The species belonging to the genus Crangon Fabricius, 1798 only occur in the Northern Hemisphere both in Atlantic and Pacific waters. The higher number of species of Crangon in the Pacific suggests that they originated from this area. To date, a few studies have identified some common features between members of the genus, but the species have largely been ignored in taxonomic, phylogeographic, and ecological research efforts. Crangon are all carnivores or omnivores probably with a relevant ecological role; in some cases top-down control by the type species, C. crangon (Linnaeus, 1758), has been suggested. Several species live in shallow coastal waters and might represent abundant prey for fish including flatfish during their nursery period; the shrimp themselves prey upon the early life stages of flatfish. Because of their high abundance, some shrimp have commercial value not only for human consumption but also as bait. However, the taxonomic status within Crangon and genetic relationships among populations within species are still unsettled. Also, their geographic ranges and general life cycle features are poorly documented. Despite occurring only in the Northern Hemisphere, Crangon are originally temperate water species. Most have still a high upper tolerance limit but are also quite adapted to low temperatures. They might then have a high temperature tolerance range which will be beneficial in a climate change scenario. In this work we review previous investigations on the various species of Crangon across the spread of their geographic occurrence and highlight issues requiring further research.

The escape responses of twelve individuals of the stomatopod Odontodactylus havanensis (35–64 mm body length) were recorded with conventional and high-speed (60 and 500 images per second) video cameras. Unlike the typical pattern of escape swimming seen in most elongate Malacostracan crustaceans in which quick backward swimming is achieved by rapid pleonal flexion (tail-flipping), O. havanensis always swam forward during its escape response. Rowing of the pleopods provided thrust during swimming. The power phase was metachronal and the recovery phase was approximately synchronous. The mean stroke frequency, from high-speed video, was 17 Hz. With this swimming mode, speeds of 1.25 to 1.62 meters per second and 21 to 40 body-lengths per second were attained. The intermittent nature of the rowing propulsive mode led to temporally unsteady kinematics marked by periodicity. Although forward swimming via pleopod rowing is a very common form of locomotion employed by elongate crustaceans, it is typically observed only during relatively slow, “routine” swimming, with escape being driven by tail-flipping. Odontodactylus havanensis breaks this pattern. Further study into how this species is able to achieve such high speeds via rowing locomotion may yield new insights into our knowledge of animal locomotion through fluids.

We describe the structural and ultrastructural sequence of events that occurs during the acrosome reaction process in Cancer setosus Molina, 1782. No change is observed in spermatophores extracted from the male vas deferens and incubated in different concentrations of seawater; the spermatozoa are not released nor do they experience the acrosome reaction. Only spermatozoa from the masses in seminal receptacles of females undergo acrosome reaction. The acrosome reaction begins with an elongation of the acrosomal vesicle after the spermatozoa are incubated for 15 to 20 min in seawater. During this elongation, the material in the perforatorial chamber is extruded and spread on the outer side walls of the acrosome forming a ring-shaped opening at the anterior region of the acrosome. The ring-shaped material moves to the posterior region, thus increasing the diameter of the anterior opening of the acrosome. In the following stages, an acrosomal filament is extruded and extends beyond the anterior end of the acrosome. The distal end is enlarged and then divided into three thin terminal extensions.

Amphipod silk is a fibrous, self-secreted, adhesive substance employed in tube-building by amphipod species within the Corophiidea, Ampeliscoidea and Aetiopedidea. In the present study we provide a detailed characterisation of a novel, marine-based silk production system situated in pereiopods 3 and 4 in the corophioid Crassicorophium bonellii and the aorid Lembos websteri. The silk material is a mixture of protein and mucopolysaccharides. Ultrastructural and histological analyses revealed that silk in both species is produced in several rosette-type glands, presumed to be of two different types. These glands are distributed among all limb articles apart from the coxa but mainly in the basis and merus of pereiopods 3 and 4. Secretion commences in the basis and a thread-like secretion product leaves the glandular pereiopod through a cuticular pore near the dactylar tip. The silk's physical and chemical properties most likely change while moving through the dactylar duct, which subdivides into several small ductules and terminates in a spindle-shaped chamber. This chamber, which communicates with the exterior, may be considered a silk reservoir in which the silk appears fibrous. For the first time an independently evolved, marine arthropod silk processing and secretion system is described.

Clibanarius virescens (Krauss, 1843) is one of the most common and abundant hermit crabs in South Africa and in the Indo-West Pacific region, but little is known about its population structure or breeding in Africa. Cape Recife, South Africa, is the south-western limit of its distribution and was sampled over a 13-month period to determine shell use, population structure, reproductive output and breeding period of C. virescens. Shells of 17 gastropod species were found in use with Burnupena lagenaria predominating (73.4% of shells used). Males and females appear to partition the shell resource. Males use larger shells of the same types as females, but also use different suites of shells. The sex ratio is 1: 1.77 in favour of females, but males dominate the largest size classes. The breeding season occurs from mid-December to mid-July and ovigery correlates closely to sea surface temperature. Clutch size correlates strongly to crab size and shell volume. The population of C. virescens at Cape Recife has similar patterns of shell use as at other localities in Africa, but shows much larger clutch sizes than previously recorded in South Africa. This indicates that its life-history strategy at Cape Recife may differ from that at other localities within its range.

Studies of crustacean growth, including king crabs, have typically used modal analysis rather than growth of individual crabs. I studied the individual growth of several hundred juvenile red king crabs (initial size 14–35 mm carapace length, CL) that were captured from a pod in Kodiak, Alaska, in July and August 2000, and retained in the laboratory for up to 14 months. During that period, 295 crabs molted at least once, including a subset of 52 that molted twice, and a subset of 9 that molted three times. Mean molt increment (MI) was 5.5 mm, and did not differ significantly between the three molts. MI increased significantly with premolt size for molt 1, and proportional growth rate at molt 1 was greater than that of molts 2 or 3. The first molt occurred earlier (August–October) and at warmer temperatures among smaller crabs than among larger crabs, which molted in January–February at colder temperatures. Post-molt CL for first molts was a simple ratio: Post-molt CL = 1.25 · (Pre-molt CL) (R² = 0.9587, df = 291). Growth during the second molt was less than during the first molt, possibly reflecting a limitation imposed by the holding conditions. This is the first study to record growth information for individual juvenile red king crabs in the size range of 15–50 mm CL through sequential molts, and results can be used to fill a gap in current growth models.

Bioturbation of mangrove sediments by Uca uruguayensis (Nobili, 1901) and U. rapax (Smith, 1870) was compared based on the grain-size composition and organic content in surface sediment around the burrow and feeding pellets in two mangrove zones of the São Vicente Estuary, state of São Paulo, Brazil. For each species, 25 burrows with active crabs were selected. All pellets within a 15-cm radius of each burrow were carefully collected; samples of substrate were taken; and the crab occupant was excavated, sexed, and measured for carapace width (CW). The number of spoon-tipped setae on the second maxilliped of each species was estimated; U. uruguayensis showed more of these setae than U. rapax. For both species, the sediment post-processed by feeding activity (feeding pellets) showed a similar increase of coarser fractions and a smaller organic content. However, U. uruguayensis was more efficient in removing organic matter (88.1%) from the sediment than U. rapax (37.5%). These results suggest that different numbers of spoon-tipped setae on the second maxillipeds of the fiddler crabs do not affect the potential for grain-size selection, but result in differing abilities to remove organic matter from the sediment.

The genus Dolops is one of only four genera in Branchiura, and as most other members of the group it is also ectoparasitic on freshwater fish. The large majority of investigations of the genus concern the single species of Dolops found in southern Africa, D. ranarum, although most of the remaining species are found in South America. In this paper, we present the first morphological description of the larva of D. carvalhoi using light- and scanning electron microscopy. This is the first detailed account of the larvae of any non-African species of Dolops, and our comparison of the larvae of D. carvalhoi and D. ranarum based on literature data show them to be surprisingly alike. The general implications of these findings are discussed in a phylogenetic context, with special emphasis on the different larval types found in the other genera of Branchiura.

The holarctic amphipod Diporeia spp. was historically the most abundant benthic macroinvertebrate in the offshore region of the Laurentian Great Lakes basin. However, since the 1990's, the numbers of Diporeia have declined precipitously throughout the region. Competition for food with introduced dreissenid mussels may be partly to blame for this decline. Thus, a better understanding of how Diporeia responds and adjust to starvation is needed. For this purpose, we used liquid chromatography (LC) coupled with time-of-flight mass spectrometry (TOFMS) to study the metabolite profiles of Diporeia during starvation. Diporeia were collected from Lake Michigan, brought to the laboratory and starved for up to 60 days. During the starvation period, metabolite levels were determined at 12-day intervals and compared to those of day 0. Principal component and cluster analyses revealed differential abundance of metabolite profiles across groups. Significantly down-regulated metabolites included polyunsaturated fatty acids, phospholipids, and amino acids and their derivatives. Overall, starved organisms relied predominantly on glycerophospolipid metabolism and protein based catabolism for energy production. This research demonstrates that LC-MS based metabolomics can be used to assess physiological status and has shown that unique metabolite profiles are distinguishable over several weeks of starvation in this freshwater amphipod. More importantly these unique metabolites could be used to gain insights into the underlying cause(s) of Diporeia's decline in the Laurentian Great Lakes.

Sperm and spermatophore production in Callinectes danae Smith, 1869 were examined by histochemistry and correlated with gonadosomatic (GSI) and hepatosomatic (HSI) indices. The GSI from developing (DE) and mature (MAT) males increased while the HSI decreased from DE to MAT, demonstrating that the maturation of the male reproductive system requires resources from the hepatopancreas. No histological or histochemical differences were observed between DE and MAT except for the larger amount of secretions produced in MAT. Spermatogenesis occurs in the seminiferous lobules surrounded by accessory cells. Each lobule is filled with cells at the same developmental stage. Spermatid maturation is characterized by an increase in the metachromatic acrosome. Sperm are released into seminiferous ducts, which moves them to the vas deferens divided into anterior (AVD), median (MVD), and posterior (PVD) regions. Spermatophore formation begins at the anterior part of AVD; sperm masses are separated and compacted in small packets by a basophilic and alcianophilic secretion. Small amounts of eosinophilic secretion, positive for proteins and neutral polysaccharides, are added around the sperm initiating the formation of the spermatophore wall. Mature round spermatophores are found in the posterior part of AVD and present a thick glycoproteinaceous wall, surrounded by acidic polysaccharides. The spermatophores are stored in MVD without size difference from DE to MAT. The MVD is filled with a granular secretion composed of glycoproteins. The secretion in PVD is fluid and homogeneous, facilitating the transference of the spermatophores. In conclusion, the hepatopancreas is related to the maturation of the male reproductive system in C. danae. DE males presented all histological conditions to fertilize females as MAT males, but the decrease in HSI and increase in GSI indices correlated with the vas deferens indicate that reserves are necessary to produce large amounts of seminal fluid in MAT males.

Both sexes of Laophontodes macropodia Gee and Fleeger, 1986 (Ancorabolidae, Laophontodinae) are redescribed in detail based on type material from the South Orkney Islands and other material from King George Island (South Shetland Islands). The species is fixed as the type of a new genus Calypsophontodes on account of the sexually dimorphic setation on enp-2 of P4 (inner seta present in female, absent in male) and the sexual size dimorphism in P2–P4. The taxon further displays a number of plesiomorphic characters, such as the presence of an outer spine on enp-2 of female P3 and the protruding endopodal lobe in female P5. Laophontodes latissimus Brady, 1918 is regarded as species inquirenda within Calypsophontodes. The geniculation of the outer seta on exp-2 of P1 and the presence of an outer bump with long spinules on the second antennular segment are proposed as potential synapomorphies of Laophontodinae (including Ancorabolina).

A new bathynellacean, Indobathynella prehensilis n. gen., n. sp., is described from farm bores in southeastern India. This is an aberrant species, possessing such a unique combination of plesiomorphic and apomorphic characters that it cannot be assigned outright to any of the three known families of the order Bathynellacea, viz., Bathynellidae, Parabathynellidae, and Leptobathynellidae. And yet, it is provisionally placed in Bathynellidae pending reconstruction of the phylogenetic relationships within Bathynellacea. This decision is based mainly on the following plesiomorphies: 1) antennule is 7-segmented; 2) antenna has exopodal segment; 3) mandibular palp is 3-segmented; and 4) male thoracopod VIII has a basal penile lobe. The new taxon also displays some close apomorphic affinities with Parabathynellidae such as a 3-segmented prehensile maxilla, a lobe-like female thoracopod VIII, and a 1 -segmented pleopod I. The other spectacular apomorphies of the new species, some of them suggesting its possible neotenic origin, are unique to Bathynellacea as a whole, and these include: 1) antenna is 4-segmented, with extremely reduced armature; 2) gnathobase consisting of 5 distinct teeth is fused with the first segment of mandibular palp; 3) thoracopods I–VII have 2-segmented exo- and endopod, except for 3-segmented endopod on thoracopod I, and with only a single endopodal seta on thoracopods II–VII; and 4) male thoracopod VIII is greatly reduced and uncinate, with exopod being fused with basis and having only two setae. All in all, the new taxon seems to be a crucial phylogenetic link between Bathynellidae and Parabathynellidae. A note on the ecology and biogeography of the new species is also added.

The bathypelagic shrimp genus Pasiphaea Savigny, 1816 (Caridea: Pasiphaeidae) has been previously known from Taiwan from only three species. However, recent deep-sea surveys around the island have collected numerous specimens comprising ten species, of which four are new to science: P. aequus n. sp., P. alcocki (Wood-Mason and Alcock, 1891), P. exilimanus n. sp, P. falx n. sp., P. japonica Omori, 1976, P. mclaughlinae Hayashi, 2006, P. levicarinata Hanamura, 1994, P. orientalis Schmitt, 1931, P. sirenkoi Burukovsky, 1987 and P. taiwanica n. sp. The four new species are fully described and illustrated, and compared with allied congeners. Pasiphaea orientalis is redescribed, as this species is endemic to Taiwan and its original description is inadequate. Amongst the three new records of Taiwan, P. levicarinata is also recorded for the first time from the northwestern Pacific.