Nauplii of the anostracan Chirocephalus ruffoi were grown until sexual differentiation under standard laboratory conditions (18 ± 1°C temperature; 12L/12D photoperiod; 1600 lux intensity; 200 individuals L⁻¹ density) and fed algae (Selenastrum capricornutum), baker's yeast (Saccharomyces cerevisiae), or a lipid-enriched yeast (Lansy PZ). In parallel experiments, we evaluated survival, development, and increase in body length and weight (wet and dry). Differences among the treatments were analyzed by ANCOVA and Newman-Keuls multiple range tests. The length-weight growth data, log-transformed, were fitted using an orthogonal least squares method. The results show that food type has marked effects on the growth rate and survival of the animals. As previously shown in terms of nutritional effectiveness, enriched yeast produces the best culture results.

Moina hutchinsoni Brehm, 1937, a nearctic anomopod cladoceran, was observed in shallow ephemeral ponds of the former Texcoco Lake, near Mexico City, Mexico. The type material, from Lake Winnemucca, Nevada, was considered lost; additional topotypic material could not be obtained from that locality because the site is completely dry. The species is redescribed herein based on specimens from Texcoco Lake and Border Lake, Nebraska. Specimens from these localities were compared to study the morphological variability of this species; differences were found in the cuticular hair patterns on head, body, antennules, and second antennae, in the number of feathered setae on the postabdomen, and in the structure of pectens in claws. The life cycle of this rare species was analyzed in the laboratory. In culture, diet consisted of the microalgae Ankistrodesmus falcatus (freshwater) and Chlorella sp. (marine); both algae were consumed by the cladoceran. Culture temperature ranged between 15° and 20°C, and salinity range was 5–25 g L⁻¹. Cultured specimens were significantly larger than those from field populations. Lower temperatures correlated with a delayed first reproduction and with a longer inactive time between succeeding clutches. The wide thermal and salinity ranges tested during culturing, plus the ability of these animals to consume algae not normally found in its natural environment, suggest a euryecious character of this species in laboratory conditions that contrasts with the affinity of natural populations for high-salinity habitats. The lifespan of this species is longer than that of other moinids; it may be the longest-lived species within the Moinidae. The average clutch size ranged from 12 to 24.8 neonates; optimal environmental conditions differed for number of neonates and maximum clutch size. Loss of the natural environments (saline lakes) where this rare species has been recorded, both in Mexico and U.S.A., suggests an endangered status of this cladoceran.

The recent renewed interest in the Indian stygofauna has led to the discovery of another interesting copepod representative, from the almost exclusively marine family Diosaccidae Sars, 1906. Neomiscegenus n. gen. and Neomiscegenus indicus n. sp., from the subterranean freshwaters of the Krishna River at Vijayawada, Andhra Pradesh, are described. The new genus belongs to that evolutionary line of Diosaccidae that encompasses the genera Amphiascoides Nicholls, 1941; Paramphiascella Lang, 1948; Paramphiascoides Wells, 1967; and Miscegenus Wells, Hicks, and Coull, 1982. The genus Miscegenus has the highest number of synapomorphies with Neomiscegenus, including the shape of the caudal rami and the armature formula of the swimming legs. A peculiar shape of the genital field in the female and the armature of the antennal exopod in both sexes are the most important autapomorphies of the new genus, while the fine structure of the sexually dimorphic second leg in the male is probably plesiomorphic. The phylogenetic position of the new genus is briefly discussed.

We investigated the functional significance of intersexuality in the amphipod Corophium volutator, a key species in soft-bottom intertidal communities. Intersexes in this species possess morphological and anatomical characters of both males and females. Two broad types of intersexes were identified: those with nonsetose oostegites and two penial papillae (Type I), and those with setose oostegites and one or two penial papillae (Type II). We found little evidence that intersexes function as females, but some females housed experimentally with intersexes became ovigerous, indicating that intersexes can function as males. Females that mated with Type II intersexes produced smaller broods than those that mated with Type I intersexes or males, suggesting that this form of intersexuality may be costly to amphipods (most Type II intersexes possessed only a single testis). Male function of intersexes may be important in populations of C. volutator because males are frequently the limiting sex due to extremely female-biased sex ratios.

An immunological approach was used to elucidate whether trypsin is synthesized and stored as trypsinogen in the midgut gland of the shrimp Litopenaeus vannamei. Two peptides were constructed using sequences deduced from known shrimp genes: trypsinogen activation peptide and an internal sequence. These peptides were used as haptens to elicit antibodies in rabbits. Specific antibodies were used to detect trypsinogen by Western blot and in histological sections of the midgut gland. Trypsinogen was found by Western blot and was localized into the midgut gland B cells by using immunohistology. In fed shrimp, trypsinogen associated with food particles was found in the lumen of the midgut gland tubules as well. Our results show that regulation of shrimp trypsin activity is similar to that of frequent feeder species, in which trypsin is stored as a zymogen, waiting for secretion and activation.

Sexual maturity, temporal reproductive pattern, and recruitment of juveniles were examined for the shrimp Rimapenaeus constrictus at three different bays in the Ubatuba region (Mar Virado, Ubatuba, and Ubatumirim), State of São Paulo (23°S 45°W). Monthly samples were taken from January 1998 to December 1999. The presence or absence of mating plugs (associated with mating and insemination) and ovarian maturity were used to examine breeding in adult females. The whole sample comprised 3863 females and 1468 males. Estimates of size (carapace length) at the onset of sexual maturity were 7.0 mm and 7.8 mm for males and females, respectively. Higher percentage of females bearing ripe gonads was observed during spring and summer over the course of the study, contrasting to the low proportion in fall 1998 and winter 1999. Juvenile shrimps were sampled year-round. These results suggest a continuous reproductive pattern for R. constrictus. Mating, spawning, and juvenile recruitment took place mostly in shallow waters up to 20-m depths in the study region. Warm to mild temperatures may favour the spawning pattern observed in this species. The classical paradigm of continuous reproduction at lower latitudes, with increased seasonality of breeding period at higher latitudes, seems to apply to this species.

The locomotor rhythmicity of the Norway lobster Nephrops norvegicus was studied under constant conditions of darkness in individuals collected on the continental slope (400–430 m). Periodogram analysis revealed the occurrence of both circadian (of around 24 h) and ultradian (of around 12 and 18 h) periodicities. Form estimate analysis of the circadian and ultradian time series revealed the occurrence of significant peaks of activity during the expected night phase of the cycle and day-night transitions, respectively. No ultradian locomotor activity rhythms have been reported in previous studies on continental shelf N. norvegicus, suggesting that this phenomenon may be limited to deep-water animals. A discussion is presented to account for the occurrence of the mechanism of ultradian rhythms when there is significant environmental light intensity reduction, as on the continental slope, where the species attains its maximum densities in the western Mediterranean.

Larval stages and the megalopa of Pachycheles serratus are fully described and illustrated on the basis of laboratory-reared materials collected from Margarita Island, Venezuela. Complete development of P. serratus includes two zoeal stages and the megalopal (decapodid) stage, cultured at a water temperature of 25°C and salinity of 37‰. The first zoea lasts 5–6 days and the second lasts 8–10 days. A diagnostic character of the present species is the existence of a short mesial spine on the maxillular endopodite, unique among known zoeae of the genus Pachycheles. In addition, they can be distinguished from the first zoeae of P. laevidactylus and P. monilifer (western Atlantic congeners for which larval morphology is well-described) by size and ornamentation of the rostral spine, disposition of lateral spines on the abdominal somites, and setation of the maxilliped 3 in the second zoea. A comparative summary of zoeal morphology is provided for members of the genus Pachycheles.

Ovigerous females of Aegla uruguayana were observed in the laboratory during the egg incubation period, under controlled conditions. Hatching of juveniles was characterized by a high degree of asynchrony and ranged from three to four days for most females. Maternal care of juveniles was also seen. During the first day after hatching, juveniles remained living on the ventral side of the abdomen of females, while during the second and third days they were able to explore the surroundings next to the female body, finally separating from her on the third or fourth day of life. No special structures in juveniles for attaching to females were seen. Both the asynchronous hatching and maternal care in A. uruguayana were in many aspects closer to similar processes observed in freshwater astacoid crayfishes than to the ones observed in other anomurans, being the way in which juveniles of A. uruguayana are linked to their mothers, as well as the absence of moulting while they remain with their mothers, which are similar to processes reported for freshwater brachyuran crabs.

Exploitation rates for legal-sized (> 159-mm carapace width) male Dungeness crabs, Cancer magister, often reach 90% in the northern California fishery, thus making large male crabs scarce and possibly reducing mating success particularly among large (> 140-mm carapace width) female crabs. Relying on known laboratory molting and presumed mating, we characterized temporal changes in proximal sperm plugs of female C. magister from four days through 323 days following molting and mating. Although sperm plug surface area decreased steadily with increased days following mating, we found that complete sperm plugs and/or sperm plug remnants were present through approximately 180 days post mating, a period exceeding the approximately four month duration of the mating season for Dungeness crabs in northern California. Based on dissection and identification of sperm plug presence, we assessed mating success of female Dungeness crabs at two locations in northern California during June and July 1997, following the February-May mating season. Among 590 female crabs (87–167-mm carapace width) classified as having definitely molted on the basis of shell condition observations, we found that 93% had complete sperm plugs or remnants of sperm plugs in vaginal tracts. Among the 336 large (> 140 mm) definitely molted female crabs, sperm plug presence was 98.5%. Thus, despite the intense fishery on large male Dungeness crabs, sperm plug data provide evidence of essentially 100% mating success among large female crabs that molted during 1997.

The soldier crab Mictyris brevidactylus Stimpson inhabits sandy flats of Southeast Asia. The crabs that we studied fed on deposited matter in the surface sand in two ways. On well-drained sand in the upper part of their habitat, they usually made a single tunnel roofed with sand to conceal themselves while they fed. After feeding, they returned to an ascending shaft from which they had earlier emerged. Then, they descended via the plugged ascending shaft and transformed the shape of the shaft into an ovoid air chamber at a sufficient depth. During the daytime low tide, on the waterlogged, fluid sand near the shoreline, large individuals, mostly males, fed in droves on the surface while moving along the shoreline as it moved with the tide. After feeding for about 2 h, they made a small air chamber slightly above the shoreline by using corkscrew-style digging, and descended into the semi-fluid sand. During the night-time low tide, the crabs fed separately for about 4 h on both the fluid sand near the shoreline and the well-drained firm sand in the upper habitat, and retreated into the sand, although they took longer to retreat into the well-drained sand than into the semi-fluid sand. That is, the crabs feeding on the surface at the daytime low tide returned to the subsurface-feeding area and made a small air chamber during the night-time low tide. Later, at low tide, the small air chamber was elongated to allow subsurface feeding. We consider that the movement to the upper habitat at night-time and the feeding near the shoreline in the daytime help the crabs evade predators that rely on sight, such as birds.

This study quantified the burrow dynamics of the gecarcinid land crab Gercarcoidea natalis (Pockock, 1888), the most common land crab in rain forest on Christmas Island, Indian Ocean. Mean burrow density remained relatively stable over a two-year period, fluctuating between 1.4 and 1.6 burrows/m². Burrows were long-lived, stable structures, with a mean turnover time estimated at least 4.4 ± 1.6 y, and probably greater than 5 y. Burrow entrances were also highly stable in space. Two thirds of burrow entrances were repositioned within an area of 20 cm² or less, and 83% of entrances moved within less than 60 cm². Red crabs accumulate litter around their burrow entrances and create nutrient hotspots in the soil around burrow entrances, whose stability and longevity suggested that germinating seedlings may derive some benefit from germinating in the immediate vicinity of crab burrows. The rate of burrow turnover is slow, causing minimal soil disturbance at the study site with little, if any, impact on above-ground plant productivity. Red crabs plugged their burrows intermittently year-round with loose wads of leaves or with soil. Major plugging peaks were recorded in March of both years of the study, midway through the wet season. At this time 49–59% of burrow entrances were sealed with a deep plug of soil, and many burrows remained plugged long enough for the crabs to molt. These data suggest that most red crabs molted annually at the study site.

The digestive tract contents of 85 Columbus crabs, Planes minutus, are presented. Crabs were collected from oceanic-stage loggerhead turtles, Carettta caretta, and inanimate flotsam near the Azores. The numbers of eggs carried by ovigerous crabs (n = 28) are also presented. Numbers of eggs between turtle crabs and flotsam crabs were similar. Dietary analysis yielded 11 food types from P. minutus. Crabs from turtles contained a higher diversity of food items than crabs from inanimate flotsam. The diet of P. minutus was composed primarily of neustonic invertebrates and algae—similar to prey items found from oceanic-stage loggerhead turtles in past studies. The types of food consumed by P. minutus suggest that crabs may obtain food by consuming other epibionts, by hunting neuston from their substrate, or by capturing food particles expelled by host turtles.

The larvae of the mangrove sesarmid crab Neosarmatium trispinosum Davie, 1994, were reared in the laboratory. Five zoeal stages and one megalopa are described in detail and illustrated. Morphologically, the zoea larvae of N. trispinosum are similar to those of other species of Neosarmatium in that they share most of the following characters: no lateral carapace spines; 1 5, 5, and 0 1 6 setae on the endopods of the maxillule, the maxilla, and the second maxilliped, respectively; uniform setal formula on the basis of the first (2,2,3,3) and the second (1,1,1,1) maxilliped. The differences between the zoeae and the megalopae of N. trispinosum and those of its congeners are discussed briefly.