The rates of exchange of sodium and water and renal filtration rates were measured in field populations of Birgus latro (Linnaeus, 1756) in rain forest on Christmas Island, Indian Ocean. Water exchange was quite high (47.7 ml·kg⁻¹·d⁻¹) and on seed diets must have been derived largely from drinking, although animal tissue when eaten would have provided a greater amount of preformed water. Under prevailing conditions water output was chiefly in the excretory fluid. Intake of sodium was almost entirely from the food, and the mean rate of exchange of sodium (7.8 mmol·kg⁻¹·d⁻¹) was too high to be satisfied from vegetable origins. The crabs clearly fed regularly on animal material, probably Red Crabs, Gecarcoidea natalis. The bulk of sodium loss occurred via the excretory fluid. The intakes of water and sodium are well above the minimum level required for the maintenance of salt and water balance and, under field conditions with access only to rain water for drinking, B. latro has a very considerable reserve of osmoregulatory capacity. Saline drinking water is not required for the maintenance of ion balance.

Methyl farnesoate (MF) was identified for the first time in the hemolymph of Nephrops norvegicus from Mediterranean deep-sea waters (around 500 m) by gas chromatography-mass spectometry and quantified by liquid chromatography. The MF was present in females as well as in males, although no clear-cut differences between sexes were observed. Levels of MF found in the hemolymph of intact animals were 0.5–1.0 ng/ml irrespective of the sex. Although the observations are still limited, females showed oscillations in MF that seem to parallel the vitellogenic cycle. Eyestalk ablation, in both males and females, caused a 10-fold increase in MF hemolymph levels.

The redclaw crayfish, Cherax quadricarinatus, is of commercially important interest, but its digestive capabilities are not yet completely understood. The understanding of how its digestive enzymes operate can help in the formulation of better diets for this species. A range of digestive enzymes (proteases, carbohydrases, and lipase) was found in the midgut gland and gastric fluid, with activities generally higher in the gastric fluid. Total protease showed maximal activity at pH 7.0–7.5 in both midgut gland and gastric fluid and was inhibited by 1.5 mM CuCl₂ and 10 mM phenylmethylsulfonyl fluoride (PMSF). On the other hand, protease was activated by 1.5 mM CaCl₂. Trypsin-like activity showed pH optima at 7.0 in both the midgut gland and the gastric fluid and was activated by 1.5 mM CaCl₂, FeSO₄, and Na₂SO₄. Chymotrypsin-like activity and carboxypeptidase A-like activity showed higher activities in the gastric fluid. Carboxypeptidase B-like activity showed optima at pH 6.0 and 7.0 in both the midgut gland extract and the gastric fluid, respectively. Leucine aminopeptidase was detected at low concentration. The α-amylase (optimum pH 6.0) was inhibited by 1.5 mM CuCl₂ and 5 mM citric acid. A significant increase in the α-amylase activity was observed when it was pre-incubated in the presence of 15 mM CaCl₂. Cellulase and laminarinase activities were readily detected. Other p-nitrophenyl glycosidases were also detected in the gastric fluid and the midgut gland. Lipase was detected only in the gastric fluid. The presence of these enzymes is an indication of the ability of this species to digest a wide range of food components.

Ultrastructural changes of the compound eyes were compared in Ocypode species living under different daylight and annual rhythms near the equator (O. ryderi, O. ceratophthalma), in the northern (O. cursor) and in the southern hemisphere (O. quadrata). Independent of geographical latitude, the eyes of these Ocypode species undergo daily changes in morphology. Throughout the day the rhabdomeric diameter is small. A massive increase of rhabdom diameter occurs at dusk; a breakdown phase starts during the second half of the night. Before dawn the rhabdom size is near to that during daytime and seems to be prepared for the day-state. Besides the rhabdom, the size of the palisade-ER and the position of pigment granules and mitochondria within the retinula cells change. In all investigated Ocypode species the rhabdom turnover is influenced by different light and dark regimes. During extended darkness, rhabdom diameters resemble those of day-adapted animals. Extended exposures to light cause no or little change in rhabdom diameters of O. ryderi, but in O. ceratophthalma and O. quadrata rhabdom diameter of both distal and regular retinula cells grows up moderately. During the following dark adaptation the rhabdom diameter increases dramatically in the regions of both distal and regular retinula cells of O. ryderi. In O. ceratophthalma and O. quadrata the diameter of regular retinula cells doubles. If the crabs are kept under darkness during the day, the rhabdomeric diameter grows moderately but never reaches the diameter of the night-adapted state. If the crabs are brought into bright light during the night, rhabdom diameters decrease to that of day-adapted animals. Independent of different geographical habitats, in these Ocypode species rhabdom synthesis seems to be stimulated above all by the onset of darkness, whereas rhabdom diminution during the night seems to be controlled endogenously.

Despite their prevalence in headwater streams, crayfish are largely ignored in most leaf decomposition studies. We conducted a field survey in 30 pools along a headwater stream to document the biomass of various shredder invertebrate species and subsequently compared their leaf processing and particulate organic matter (POM) production rates in a laboratory experiment. The crayfish Paranephrops zealandicus dominated the shredder functional feeding group, comprising 99% on average of the total biomass of shredder invertebrates. This was followed by the stonefly Austroperla cyrene, which made up only 0.62%. A laboratory experiment, using stoneflies and two size classes of crayfish, showed that processing rates of large crayfish (normalised by body weight) were lower than those of small crayfish and stoneflies. However, large crayfish had the greatest impact on leaf decomposition and POM production. It is their large body size and dominance of invertebrate biomass that determines the significance of crayfish as shredders. Given their widespread distribution in New Zealand and elsewhere, crayfish may play key roles as shredders in many headwater streams, especially where shredder insect diversity/abundance is low.

The activity of visual systems is known to affect development of the neural tissue associated with vision in both vertebrates and invertebrates. Three species of crayfish were compared for variations in the gross structures of the eye and of the underlying neural tissue of the optic system that were associated with environmental adaptation. The troglobitic crayfish Orconectes australis packardi and two epigean crayfish, Cambarus tenebrosus and Procambarus clarkii, were used. Cambarus tenebrosus raised in the cave are functionally blind although ommatidia develop, indicating that the primary sensory structures still develop without normal input. Troglobitic crayfish have lost the genomic ability to form a functional visual system. Electrophysiological records from neurons within the optic stalk of O. australis packardi showed no response to light. The neuronal ganglia within the eye stalk of C. tenebrosus are disorganized which could be the reason for the lack of a behavioral response related to sight. Second order neurons associated with olfaction arise in the central brain and send processes to lobula within the eye stalk via the protocerebral tract. Cross sections of this tract revealed that the troglobitic crayfish have more olfactory projection neurons and fewer large axon profiles than the other two crayfish, suggesting that O. australis packardi has more neural processing devoted to olfaction as an adaptation to cave life.

Female Porcellio laevis (Latreille) raised in the laboratory first reproduced when 7 months old and can breed up to 7 times during their life time irrespective of season. In that, this species differs from most other isopod species studied so far. After a single mating, a female can breed several times without the presence of a male presumably because she stores sperm. Females known to be virgins never became gravid, thus there is no evidence of parthenogenesis. Males are therefore essential for reproduction in P. laevis. Sex ratio in the laboratory population was found to be 1 male to 2.5 females. The average time intervals between consecutive broods is 7.7 weeks. Most females reproduce 3 or 4 times in their lifetime (e.g., until the age of about 1 year). The average number of broods is 3.1. Number of mancas in the brood is positively correlated to weight of the mother. The average number of mancas in a brood is 66.6. The average survival of mancas until they are 7 or 8 months old is 44.7%. The ovary of P. laevis is typical of an iteroparous isopod in that it contains both large and small oocytes. However, it differs from that known for all other isopod species by having a few large oocytes persisting in the ovaries at all times. Apparently, oocyte cohorts do not mature simultaneously as indicated by the fact that some large oocytes were present at all times but move a few at a time into the brood pouch at a continuous rate.

Typically ≥90% of the eggs in clutches fertilized by hardshell Prince William Sound Lithodes aequispinus males ≥107 mm carapace length initiated division. Golden king crab males with only one chela and those with post-molt carapaces ≥11 days old were effective parents. Some test males had exclusive access to three ripe females. Their first and second mates all produced viable clutches with 81–100% of eggs exhibiting development. Not all males induced a third female to ovulate. The percentage of eggs initiating division in the clutches of their third potential female mates ranged from 56 to 100%.

Lysmata debelius is a territorial species, characterised by forming long-term pair bonds between individuals. This species is popular in the aquarium trade, and although it has culture potential it is not yet raised on a commercial scale. These coral reef inhabitants are considered to be key species in the natural habitat, and their culture is of conservation interest. One of the main causes of death in captivity is due to a disturbance of the pair bond, which results in one individual killing the other. However, the factors that induce this behaviour are not understood. A three-chambered apparatus was constructed to test binary individual recognition. One individual from a pair and one outsider (a stranger), both in similar reproductive state and size, were placed in different chambers. The other individual of the pair was placed in the remaining space, and its behaviour continuously recorded with a video camera during 3 h. The number of visits and the total time spent in the chamber of its mate over a 30-min interval, analysed with a two-way ANOVA, were significantly higher than for the time spent in the stranger's chamber. These results suggest that Lysmata debelius is able to distinguish a partner from a stranger, and this ability appears to remain for at least 3 h after separation.

Hermit crabs depend on gastropod shells that influence many characteristics of their life histories. The relationship between shell utilization patterns and biological attributes enables comparisons among populations and discussions of the influence of the environment (shell supply) on hermit crab biology. This study was undertaken in a cobble/boulder low slope rocky shore in Grande Beach, São Sebastião, São Paulo State, Brazil. Crabs were randomly sampled, measured (shield length), and their sexes were determined. Shells were identified, sized (height, width, and aperture length), and weighed. Four hermit crab species were registered: Clibanarius antillensis, Paguristes tortugae, Pagurus criniticornis, and Calcinus tibicen. Shell use was influenced by shell availability, despite the selection of certain shell types and sizes by hermit crabs. Shells were not considered a limiting resource to this hermit crab assemblage, and shell availability was dependent on shell type and size as well as on individual size and species composition of the hermit crab assemblage (presence of competing species). Shell partitioning among crab species was recorded and associated with species coexistence in this area. Differential shell use was recorded among size and reproductive classes of C. antillensis. There was a tendency toward high numbers of ovigerous females in relatively lighter (smaller) and small-aperture shells, such as Cerithium atratum and Morula nodulosa, which was associated with growth restriction and low fecundity imposed by shell morphology.

Prevalence of certain celestial and terrestrial cues was tested in the zonal recovery behavior and orientation of the fiddler crab Uca cumulanta. Experiments were conducted in the field bordering a mangrove forest on the eastern Venezuelan coast. Uca cumulanta exhibited zonal recovery behavior based on different orientational references, including celestial cues (sun and polarized sky light) and terrestrial cues (landscape vision and substrate slope). Sun azimuth orientation was time-compensated. Apparent solar position and polarized sunlight pattern were celestial cues which, as tested, prevailed over landscape references and beach slope—terrestrial cues—in cueing the direction of the orientation response shown by crabs.

The spatial and seasonal distributions of Callinectes danae Smith, 1869, in Ubatuba Bay, São Paulo, Brazil, were investigated as a part of a broad study on the general biology of portunids along the northern coast of São Paulo State, Brazil. Swimming crabs were collected during one year, from September 1995 to August 1996, along eight transects determined according to local physiographic features. Three replicate trawls were performed monthly at each transect. Depth, salinity, dissolved oxygen, temperature, organic matter content, and texture of the sediment were measured. Callinectes danae individuals were concentrated in shallow water close to the discharge of estuaries where the bottom is composed of fine and very fine sand. The species was more abundant in the warmer months. During the study period, C. danae exhibited continuous reproduction with a peak of reproductive intensity in June. Within this area, some sites are particularly favorable for C. danae establishment due to a combination of factors and prevailing local conditions.

In this study, eight species of Epistylis were observed attached to the cuticular surface of 13 body parts of crayfish Cambarellus patzcuarensis. The species found were E. bimarginata, E. branchiophila, E. carinogammari, E. gammari, E. lacustris, E. niagarae, E. stammeri, and E. variabilis. Some morphological structures of the species observed with optical and scanning electron microscopy are presented. The distribution of each species over the exoskeleton, as well as the occurrence, was recorded for each decapod studied. Specific richness and G tests were calculated for all body parts. Epistylis gammari was the most widespread species on the surface of C. patzcuarensis, being attached to the 13 body parts studied. Seven body parts harboured eight species while the gills supported only one species. Epistylid species did not show any preference for a particular body region but rather utilized the substrate available, and every body part plays an important role as a substrate; this is consistent with the value obtained from the G test. Epistylid species are already considered as epibionts without host or body region specificity.

Artemia is not believed to be a selective filter-feeding organism; however, evidence of an influence of the size of the nutrient particles on the filtration process of this crustacean is presented. To evaluate the influence of the size of food on the filtration process, assays with latex particles and with starch granules were made. A relation between the frequency distribution of size of the particles found in the digestive tract of the animals and the frequency distribution of size of the particles found in the medium is shown. The results indicate that Artemia has a preference for food of specific size. The behavior of different size-classes of animals analyzed is shown, but I conclude the size of food for Artemia must range between 6.8 and 27.5 µm, with the optimum about 16.0 µm.

A new cirripede (Verrucomorpha: Verrucidae) Verruca digitali Buckeridge sp. nov. is described from the late Miocene in Orange County, California. The discovery of dozens of specimens in siliceous shale of the upper Monterey Formation is remarkable because both living and fossil Verrucidae are rare in the Northeast Pacific and adjacent terranes and the stratigraphic sequence is characteristically bathyal in origin. We propose that these specimens of V. digitali were epiphytic, being attached to seaweed that was either planktic or uprooted and displaced downslope. This species is similar to Verruca alaskana Pilsbry, a Pliocene species from Alaska, and Verruca laevigata Sowerby, an extant species inhabiting shallow waters off the west coast of South America. Verruca digitali is a likely Miocene candidate for a “Verruca laevigata bioseries.”

An epizoic stalked barnacle, Octolasmis angulata, was identified within the branchial chambers of Charybdis callianassa, a swimming crab from Moreton Bay, Queensland, Australia, making this crab a new host for O. angulata. In the present study fifty-two crabs, 30–49 mm carapace width, were dissected, and thirty-three were found to have the epizoite. The number and position of the O. angulata within the branchial chambers were noted. Octolasmis angulata is principally found attached to the cuticle of the anterior chamber wall in the epibranchial space, although attachment to the gills does occur. Charybdis callianassa is also parasitized by the sacculinid barnacle Heterosaccus lunatus, and one such parasitized crab contained eighty-seven O. angulata, the highest number recorded in the present study. The factors governing O. angulata distribution within the branchial chambers of C. callianassa are discussed.

The adult of Scalpellopsis striatociliata and the ontogeny of its capitular and peduncular plates are described. During ontogeny, S. striatociliata develops the carino-lateral (CL) and inframedian (L2) plates heterochronously after some peduncular plates (cl), which is unique. The position of Scalpellopsis as sister-group of the other scalpellids is reaffirmed. The Scalpellidae have diverse peduncular plate patterns, with the 8-plated pattern being ancestral and the most widespread among the genera. The peduncular plate patterns of several species of Scalpellidae are presented.

The nannastacid cumacean, Normjonesia danieli, n. g., n. sp., is described from a depth of 88 m on the Southwest Florida shelf in the southeastern Gulf of Mexico. The new genus appears to have its closest affinities with Campylaspis Sars and Cubanocuma Băcescu and Muradian, also known from the shallow waters of the Caribbean Sea. A combination of characters, including: (1) the apparent lack of terminal aesthetes on antenna 1; (2) the absence of exopods on the female; (3) the presence of 5 pairs of exopods on the male; and (4) the presence of long terminal setae on the third maxilliped, distinguishes Normjonesia from the other known genera of the family Nannastacidae.

A new species of amphipod crustacean (Acanthonotozomellidae) from the deep-sea of the Drake Passage is described in detail. Its main characteristics that are unique for this species are: slender dorsal carinae on pereon on pleon; small cuticular teeth all over the dorsal surface, the carinae and the coxal plates; coxa 1 with deeply excavate apex.

A new species of ingolfiellid Amphipoda, Ingolfiella beatricis, collected from groundwater in a cave near Ljubljana in Slovenia is described. It is the first ingolfiellid, possessing developed “ocular lobes”, found in inland fresh groundwater and is therefore of biogeographic interest. Its morphological characters suggest a marine origin, a supposition that is strengthened by the marine relationships of accompanying fauna.

The present work provides a first description of the zoeal stages of the Caridean prawns Campylonotus vagans, C. semistriatus and C. capensis Bate, 1888. Zoeal stages one and two were obtained from plankton catches during several expeditions in the Magellan region and the southwestern Atlantic Ocean, and first zoeae of C. vagans were confirmed with larvae hatched in a laboratory culture. Based on the results obtained, we conclude the morphological differences of the presence/absence of carapace spines, the shape of the somites, the telson and its number of posterolateral spines to serve as diagnostic features for the determination of campylonotid larvae. Morphological comparisons with larvae of the Pandalidae, Palaemonidae, and Oplophoridae suggest the Campylonotidae to be phylogenetically related to the Oplophoridae. Additionally, a key for identifying the zoeal stages of the Campylonotidae from the southernmost region of America is given in order to facilitate future ecological and life history studies.

Heteropolyonyx, new genus (type species: H. biforma new species), is established on the basis of the presence of transverse ridges on the cervical regions of the carapace and the telson being divided into five plates, characters quite different from its related genera Polyonyx Stimpson, 1858, and Eulenaios Ng and Nakasone, 1993. The male/female pair of H. biforma was found in a tube of an unidentified polychaete of the genus Chaetopterus. Polyonyx utinomii Miyake, 1943, is redescribed from the holotype specimen and recently obtained material from Japan and the Maldives. This species is readily distinguishable from the other Indo-West Pacific species of Polyonyx by the carapace and chelipeds covered with numerous transverse and oblique striae on the dorsal surface and the meri of the chelipeds having a very large, broadly rounded lobe on the dorsoflexor margin. The present record of P. utinomii from the Maldives is the first report outside Japan and greatly extends its geographical distribution westwards into the Indian Ocean.

Previously undescribed fossil material from the late Eocene Hoko River Formation and the Oligocene Makah Formation, Olympic Peninsula, Washington, provides new insight into the evolution and biogeography of five families of decapod crustaceans. New taxa include Homola vancouverensis, Xeinostoma? antiqua, and Daldorfia himaleorhaphis. New material makes it possible to provide a complete reconstruction of the dorsal carapace of Macrocheira teglandi, and a possible juvenile Branchioplax washingtoniana is described for the first time. The range of the genus Homola, known in modern oceans, has been extended into the late Early Cretaceous, and the occurrence of that genus in rocks of the Pacific coast of North America marks the first authentic report of the Homolidae from that region. The Cyclodorippidae is now known to have inhabited the Pacific coast of North America as early as the late Eocene. The geologic range of the genus Daldorfia now extends into the Oligocene, and its earliest known occurrence is from rocks of Washington, U.S.A.

Two brachyuran crabs collected at Socotra Island (Republic of Yemen) in the northwestern part of the Indian Ocean turned out to be conspecific with Sphaerocarcinus bedoti Zehntner, 1894, so far only known from a single female collected at Amboina, Indonesia, without any information on its ecology. Based on the new material and especially the availability of a male for comparison of the morphology of the copulatory appendages (gonopods), Sphaerocarcinus Zehntner, 1894, is synonymised with Caphyra Guérin, 1832. The extremely convex and globose carapace shape of the type specimen from Amboina turned out to be atypical and possibly caused by parasitic infection. Ecologically, C. bedoti, like most species of the genus Caphyra, lives epibiontic on soft corals (Octocorallia: Alcyonaria).

Macrophthalmus boteltobagoe (Sakai, 1939) is shown to be specifically distinct from M. holthuisi Serène, 1973. The two species differ in many morphological characters and, as well, are shown to prefer different habitats—M. boteltobagoe lives in holes in limestone and scrapes algae for food, whereas M. holthuisi lives on soft mud around mangroves and is a sediment feeder. These different feeding strategies are reflected in the structure and setation of the claws, and in the conformation of the gastric mills.