The growth of Palaemon longirostris H. Milne Edwards, 1837, was studied in Mira River and estuary, SW Portugal, from October 1990 to September 1991. Size was measured as carapace length (CL), total body length (TL), and weight as wet weight (W). Females grew to larger size than males. Carapace length-frequency was used to determine the von Bertalanffy growth equation: L(t) = 11.68 (1 − e^{−0.62(t 0.49)}) for males and L(t) = 16.32 (1 − e^{−0.51(t 1.42)}) for females. The Munro's growth performance index (ϕ) was lower in males (1.927) than in females (2.133). Relationships between size measurements and weight were described with regression equations. Significant sex-specific variation was found in the slopes of the allometric relationships. Female carapace grew faster than total body length and weight, and the opposite was observed for males. In TL–W relationships, the weight increases faster than total body length in females and slower in males.

Allometric growth in three groups of American lobsters (Homarus americanus) found along the Northumberland and Atlantic coasts of Nova Scotia was compared. Three morphometric parameters were measured: (1) abdomen area, (2) carapace length, and (3) chelae length. Abdomen area and chelae length measurements were related to both carapace length and nominal length, which is (body mass)^1/3, while carapace length was related to nominal length. The scaling factors of abdomen area with carapace length for female lobsters were regionally different and were significantly greater than the isometric value of 2. Comparisons were made to published data for the scaling factors of abdomen area for the California spiny lobster (Panulirus interruptus) and differences were found. The data for Homarus were compared to previous measures of the scaling of fecundity for lobsters collected from similar regions of the province. The comparisons suggest that fecundity estimates used in current management strategies should be measured on a regional basis. Carapace length does not exhibit isometric growth when related to nominal length, and significant differences in relative growth exist between sexes. Chelae morphometrics were also regionally different for male lobsters and did not exhibit isometric growth.

The spotted spiny lobster, Panulirus guttatus, is a reclusive, reef-dwelling species and appears to be restricted to coral reef habitat for its entire benthic existence. Little is known about its population dynamics, and much of the data that are available is derived primarily from trap-caught individuals and may therefore be biased. We avoided this problem by diving at night on patch reefs in the Florida Keys (U.S.A.) to collect lobsters when they are most accessible and used mark-recapture methods to estimate their growth and size at maturity. Molt increment for lobsters greater than 50 mm CL was estimated to be 1.5 mm for females and 1.6 mm for males, while molt interval was 50.6 weeks for females and 50.0 weeks for males. Growth rate was calculated to be 0.02–0.37 mm CL/week depending on size and sex. On average, males grew faster than females, but the rate of growth decreased with increased size for both sexes. Female size at maturity was estimated at 32 mm CL, based on both the minimum size of egg-bearing females and the size at which 50% of the females produced eggs. We estimated size at maturity for males to be 36–37 mm CL, using the onset of allometric growth of the second walking leg as an indicator of male maturity. Panulirus guttatus is a diminutive species, and its size at maturity is small compared to other species of spiny lobster, although its growth rate is comparable to other species. These unusual life history characteristics may reflect selection for traits advantageous to life in small, architecturally complex habitat patches.

The relative growth of U. thayeri was studied for a subtropical mangrove population in the estuary of the Comprido and Escuro rivers, Ubatuba, São Paulo State, Brazil. The evaluation of the morphological sexual maturity of U. thayeri was performed using the allometric technique. Remarkable ontogenetic changes were observed in the allometric growth of the male major cheliped and the female abdomen, indicating that these structures are closely connected to the timing of sexual maturity. For males, the relative-growth analysis of cheliped propodus length rendered an estimate of 13.8 mm of carapace width for the size at onset of sexual maturity. A distinct growth pattern was observed for the abdomen of U. thayeri females. It has a wide puberty size range (from 10.7 to 16.8 mm of CW) compared to other brachyurans previously studied. Thus, the females' abdominal growth can be represented by three growth phases: immature, transitional, and mature. The major cheliped is the right one in 50% of males. The median length of the male major cheliped did not differ between right- and left-handed crabs.

The reproductive biology of female Dungeness crabs was studied with crab-pot and dive-transect sampling in five bays within or near Glacier Bay National Park and Preserve, southeastern Alaska, in April and September yearly from 1992 to 1998. A large percentage of nonovigerous, mature females was found in April, a time when females were expected to be brooding eggs that hatch in May and June. Our study examined differences between ovigerous and nonovigerous females collected in April and September samples to corroborate our previous laboratory study in which we found nonannual egg extrusion among Dungeness crabs. Seasonal differences in the catches of ovigerous and nonovigerous females, crab sizes, shell condition, and appendage injury were examined. Additionally, all crabs collected from two bays were tagged beginning in the fall of 1995; tagging was conducted twice annually. Our pot and dive data indicate that females, particularly larger ones, do not extrude eggs annually. Larger females have lower molting probabilities, which limits mating potential and increases reliance on stored sperm. The tagging study confirmed that at least some females do not extrude eggs in one year and then extrude eggs at a later time without molting, thus skipping at least one reproductive season. A reproductive cycle of Dungeness crabs in Alaska is introduced which includes earlier egg extrusion by larger females and nonannual egg extrusion.

Egg production and hatching success of four Acartia species from the Solent-Southampton Water estuarine system were determined under different temperature (5–20°C) and salinity (15–35 psu) laboratory regimes. Fecundity typically increased with increasing temperature for all species, and hatching success was suppressed at 5°C and 10°C in all species. With respect to salinity, egg production patterns were more irregular, but some species produced fewer eggs at the lowest salinity tested. At a 24 h incubation period, some differences in hatching success were obtained at the different salinities tested. Results indicate that temperature plays an important role in the population dynamics of the congeneric group Acartia within the system and that salinity changes may also influence the fecundity of the species.

Branchipus schaefferi and Streptocephalus torvicornis commonly co-occur in ephemeral ponds throughout the Mediterranean Region. We compared survivorship, growth, and reproduction. Our results show statistically significant differences in all three parameters under laboratory conditions at 25°C, reflecting different life history strategies between these species. Branchipus schaefferi grows quickly to 18 mm body length, producing roughly 1700 cysts during an average lifespan of 24 days, while S. torvicornis lives an average of 120 days (length 24 mm), laying 2400 cysts. This suggests that S. torvicornis is better adapted to deep longer-lived pools, whereas B. schaefferi may survive in small, more ephemeral pools as formed from spring melt water and autumn rains. While the lifespan is equal for both sexes in B. schaefferi, the males of S. torvicornis live 2.8 times longer than females (325 days versus 114) compelled into a long postreproductive period by lack of females in their environment.

Geothelphusa dehaani (White, 1874) is sympatric with G. exigua Suzuki and Tsuda, 1994, in Ohsumi Peninsula and with G. marmorata Suzuki and Okano, 2000, in Yakushima Island, southern Kyushu, Japan. Geothelphusa dehaani is widely distributed in Japan, whereas G. exigua and G. marmorata are endemic in riverine habitats at their respective locations. Visual and trapping surveys were conducted to examine the habitat preference and elucidate the factors maintaining sympatry among the three species. Results showed that G. exigua and G. marmorata are mainly aquatic, whereas G. dehaani is amphibious. Geothelphusa dehaani is more associated with land habitats under sympatry but equally extends in water and on land when singly constituting a population. All species exhibit varying degrees of nocturnalism, but G. marmorata is more active at night than either G. dehaani or G. exigua. Differences in habitats and activity patterns among the Geothelphusa species were attributed to their microenvironments and the effects of interspecific competition under sympatry.

Life cycle characteristics of the thalassinidean mud shrimp Upogebia major (de Haan), which is the deepest burrower among intertidal benthic animals in central Japan, were studied on a tidal flat along the northern coast of Tokyo Bay. Ovigerous females were observed from December to May. Females deposited eggs only once per breeding season, and eggs started hatching in March. Occurrence of the first zoea was observed in March and April, followed by benthic settlement in May. Growth over the first year was rapid, and females deposited their first eggs in the third breeding season, 31 months after their settlement. The data indicate that U. major has one of the longer immature periods among upogebiid shrimps. Adult shrimps live at least several years after maturation. Depth of the burrow increases with body length. The deep burrows of U. major provide refuge from predators and physical stress, allowing the shrimps to survive for a long time. The data from this study suggest that this species thus allocates more energy to rapid growth and adult survival than to quick reproduction.

Chthamalus stellatus and C. montagui are warm-water barnacles common on rocky shores in southwest England, Ireland, and southern Europe. They are partly sympatric, with overlapping vertical and horizontal distributions. It has been suggested that the differing horizontal distribution of the adults may be related to differences in the distribution of the larval stages. To this end, we have examined plankton samples taken during the summer breeding period at Plymouth, from inshore to 15 miles offshore. The samples also contained large numbers of other cirriped nauplii, notably Elminius modestus, Balanus perforatus, B. crenatus, and Verruca stroemia, from which the chthamalids had to be distinguished. The chthamalids can be separated from the other nauplii by use of characters that include a unilobed or trilobed labrum, the length of posterior processes and the shape and size of the cephalic shield, but the two species of Chthamalus are more difficult to distinguish. Scanning electron microscopy (S.E.M.) has allowed development of a key to the main barnacle nauplii occurring off the British Isles. This key, with accompanying SEM photographs, will enable enumeration of the two chthamalids and help answer the question whether there is a differential distribution of the larvae of these species.

An ovigerous crab of Heteropilumnus ciliatus (Stimpson) was collected in South Korean waters, and the larvae were reared in the laboratory. Three zoeal stages are described and illustrated in detail. Morphological characteristics of the first zoea of H. ciliatus differ from those described by Takeda and Miyake (1968). The first zoea of H. ciliatus appears to be similar to the first zoeas of Heteropanope glabra Stimpson and Pilumnopeus makiana (Rathbun), but they can be distinguished from each other by differences of the carapace spines. A provisional key is provided to aid the identification of the pilumnid zoeas in Korea and adjacent waters.

The presence of populations of the Afro-Asian cyclopoid copepod crustacean Mesocyclops thermocyclopoides Harada, 1931, in southeastern Mexico and in Central America is recorded. This species was recently redescribed in detail from Old World specimens. Because of the rarity of cosmopolitan forms in Mesocyclops, neotropical records of this species were suspected to be undescribed taxa of a widespread species complex. However, it was possible, through an upgraded morphological analysis and taxonomic comparison, to confirm the occurrence of M. thermocyclopoides in the neotropics. The American specimens are described in full. In the Americas, this species seems to be distributed in Mexico and Central America only. This is the third or fourth Asian or African species of the genus that has apparently been introduced into the New World by human agency. The others are M. pehpeiensis, M. ogunnus, and M. aspericornis.

The effect of latent inhibition on learning about cues related to increased predation risk was studied in a native crayfish, Orconectes virilis, and in an invasive species, Orconectes rusticus. Individuals of both species either were exposed or not exposed to the conditioned stimulus (potential “predator” odor = goldfish odor) prior to simultaneous exposure to conditioned (potential predator odor) and unconditioned (crushed conspecific = alarm odor) stimuli. Crayfish were then tested one day and one week later for inhibition of feeding responses following introduction of goldfish odor. Both species were clearly inhibited in their formation of an association between the goldfish odor and a predator risk stimulus after a training period during which they were exposed only to the goldfish odor. Thus, the effect of latent inhibition was demonstrated in both species. The implications for the learning of cues associated with predation risk are discussed.

This paper aims to elucidate the structure and characteristic mineralization of the gastric mill cuticle in the crayfish Procambarus clarkii (Girard) using light and transmission electron microscopy. Structure and mineralization of the lateral teeth of the gastric mill in the intermolt stage are documented. The lateral tooth is composed of two types: incisor-like teeth and molar-like teeth. The tooth structure is divided into three regions: “large-cusp region” is the protuberance region in the incisor-like teeth, “small-cusp region” is the protuberance region in the molar-like teeth, and “marginal region” is the surrounding region. The cuticle is divided into epicuticle, exocuticle, endocuticle, and membranous layer. The cuticle of the large-cusp region lacks epicuticle and endocuticle, while the cuticle of the small-cusp region lacks the epicuticle. The cuticle of the marginal region is composed of epicuticle, exocuticle, endocuticle, and membranous layer. Ultrastructurally, the exocuticle of the mill is composed of an electron-lucent matrix, pore canals, and electron-dense matrix surrounding the pore canals. The exocuticle in both cusp regions differs from that in the marginal region by the presence of a lamellar structure in the marginal region, which is composed of packed lamellae. During mineralization, needle-shaped crystals are deposited in the endocuticle. These crystals are found to consist of hydroxyapatite by electron diffraction and EDX. In conclusion, the structure of the gastric mill differs from that of the integumental cuticle, and the differences occur mainly in the exocuticle.

We examined Ohio and Mississippi River specimens of Orconectes that had been identified previously as O. placidus and collected new specimens or examined types of Orconectes luteus, O. placidus, O. forceps, O. medius, and O. rusticus from Illinois and other states. Our analyses revealed the presence of three species of Orconectes in the Ohio and Mississippi rivers, Orconectes luteus, O. placidus, and O. sp. (undescribed), based on chela morphometrics, gonopods, carpal spines, chela denticles, and life colors. All the Mississippi River records of O. placidus were O. luteus, and many of the Ohio River records of O. placidus were O. n. sp. Distinguishing characteristics for all three species, along with an addition to the dichotomous key to Illinois decapods, were included. The ranges of O. luteus, O. placidus, and O. n. sp. in Illinois were amended. Several problems were noted with the syntypes of O. placidus such as erroneous locality, misidentification, and mixing of specimens between localities. The ratio dactylus length/palm mesial margin length, which has been considered a distinguishing characteristic between O. forceps and O. placidus, was invalidated as a useful discriminator for these species, whereas presence or absence of a distomedian carpal spine was reliable. We consider Orconectes luteus and O. n. sp. native inhabitants of Illinois, and the latter species likely occurs in Kentucky portions of the Ohio River as well.

Procambarus (Austrocambarus) cavernicola, a new species of stygobitic crayfish known only from Gabriel Cave, Oaxaca, Mexico, is described. The new species is characterised by a body that lacks pigmentation, except for small purple spots on the eyes; with small setae on the tip of the eye; elongated chelipeds, with the surface of chela covered with small tufts of short setae; first pleopod of form I male with mesial process elongated and conical, triangular central projection, reduced cephalic process and cephalic shoulder forming convex border; annulus ventralis with preannular plate covered with short setae, postannuluar plate oval-shaped, with blunt tubercles. The new species is morphologically similar to other stygobite members of the subgenus Austrocambarus from the Oaxaca–Veracruz area, whose relationships are discussed. The distributions and levels of adaptation to the subterranean environment of 16 cave-inhabiting taxa of Procambarus in Mexico are reviewed.

One of the most important requirements for systematic and phylogenetic studies is the identification of gene regions with the appropriate level of variation for the question of interest. Molecular phylogenetic and systematic studies of freshwater crayfish have made use of DNA sequences mainly from ribosomal genes, especially the 16S rRNA gene region. Thus, little information is available on other potentially useful mitochondrial gene regions for systematic studies in these animals. In this study, we look at nucleotide variation and phylogenetic relations within and between four species of freshwater crayfish of the genus Cherax from the southwest of Western Australia using four fragments amplified from the 16S rRNA, 12S rRNA, Cytochrome Oxidase I (COI), and Cytochrome b (Cyt b) gene regions. Samples of Engaeus strictifrons, Euastacus bispinosus, and Geocharax falcata were also sequenced for comparative purposes. The size of the fragments varied from 358 bp to 600 bp. Across all samples, the four fragments showed significant phylogenetic signal and showed similar proportions of variable sites (28.81–37.33%). Average divergence within species for the mitochondrial gene regions varied from 1.18% to 4.91%, with the 16S rRNA being the least variable and Cyt b the most variable. Average divergence between species ranged 7.63–15.53%, with 16S rRNA being the least variable and COI the most variable. At the generic level, average divergence ranged 17.21–23.82%. Phylogenetic analyses of the 16S rRNA, 12S rRNA, and COI regions generated four clades consistent with the presence of four species previously identified on the basis of allozyme and morphological studies. The relationships among samples were largely congruent across the data set, although some relationships remained unresolved. Not all samples could be amplified using the Cyt b primers, and some of those that were showed quite anomalous relationships, suggesting that one or more Cyt b pseudogenes were being amplified.

The phylogeny of freshwater crayfish is assessed using a morphological analysis of fossil and extant taxa. Based on external morphological characters, primarily characters of the carapace and appendages, the crayfish comprise a monophyletic group (Astacida). The sister taxon to the crayfish is the Chilenophoberidae, a clade of extinct marine lobsters. Synapomorphies of the freshwater crayfish include a distinctive carapace groove pattern and mobility of the last thoracic segment. Within the Astacida, three smaller clades, considered to be family-level groups, are identified and redefined. All parastacid genera except Gramastacus comprise a monophyletic clade. Species in the Cambaridae are characterized by an apomorphous annulus ventralis in the female, and hooks on the ichiopodites on the third pereiopod in the male. Species in the Astacidae are characterized by randomly arranged tubercules on the medial portion of dactyl. The monophyly of the Astacoidea (Cambaridae plus Astacidae) is also supported. The familial affinity of Cambaroides is questioned, and this genus is tentatively reassigned from the Cambaridae to the Astacidae.

Phylogenetic reconstructions derived from analyses of DNA sequence variation in a segment of the mitochondrial ribosomal RNA (16S) gene revealed an extensive radiation of species within the genus Branchinella from Australia. Genetic differentiation was evident among all of the species analyzed, including two recently discovered species. There was limited agreement, however, concerning taxon affinities deduced from the 16S data and a previous morphological study. Members of the genus appear to have diversified rapidly, but analyses of other genes and broader taxon sampling are crucial to confirm this hypothesis. Disparities between levels of morphological and molecular change were noted between certain taxa. Whether the radiation of Australian Branchinella happened in situ or was the product of independent colonization events will require the analysis of branchinellids that occur outside Australia.

Based on a phylogenetic analysis of 104 genera and 156 species of corophiidean amphipods, we present a new phylogeny and higher-level classification for the suborder Corophiidea Leach, 1814. The phylogeny divides the corophiideans into two infraorders, the Corophiida and the Caprellida, based on a hypothesis of the evolution of different feeding strategies. Members of the Corophiida are derived from bottom-feeding detritivores, whereas members of the Caprellida are derived from ancestors that fed on material suspended in the water column. Within the Corophiida there are unspecialized clades such as the aoroids, whose members are mainly detrital feeders, as well as specialized forms feeding on living algae (family Ampithoidae) and on wood (superfamily Cheluroidea). In the Caprellida, members of the podocerid and caprellid clades often climb organisms such as hydroids in order to get their antennae as far up in the water column as possible to suspension-feed, whereas ischyrocerins build nests and then suspension-feed. Specialized forms include cyamids that attach to whales where they “feed on whale skin.” Barnard and Karaman (1984) divided the Corophiidea into two superfamilies (Corophiidea and Caprelloidea) within which were nine families. The classification presented here includes those two infraorders, with 11 superfamilies, 21 families, 13 subfamilies, and 5 tribes.

Management plans and stock assessment of exploited marine invertebrates should consider information on the genetic population structure of the species. In this context, the genetic diversity within and between populations of the commercially exploited hairy edible crab Cancer setosus was investigated using allozyme and AFLP (Amplified Fragment Length Polymorphism) markers, covering a range of approximately 2500 km along the Chilean coast. Genetic diversity estimates within populations, such as polymorphism and average expected heterozygosity, were low from two polymorphic allozyme loci, PGM-1 and EST-1 (P_0.99 = 8.7 %; H_E = 2.5 %) but much higher for 190 AFLP loci (P_0.99 = 52 %; H_E = 18.7 %). Nevertheless, differentiation among samples was statistically significant for allozymes (F_ST = 0.026; P < 0.001), but not for AFLPs (AMOVA ϕ_PT = 0.007; P = 0.118). Several possible causes of these differences are discussed in an evolutionary and oceanographic framework. AFLP also identified a sex-linked marker, present in 96 % of females but only 9 % of males. Relatively little is known about sex-determination in decapods, but these data suggest that in C. setosus, the mechanism is primarily genetic and that females may be the heterogametic sex.