from individual responses to local environmental conditions and thus represent plastic phenotypes. The barnacle Chthamalus fissus, commonly found in the upper intertidal of southern California and Baja California, Mexico, exhibits three morphs: one with an oval operculum, one with a narrow, slit-like operculum, and a relatively uncommon bent form with the operculum opening on one side. The aim of this study was to determine if differences in shell morphology among two populations of C. fissus separated by approximately 100 km result from local adaptation or are the result of plasticity in development of the barnacle shell. A reciprocal transplant experiment was conducted in which rocks with attached juvenile barnacles were transferred among populations from La Jolla, California, USA, where adults exhibit an oval operculum, and Ensenada, Baja California, Mexico, where adults exhibit either a narrow operculum or the bent morphology. The results indicate that barnacle morphology is determined by local conditions and is not due to genetic differences between the two populations. Results of a field experiment examining predation by the snail Mexacanthina lugubris lugubris suggest that oval morphs are more vulnerable than narrow morphs to this predator. Environmental factors that may be responsible for inducing this morphological variation are discussed.

Seven diet models offering were designed to investigate their effects on growth of the shrimp Litopenaeus vannamei, with a mean body weight of 1.380 ± 0.005 g (mean ± SE) at a temperature of 25 ± 0.5°C. The shrimps under different treatments were periodically fed with polychaete worm (PW, Neanthes japonicus) and commercial formulated diet (FD) with the ratio of 0:1, 1:4, 1:2, 1:1, 2:1, 4:1, and 1:0 in feeding frequency of PW followed by FD, respectively. Only one kind of food was offered each time and all the shrimps were fed twice daily. The result of the 45-day experiment showed that the specific growth (SGR_d) of shrimps fed with PW exclusively was 65% higher than those fed with FD only (P < 0.05); and the shrimps fed with the ratio of 4PW: 1FD, grew 15% faster than those fed with PW only in terms of SGRd (P < 0.05). The shrimps fed with the ratio of 4PW: 1FD spent a greater percentage of energy deposited for growth (G) from the energy consumed in food (C) and less percentage of energy lost for respiration (R) from C than those of shrimps fed with PW only. In contrast to feeding mixed diets, intermittent feeding of different diets can improve food conversion efficiency and avoid the waste of food caused by shrimp's food selection behavior. Therefore, the pattern of intermittent feeding on different diets was more practical and valuable in aquaculture.

The major chelae of reproductive male crayfish contain both smooth and plumose setae and are used for the perception of female odors. A comparative and morphological analysis of setae found on the major chelae of reproductive (form I) and non-reproductive (form II) male crayfish, Orconectes rusticus was performed in order to elucidate the distribution and function of smooth and plumose setae. In particular, the distribution of setae between reproductive forms was quantified as well as putative sensory functions, based on morphological characteristics, for both smooth and plumose setae. To accomplish these goals, scanning electron microscopy, a porosity assay, anterograde labeling, and acetylated tubulin (AT) immunocytochemistry were used. We found that form I crayfish have significantly more pockets of sensory setae and individual smooth setae on their major chelae when compared to form II males. Scanning electron microscopy revealed a terminal apical pore-like structure in smooth setae that was absent in plumose setae. Congruent with this finding, smooth setae absorbed crystal violet stain and DiI which labeled putative neural fibers. Conversely, plumose setae did not show any crystal violet or DiI staining. Furthermore, smooth setae contain fiber-like processes that are AT-immunoreactive and are located below the chitinous exoskeleton of the chelae. These fibers extend from the base of the smooth setae to the pore-like structure located at the distal tip. AT-immunoreactive fibers were not present in plumose setae. These results imply that smooth setae on the major chelae are putative chemoreceptors and plumose setae may serve a mechanosensory function. Coupled with previous behavioral studies, these results suggest that a dimorphism in the major chelae, found between male reproductive forms, enhances sensory perception during reproductive behaviors.

The morphological variation of Aegla neuquensis and A. riolimayana was studied using a geometric morphometric. Specimens included both allopatric and sympatric populations from rivers and lakes of the Argentinean Patagonia. Cephalothorax shape was analyzed throughout 16 landmarks representing the half configurations of all specimens after symmetrization process. Ordination analysis of the weight matrix revealed a clear distinction between the two species. Multivariate test run on the weight matrix for A. neuquensis and A. riolimayana was highly significant (P < 0.0001). Females and males of the two species differ significantly (P < 0.0001). Females of A. neuquensis and A. riolimayana present a wider posterior region, probably to carry eggs and juveniles. The first relative warp clearly indicates a difference in the shape of crabs inhabiting rivers vs. those living in lakes (P < 0.0001). Lake specimens show a more compact rostrum than river individuals. This is probably associated with the difference in the dynamics of both systems. The shape of A. neuquensis in allopatric populations appears to be similar to the shape of A. riolimayana, while sympatric populations appear much closer to the “typical” A. neuquensis shape. Thus, allopatric populations appear in some way to expand their shape toward A. riolimayana.

Structure of the mouthparts and foregut of Panulirus ornatus phyllosomata (stages I-VI hatchery reared, IX-X wild caught) were examined using scanning electron microscopy and histology to gain an understanding of ingestive and digestive processing mechanisms, to identify potential shifts in diet during development, and to suggest appropriate physical characteristics for the development of a suitable formulated diet for commercial aquaculture of this species such as size, texture, and buoyancy. Mouthpart and foregut structure indicates that P. ornatus phyllosomata are capable of ingesting zooplankton of any hardness during this life history stage and are only limited by their ability to capture and manipulate prey as the mandibular molars are well developed to masticate prey further. Mouthpart morphology changes little during development, however, the disposition of the mouthparts and size of the mouth aperture increases with each successive stage of development, suggesting a greater capacity to manipulate and ingest larger prey. The foregut of all developmental stages consists of a single chamber, with well-developed grooves, channels and setae, but lacks a gastric mill. Presence of well-developed main brushes, lateral setae, and development of a functional filter press at stage IV suggests an increased ability to triturate and filter prey internally, reducing both the time spent externally manipulating prey with the mouthparts and the vulnerability to predation in the open ocean. The results presented here suggest that formulated diets larger than > 428 μm, with a firm/hard consistency that allow the dactyli of the second and third maxillipeds to penetrate the diet without causing fouling of the setae would be suitable.

Historically, three obligate cave-dwelling species of Orconectes comprise an assemblage along the Cumberland Plateau of the southeastern United States, including Orconectes australis (with two subspecies, australis and packardi), O. incomptus, and O. sheltae. Using genetic data from three mitochondrial genes (cytochrome oxidase subunit I (COI), 12S, and 16S), we present evidence for four cryptic lineages excluding O. sheltae. The subspecies of Orconectes australis represent distinct taxonomic units with non-sister phylogenetic relationships and will be each recognized as separate species. Orconectes (Orconectes) barri is a new species of subterranean crayfish with a small distribution around the Kentucky - Tennessee state border in Mississippian limestone. This species was uncovered during a previous thoroughly-sampled phylogeographic survey of the southern Appalachians. Additionally, we assign genetic barcodes (COI sequences) and conservation status to each species for management direction and identification of newly discovered populations.

In a previous phylogenetic analysis of numerous species of the genus Munida and related genera from the West Pacific based on molecular and morphological data, the monophyly of this group with the exception of M. callista was established. Morphologically, M. callista is closely related to M. brucei, M. javieri, M. hystrix and M. plexaura showing morphological differences in the shape of the rostrum, the supraocular spines, and the ridges on the epistome with respect to the genus Munida. Moreover, the analysis of the mitochondrial genes 16S rRNA and COI showed an independent and monophyletic lineage from the genus Munida. Therefore a new genus, Babamunida, is proposed to accommodate these five species, based on morphological characters and molecular data.

The northeastern Atlantic spiny spider crab occurs from the British Islands to Senegal, where it is an important fishery resource. From morphological characters this crab has recently been proposed as a distinct species, Maja brachydactyla, although for commercial purposes it is still considered the same species as its Mediterranean congener M. squinado. We have studied variation at two mitochondrial genes in several crab populations from the Atlantic (putatively M. brachydactyla) and Mediterranean (M. squinado and M. crispata) basins, in order to clarify the taxonomic status of this crab in the northeastern Atlantic and Mediterranean regions. Phylogenetic analysis revealed that each of these three taxa forms a distinct and well-defined clade. While the divergence within each taxon was 0% for 16S and 0-0.3% for COI, divergence between taxa was 0.6-2.5% for 16S and 5.3-8.7% for COI; values that are in the range of the differences observed between other crustacean species. These results confirm the genetic distinctiveness of each taxa and support their designation as different species. Therefore, the Atlantic spider crab should be referred as M. brachydactyla, a fact that should be taken into account for conservation and commercial purposes.

The superfamily Portunoidea including extinct lineages is herein evaluated via cladistic analysis of adult morphological characters and traditional systematics. Nearly every fossil species has been examined via type material, or if this was not possible, through illustrations and original descriptions. The analyses indicate that the superfamily is much more diverse at the family level than has previously been recognized, and three subfamilies, Catoptrinae, Carcininae, and Macropipinae, are herein elevated to family status. One new family, Longusorbiidae; two new genera, Euronectes and Viaophthalmus; and two nomen nova are named herein in addition to the recognition of seven new combinations. The fossil record of each of the resulting families is evaluated and summarized, indicating that the superfamily extends into the Cretaceous but that many of the families are indeed much younger lineages.

We describe a new species of remipede crustacean from an anchialine cave system in the Exuma Cays, Bahamas. Pleomothra fragilis n. sp. is the second species assigned to the genus Pleomothra Yager, 1989. It is a relatively small species that occurs in sympatry with other remipedes, copepods, ostracods and amphipods. Pleomothra fragilis can easily be distinguished from Pleomothra apletocheles by the shape of its head shield, relatively long caudal rami, differently shaped, smaller maxillules, and a completely reduced lacinia mobilis on the left mandible. The reduction of the left lacinia and the sixth maxillular segment represent unique features that are only found in Pleomothra. At present, interpretations of these reductions are purely speculative since developmental data of remipedes are largely lacking. However, our recent collection of five larvae included a postnauplius that could be identified as belonging to the genus Pleomothra. The postnauplius exhibits transitional morphologic features that facilitate to evaluate autapomorphies in Pleomothra.

Two new calanoid copepods, Ridgewayia delfine sp. nov. and Ridgewayia tunela sp. nov., are described from anchialine caves in the Galapagos Archipelago. Details of the female genital segment and the female and male fifth legs help distinguish these species from each other and from other members of the same genus. The two new species belong to the Ridgewayia marki species-group, which are found predominantly in the Caribbean with one member in the Mediterranean and one in the Indo-West Pacific. These are the first species of Ridgewayia described from the Eastern Pacific. The volcanic origin of the Galapagos necessitates the dispersal of these ridgewayiids to the islands from other regions. It is currently thought that Ridgewayia is a relict from the Tethyan Sea and that members of the marki-species group crossed from the Caribbean into the Pacific during the circumtropical existence of this sea. The possibility remains that this crossover and colonization of the Galapagos occurred more recently while the Panama seaway remained open. It is clear that the current knowledge of the ridgewayiids is insufficient for a definitive conclusion. Further exploration is necessary to generate an exhaustive list of species of Ridgewayidae and their distribution.

Lysmata hochi n. sp., a new peppermint shrimp, is described from Bocas del Toro, Caribbean coast of Panama. All individuals were collected on near-shore fossil coral terraces with deep channels and caves, sparsely covered with seagrass. Besides the type locality, L. hochi n. sp. also occurs in Cahuita, Costa Rica, in a similar type of habitat. The new species can be distinguished from other species of Lysmata by the presence of an unguis-shaped accessory branch on the lateral antennular flagellum; the rostrum with three dorsal teeth, followed by two mid-dorsal teeth on the carapace posterior to the orbital margin; the number of carpal segments of the second pereiopod ranging from 21 to 24; the presence of two to four ventrolateral spines on the merus of the third pereiopod; the dactylus of the third to fifth pereiopod bearing two spines in addition to a bifurcated inguis; and the conspicuous color pattern, especially the irregular bright red bands on the pleon. Based on morphology and (where known) color patterns, L. hochi n. sp. appears to be most closely related to the Indo-West Pacific L. kuekenthali (De Man) and the eastern Atlantic L. uncicornis Holthuis and Maurin. Anatomical observations, field population studies and laboratory experiments indicate that L. hochi n. sp. is a protandric simultaneous hermaphrodite, with a primary male phase followed by a simultaneous hermaphrodite phase.

A new species of Periclimenaeus is described from Madeira Island, in the northeastern Atlantic Ocean. It is closest to P. pearsei Holthuis, 1951 from the western Atlantic, but it can be distinguished by the shape of rostrum, the size of exopod in relation to endopod in third maxilliped, the relation between the carpus and the chela of pereiopod 1, the relative size of second pereiopod minor chela, and the number of setae on appendix masculina. This is the first record of the genus Periclimenaeus in the eastern Atlantic.

The chromosomes of Crustacea, especially decapods, are usually numerous, small in size, and punctiform. These characteristics make it difficult for researchers to further investigate the chromosomes by light microscopy. As an alternative, the scanning electron microscopy (SEM) is recommended because it has higher resolution and is able to provide valuable three-dimensional data and X-ray microanalysis. The aim of this study is to obtain some fundamental knowledge for the preparation of the chromosomes of crustaceans for SEM observations. Since crustacean chromosomes are so small, impurities such as mucus and cytoplasm easily obscure the chromosome surface making it impossible for researchers to observe their fine structure. We used Artemia parthenogenetica as a model and confirmed impurities originating from the nauplii paste and the cytoplasm of the cells, and demonstrate that the nauplii paste can be removed by rinsing and the cytoplasm can be digested by trypsin.

Caprella mutica (Amphipoda) has been successfully reared through several generations per year for public exhibition in a tank of 500 L, more than five year after introduction of the species into the Port of Nagoya Public Aquarium, Japan. The tank was equipped with a coral sand bed filter, a circulation system, and a heater/chiller unit. Artificial seawater (Reef Crystals) was used as a medium. The diatom Phaeodactylum and hatched juveniles of Artemia were provided as food for C. mutica. Two years after the introduction, the sex ratio (females/(females males)) was 0.50. Males reached body lengths up to 20.5 mm, while the largest female was 10.4 mm long. The average number of embryos/female was 33.0. Embryos were 0.38 to 0.41 mm in the long axis, and 0.30 to 0.33 mm in the short axis. These reproductive characters enable the production of multiple generations in a single year.

We compared the effectiveness of light traps and plankton tows for sampling brachyuran crab larvae in Bartlett Cove, Glacier Bay, Alaska, U.S.A. during three nights each in July and August 2001 and June, August, and September 2002. Proportions of species and stages were used to compare larvae caught by light traps and plankton tows. Absolute numbers of larvae are difficult to compare because of the difference in sampling volume and duration of each method. Both methods captured early and late-stage larvae of four brachyuran families, Cancridae, Grapsidae, Pinnotheridae, and Majidae. However, light traps collected many late-stage (megalopae) cancrid larvae, which were rarely collected by plankton tows, suggesting that late-stage larvae may be undersampled by plankton tows. In contrast, plankton tows collected many early stage (zoeae) pinnotherid larvae, which may be undersampled by light traps. These results follow the same pattern as that found for tropical fish larvae, that light traps are a useful sampling device for settlement-size larvae. Light traps provide a simple method to collect high resolution temporal data on late-stage larval abundance, and their use has improved our ability to discern recruitment dynamics for decapod crustaceans.

The segregation of progenitor somatic cells from those of the primordial germ cells during early cleavage divisions occurs in certain copepods exhibiting the phenomenon of chromatin diminution during early embryogenesis. These species provide an interesting alternative to the usual reproductive strategy of other species of freshwater cyclopoid copepods. Levels of DNA for the soma and germ cells of Mesocyclops longisetus have been determined for individual nuclei by using Feulgen-DNA cytophotometry to monitor changes of DNA amounts during gametogenesis and early cleavage stages of embryogenesis. Germ cell nuclei of both female and male adults contain marked elevations of DNA, far in excess of expected 4C DNA level for their replication prior to meiosis. The elevated amounts of DNA in these germ cells are equivalent to the elevated DNA content found during the gonomeric divisions observed in embryos. Following the gonomeric divisions there is roughly a 40% loss of germ cell heterochromatin during the chromatin diminution stages of embryogenesis. The role of this excised DNA remains unclear.

Dark littoral submarine caves can act as enclaves of the deep aphotic zone in shallow coastal areas, and their survey has revealed the existence of a very particular fauna of specialized and poorly known organisms among which crustaceans are particularly well represented. In these particular habitats, the use of conventional sampling techniques, such as hand nets, is often not recommended since they disturb bottom sediments causing hazardous situations to scientific divers. The use of baited traps, while technically possible, is not always practical is such remote habitats. The present work describes a simple and inexpensive manual device that can be operated by divers in submarine caves and other cryptic habitats to recurrently catch small motile organisms such as mysid crustaceans, caridean shrimps, or even gobiid fishes. This small suction bottle derived and improved from the original “Sket bottle” design considerably reduces the risks of disturbing the cave's bottom sediment and can be easily operated using a single hand. The described sampling device can also be easily used outside caves, in a variety of particular habitats, e.g., rubble filled bottoms, branching coral reefs, cracks, and small holes on rocky surfaces, in which small motile organisms usually escape from traditional sampling gears, e.g., fishnets and traps, or simply go unnoticed by researchers during sampling.