Anomuran Crabs Research Articles

Population density estimates and conservation status of Aegla jacutinga Marçal & Teixeira, 2020 (Decapoda: Anomura: Aeglidae) from the type locality in Brazil

Abstract Anomuran crabs of the genus AeglaLeach, 1821 are endemic to temperate and subtropical regions of South America and are commonly found in streams and rivers, where they are generally restricted to healthy environments because they are sensitive to environmental changes. The genus presents worrying data regarding its conservation, like the many Brazilian freshwater species classified as being at some level of threat of extinction. We inventoried unexplored watersheds, estimated the population density of Aegla jacutinga Marçal & Teixeira, 2020 in its type locality, updated information on the distribution of the species, and assessed its conservation status using IUCN criteria.

Hidden diversity of Aegla (Decapoda, Anomura) in a priority area for conservation

AbstractAegla is a genus of freshwater anomuran crabs encompassing 94 described species occurring in meridional South America. Brazil harbours the greatest diversity of species, mainly in its southern region, which becomes a priority area for Aegla conservation due to high species richness and phylogenetic diversity, elevated endemism and threats to the Atlantic Forest. Here, we assessed Aegla richness and distribution in this priority area and tested the hypothesis of crypticism in the region's species. Sampling sites were distributed inside and in the surroundings of five protected areas, covering the major distribution range of several species described for southern Brazil. We applied three species delimitation methods to COI mitochondrial gene data, coupled with phylogenetic and morphological analyses. By integrating species delimitation based on the COI data and traditional taxonomy, we uncovered a high proportion of hidden diversity among Aegla in our study area and identified ten known species besides impressive 17 new putative species. Of these, eight are possible new taxonomic units that do not conform to any known species, and nine are divided into three cryptic groups: Aegla jarai complex, Aegla franciscana complex and Aegla camargoi complex. Most of these species have a narrow spatial distribution, making them highly vulnerable to habitat degradation. Despite the real richness of the genus still being largely unknown, the high diversity revealed here makes our study area the richest known region regarding the number of Aegla species within its distribution, making this area even more worthy for conservation efforts.

In vitro immune analysis of serum from the hemolymph of the anomuran crab Albunea symmysta (Linnaeus, 1758) displayed diversified reactions

The present investigation aims to substantiate that serum from the hemolymph of anomuran crab Albunea symmysta encompasses multiple immunological reactions in in vitro condition. The serum highly agglutinated human O erythrocytes in the presence of Ba2+. Distinct and unique sugar binding capacity of serum towards laminarin, N-acetyl sugars and higher binding specificity towards a glycoprotein, fetuin was inferred. In vitro enhancement of melanin synthesis due to enhanced oxidation of 3, 4-dihydroxy-dl-phenylalanine (dl-DOPA) by preincubation of nonself molecules with serum phenoloxidase (PO) was documented. Similarly, dl-DOPA oxidation by serum PO was reduced when preincubated with chemical inhibitors and copper chelators. Further, the crab serum lysed the vertebrate erythrocytes with maximum hemolysis against chicken and it unveiled dependency on divalent cation, serum concentration, ionic strength, pH, temperature and time interval. Occurrence of maximum hemolysis at a concentration of 30 µl, pH 8.0, temperature 37 °C and time interval of 60 min in the presence of Ba2+ were documented. Interestingly, serum hemolysis was reduced by different osmoprotectants suggesting a colloid-osmotic mechanism involving in hemolysis. It was observed that A. symmysta serum had antimicrobial activity against Gram-positive Staphylococcus aureus and fungal pathogen Candida albicans. The serum showed higher glycan content, potent lysozyme and free radical scavenging activity suggesting the existence of potential immune molecules of therapeutic use. These results clearly demonstrated the diversified immunogenicity of A. symmysta serum confirming a highly conserved non-specific immunity of crustaceans

Null models to explain highly diverse community of intertidal decapods on a temperate rocky coast in Antofagasta, northern Chile (23º27ʹS)

Abstract The decapod fauna on intertidal shores in northern Chile is characterized by its relatively high diversity and abundance due to the presence of continuous upwelling by the Humboldt Current, which results in a high productivity. The decapod fauna on intertidal rocky shores is characterized by coexisting species that inhabits in natural shelters such as cracks and eroded rocks, as well as among macroalgae. We aimed to monitor the brachyuran and anomuran (porcellanid) crabs in three intertidal sites during two periods of time in September-December 2019 in the Antofagasta region, one site without human intervention and two sites in the city of Antofagasta, for which we applied null models in ecology. We assumed that the communities are random, a viewpoint that is more robust because it reduces the risk of error type I. The results of the application of null models on the co-occurrence species revealed that species associations are mainly structured for all sites, whereas the niche-sharing null model revealed that the reported species did not share ecological niches and in consequence there is not interspecific competition. The results would probably indicate that the species of intertidal decapods have a micro-specific ecological-niche differentiation, which would explain the existence of structured pattern in species associations. The results were compared with information for other sites along the continental Chilean coast.

Variation and taphonomic implications of composition in modern and fossil malacostracan cuticles (Decapoda: Malacostraca)

Abstract The crustacean fossil record is dominated by mineralized forms. These fossils, in turn, are mainly decapod chelae or parts of chelae. Studies of the composition of modern crustacean cuticles have likewise been dominated by decapods. We summarize major element chemical analyses (Ca, Mg, Na, P) using SEM-EDS of modern crustacean exoskeletons from Bermuda, Georgia (USA), and Lake Tanganyika (Burundi). Although most specimens were brachyuran and anomuran crabs, material also included examples of stomatopods, isopods, caridean shrimps, and achelatans. Transects were made of sections of the carapace, palm of the propodus, and tips of either the dactyl or propodus. Multiple transects were made of the Bermudan land crab Gecarcinus lateralis. Additional studies were made of brachyuran fossil crabs from Texas and South Dakota and of brachyuran crabs having undergone ten months of burial in marine sediments. Overall, the tips of the chela were the thickest and most heavily mineralized regions and had the lowest phosphorus content. In nearly all cases, they also had the lowest ratios of Mg to Ca. One notable exception was Gecarcinus, where the denticles had elevated Mg:Ca values. Anomura and Brachyura had markedly different composition from Stomatopoda and possibly Isopoda, suggestive of independent evolutionary origins of biomineralization within the Crustacea. There were also significant differences in composition between brachyuran crabs from Georgia and Bermuda, perhaps due to differences in water temperature. The fossil crustaceans had much more phosphate in their cuticles, likely as a result of diagenetic processes. Composition should be a first order control on the fossil record of crustaceans. Future studies need to expand the taxonomic and geographic ranges of material examined, determine whether there are environmental controls on composition, and explore the relevant diagenetic processes.

β-Carotene Analysis and Histological Investigation on Different Egg Stages of Anomuran Crab, Emerita Asiatica (H. Milne Edwards, 1837)

Histological investigation and β-carotene analysis of different egg stages of anomuran crab, Emerita asiatica was studied. This investigation characterized the morphological and histological features of the ovaries; eggs and also resulted in the identification of the following structures such as Previtellogenic Oocyte, Vitellogenic Oocytes, Atretic Oocyte, matured Oocyte and its associated structures which are quiet common structures that are found in almost every Sand Crab. This study can be further used in studying the reproductive biology of this Sand Crab (Emerita asiatica). It can also be used in determining the structural and morphological changes that can happen in gonads due to the action of various microorganisms such as bacteria, viruses and fungi by artificial infections. The observation described in this study will serve as a reference for future research aimed at studies based on environmental factors, temperature, climatic conditions, and feeding that might have an effect on this species. The conversion of β-carotene into vitamin A (retinol), for clear eyesight and healthy eyes, a robust immune system, and healthy skin and mucous membranes, we require vitamin A. Large amounts of vitamin A can be hazardous, but our bodies only make as much of the vitamin from β-carotene as is required. The sand crab serves as a different source of β-carotene than vitamin A, even though E. asiatica is not widely used. Though E. asiatica is not a commercially viable crab, it plays a vital role in the environment to maintain a stable marine ecosystem. Several steps and preventive measures should be taken to conserve these members of the marine food chain to have a stable ecosystem and also to protect this species from extinction. Further, this study can potentially benefit as baseline information for the future research on the species.

Acute Toxicity of Chlorpyrifos on Histological Alterations in the Anomuran Crab, Emerita asiatica (H. Milne Edwards, 1837)

Acute toxicity of Chlorpyrifos on histological alterations in the different organs like gills, hepatopancreas and ovary of anomuran crab, Emerita asiatica was studied. Though Emerita asiatica is not a commercially viable crab, but it plays a vital role in the environment to maintain a stable marine ecosystem. Several steps and precautions measures should be taken to conserve these members of the marine food chain to have a stable ecosystem and also to protect this species from extinction. Thus, it can be concluded that the use of Chlorpyrifos which has been legally banned in India is justified. It has been proved by several workers and has been conformed in present investigation that use of this Chlorpyrifos causes serious damage to the vital organ of sand crabs gill, hepatopancreas and ovary. The application of Chlorpyrifos could be reduced in the agricultural field to nearby coastal regions.

Acute Toxicity of Monocrotophos on Histological Alterations in the Anomuran Crab, Emerita asiatica (H. Milne Edwards, 1837)

This study characterized the acute toxicity of Monocrotophos on histological alterations in the different organs like gills, Hepatopancreas and ovary of Anomuran Crab, Emerita asiatica. Though Emerita asiatica is not a commercially viable crab, but it plays a vital role in the coastal environment to maintain a stable marine ecosystem. Several steps and precautions measures should be taken to consume these members of the marine food chain to have aunwavering ecosystem and also to protect this species from extinction. Thus, it can be concluded that the use of Monocrotophos which has been legally banned in India is justified. It has been proved by several workers and has been conformed in present investigation that use of this organophosphate causes serious damage to the vital organ of sand crabs gill, hepatopancreas and ovary. The utilization of Monocrotophos should be minimized in the agricultural field area near to the coastal ecosystem.

Mitochondrial genomes of the land hermit crab Coenobita clypeatus (Anomura: Paguroidea) and the mole crab Emerita talpoida (Anomura: Hippoidea) with insights into phylogenetic relationships in the Anomura (Crustacea: Decapoda)

The infraorder Anomura is a species-rich clade of decapod crustaceans recognized by its remarkable disparity in terms of morphology, anatomy, ecology, physiology, and behavior. This study assembled and characterized the complete mitochondrial genomes of two anomuran species, the hermit crab Coenobita clypeatus and the mole crab Emerita talpoida. The AT-rich mitochondrial genomes of C. clypeatus and E. talpoida are 16,469 bp and 15,810 bp long, respectively, and are composed of 13 protein-coding genes (PCGs), two ribosomal RNA genes, and 22 transfer RNA genes. A 1,390 bp and 553 bp long intergenic space is assumed to be the D-loop in C. clypeatus and E. talpoida, respectively. Mitochondrial synteny in C. clypeatus is identical to that reported in other congeneric hermit crabs while synteny in E. talpoida is identical to that described for the confamilial mole crab Stemonopa insignis. No major differences occur between the studied species and their respective congeneric / cofamilial species in terms of nucleotide composition and codon usage profiles of PCGs. Selective pressure analysis in PCGs, rarely conducted in anomuran crabs, indicate that all these mitochondrial PCGs experience purifying selection and that this purifying selection is stronger in some (i.e., cox family genes and cob) compared to other PCGs (e.g., atp8). Most of the tRNA genes exhibited a typical ‘cloverleaf’ secondary structure with few exceptions in the two studied species. In C. clypeatus, tRNA-Ser1 lacks the thymine pseudouracil cytosine (TΨC) loop while tRNA-Phe and tRNA-Tyr each exhibit a deletion of the dihydroxyuridine (DHU) loop but not the arm. In turn, in E. talpoida, tRNA-Phe and tRNA-Arg exhibit a deletion of the DHU loop but not the arm while tRNA-Ser1 lacks the TΨC arm. A phylogenomic analysis based on translated PCGs confirms the monophyly of the infraorder Anomura and retrieves most/all relationships at the superfamily and family level previously reported for anomurans. The analysis supports the monophyletic status of the families Albuneidae, Lithodidae, Coenobitidae, and Porcellanidae. In turn, the superfamily Paguroidea, and the families Paguridae and Diogenidae are polyphyletic.

An annotated checklist of anomuran species (Crustacea: Decapoda) of India

An annotated checklist of the anomuran crustaceans recorded from Indian waters is compiled from available published literature. A total of 231 species belonging to 58 genera, 15 families and five superfamilies are listed. The highest number of species was seen in the Andaman and Nicobar Islands Ecoregion (114 species, 37 genera, 14 families), followed by the South India Ecoregion (111 species, 41 genera, 14 families), West India Ecoregion (93 species, 36 genera, 14 families), Eastern India Ecoregion (76 species, 29 genera, 12 families), Maldives Ecoregion (34 species, 15 genera, 10 families) and Northern Bay of Bengal Ecoregion (22 species, nine genera, five families). Notes on the questionable identifications and records of some anomuran crabs are also provided.

Evolvability in the Cephalothoracic Structural Complexity of Aegla araucaniensis (Crustacea: Decapoda) Determined by a Developmental System with Low Covariational Constraint.

Simple SummaryThe origin of complex morphological structures is explained mainly by direct pathways fusing adjacent modules, while the independent effect of parallel pathways acting on different areas of a morphogenetic field is less well-known. The palimpsest model that explains the cephalothoracic structural complexity of decapod crustaceans is composed of two hox-regulatory parallel pathways that tagmatize the anterior metameres early, followed by a direct pathway that fuses the tagmata forming the developmental modules. The cephalothoracic geometry of Aegla araucaniensis shows a marked sexual dimorphism; its adaptive causes also promote dimorphic variations in the evolvability of developmental modularity. We found areas of instability in the variance of the asymmetry in both developmental modules. The direct pathway presents intermediate levels of canalization in the covariation of the developmental modules, although significantly higher in males. This low restrictive potential promotes expressions of gonadic modularity in females and agonistic modularity in males, which differ significantly from developmental modularity. The cephalothoracic palimpsest model of decapods allows studying modularity in an explicit evo–devo context.The integration of complex structures is proportional to the intensity of the structural fusion; its consequences are better known than the covariational effects under less restrictive mechanisms. The synthesis of a palimpsest model based on two early parallel pathways and a later direct pathway explains the cephalothoracic complexity of decapod crustaceans. Using this model, we tested the evolvability of the developmental modularity in Aegla araucaniensis, an anomuran crab with an evident adaptive sexual dimorphism. The asymmetric patterns found on the landmark configurations suggest independent perturbations of the parallel pathways in each module and a stable asymmetry variance near the fusion by canalization of the direct pathway, which was more intense in males. The greater covariational flexibility imposed by the parallel pathways promotes the expression of gonadic modularity that favors the reproductive output in females and agonistic modularity that contributes to mating success in males. Under these divergent expressions of evolvability, the smaller difference between developmental modularity and agonistic modularity in males suggests higher levels of canalization due to a relatively more intense structural fusion. We conclude that: (1) the cephalothorax of A. araucaniensis is an evolvable structure, where parallel pathways promote sexual disruptions in the expressions of functional modularity, which are more restricted in males, and (2) the cephalothoracic palimpsest of decapods has empirical advantages in studying the developmental causes of evolution of complex structures.

Heterochely and cheliped dimorphism in the porcellanid crab Petrolisthes japonicus (De Haan, 1849) (Decapoda: Porcellanidae)

Cheliped dimorphism is common in decapod crustaceans, and many decapods have a pair of different-sized chelipeds, i.e., one side being larger (major) than the other (minor), a phenomenon known as heterochely. Anomuran crabs from the family Porcellanidae exhibit a true crab-like body shape, with relatively large chelipeds for their body size, and they show a sexual size dimorphism of chelipeds (i.e., males with larger chelipeds). However, very little is known about heterochely in porcellanid crabs. Therefore, we aim to elucidate heterochely and cheliped dimorphism in the porcellanid crab Petrolisthes japonicus (De Haan, 1849). We examined the laterality of the chelipeds and performed allometric growth analyses of the cheliped dimensions. Heterochely was observed in most of the specimens, and major chelipeds occurred randomly on either the right or left sides of the body, regardless of the crab size. Major and minor cheliped size of males surpassed female cheliped size, and males increased the growth of both major and minor chelipeds to the same degree during the breeding season, thereby inducing the distinct intersexual size dimorphism of the cheliped. This is probably attributable to sexual selection (i.e., male-male competition). Intersexual dimorphism as an energy allocation strategy was also evident with females allocating their energy evenly to both major and minor cheliped growth without changing the chela shape; regardless of the body size, whereas males were investing more energy in major cheliped growth, resulting in wider chelae with increasing body size. Consequently, the major cheliped may have a greater role in male-male competition in P. japonicus.

Sentience in decapod crustaceans: A general framework and review of the evidence

We outline a framework for evaluating scientific evidence of sentience, focusing on pain experience. It includes eight neural and cognitive-behavioural criteria, with confidence levels for each criterion reflecting the reliability and quality of the evidence. We outline the rationale for each criterion and apply our framework to a controversial sentience candidate: decapod crustaceans. We have either high or very high confidence that true crabs (infraorder Brachyura) satisfy five criteria, amounting to strong evidence of sentience. Moreover, we have high confidence that both anomuran crabs (infraorder Anomura) and astacid lobsters/crayfish (infraorder Astacidea) meet three criteria—substantial evidence of sentience. The case is, as yet, weaker for other infraorders, such as penaeid shrimps, highlighting important research gaps. Having demonstrated our framework’s application to decapod crustaceans, we hope that future research will apply it to other taxa.

Spatial partitioning between juveniles and adults of the freshwater anomuran crab Aegla parana (Crustacea Aeglidae) from southern Brazil

Spatial partitioning between juveniles and adults of the freshwater anomuran crab Aegla parana (Crustacea Aeglidae) from southern Brazil

Porcellanid crab Pachycheles stevensii parasitized by rhizocephalans Lernaeodiscus spp.: population biology in the northwestern Sea of Japan.

We examined the population and reproductive characteristics of the anomuran crab Pachycheles stevensii Stimpson, 1858 (Decapoda: Porcellanidae) heavily infested by 2 rhizocephalans of the genus Lernaeodiscus in the northern part of the species range (Peter the Great Bay, Sea of Japan) in 2020-2021. The prevalence of infestation reached 32.3%, and L. rybakovi proved to be much more numerous than L. kasyanovi. The sex structure of the P. stevensii population was represented by males (38.8%), females (50.6%), and modified specimens (10.6%), which were extremely feminized males. The latter had a broadened abdomen, smaller chelae, shortened gonopod, and 3 additional pairs of female-type pleopods. Thus, the initial sex ratio in the P. stevensii population approximated the expected 1:1, as in most porcellanid crabs. No significant modifications of the secondary sex characters of the female hosts were observed. The size structures of males and females did not significantly differ. P. stevensii produced 1 clutch yr-1. Oviposition and incubation lasted from summer to early fall; recruitment was noted in the fall. There was a correlation between the reproductive cycles of the host and parasites: rhizocephalans with mature externae were found from June-October. A large number of ovigerous female P. stevensii simultaneously carried parasitic externae of L. rybakovi; fecundity was considerably higher in non-infested females.

Distribution pattern in Aegla uruguayana Schmitt, 1942 (Decapoda: Anomura: Aeglidae): temporal and spatial approach

Abstract The presence, density, and distribution pattern of a species in a particular space and time result from evolutionary and ecological processes. We evaluated the density and spatial distribution pattern of the freshwater anomuran crab, Aegla uruguayanaSchmitt, 1942, in relation to temporal and spatial scales. The temporal scale followed a seasonal analysis, and the space scale was evaluated from the study of three streams located in different provinces of Argentina. Specimens were collected in four sampling campaigns during spring, summer, autumn, and winter in three temperate freshwater environments of the La Plata Basin, Argentina, using 1 m2 sampling units. The density varied according to the studied populations and was not by seasonality. The distribution pattern was not influenced by the evaluated scales. The A. uruguayana populations presented a clumped pattern showing a negative binomial distribution. A possible cause of such a pattern is the strong environmental heterogeneity of the three studied sites. The species presented gregarious behavior that could be associated with the spatial arrangement of the shelters available in the particular habitats as well as ecological strategies for optimal and efficient use of resources in these topographies. Our study is the first on the dynamics of the distribution in terms of temporal and spatial scopes of a species of AeglaLeach, 1820, an endemic freshwater anomuran.

Aegla buenoi n. sp. (Decapoda: Anomura): first record of aeglid crab from Cinzas River basin, Brazil.

A new species of freshwater anomuran crab, Aegla buenoi n. sp., is described. The new taxon was collected from two streams within the Cinzas River basin, Paran state, Brazil. We used morphological and molecular data (COI mtDNA) to distinguish the new species from its congeners. Aegla buenoi n. sp. is differentiated by morphological diagnostic features of the cephalothorax, chelipeds, second abdominal epimeron, and uropods. Molecular results confirm the separation of A. buenoi n. sp. from closely related species (A. castro Schmitt, 1942, A. lata Bond-Buckup Buckup, 1994, and A. jacutinga Marl Teixeira, 2020). Hence, our study increases the known diversity of aeglids and reports the first species of Aegla from the Cinzas River basin.

Serum phenoloxidase activity in the hemolymph of the anomuran crab Albunea symmysta (Linnaeus, 1758) (Decapoda: Anomura: Albuneidae)

Abstract We characterized the optimal conditions for measuring serum phenoloxidase activity and its functional activity and susceptibility to an inhibitor and various activators in an anomuran crab, Albunea symmysta (Linnaeus, 1758). The substrate affinity of the phenoloxidase (PO) enzyme was determined using different phenolic substrates in which only diphenols were found to be oxidized. The enzyme was characterized as a catecholoxidase-type of PO and 3,4-dihydroxy-DL-phenylalanine (DL-Dopa), the enzyme showing the highest substrate affinity to the serum. The optimal enzyme activity was observed at 5 mM DL-Dopa in 10 mM Tris-HCl buffer at a pH of 7.5 at 25 °C for 10 min, and absorbance at 470 nm. Serum-PO activity was inhibited by 7 mM phenylthiourea (PTU), and activated by activators such as trypsin, chymotrypsin, pronase-E, and detergent-like sodium dodecyl sulfate (SDS). We also identified the chemicals causing in vitro inhibition or activation of the enzyme as a serum of the crab having a potent PO activity.

Gonadal development, reproductive investment and fecundity of Aegla castro Schimitt, 1942 (Crustacea, Anomura)

ABSTRACT Aegla castro, is an endemic anomuran crab from Brazil found in headwater streams of the Atlantic Forest on the Paranapanema River basin. This study aims to evaluate the gonadal maturity of A. castro based on macroscopic and microscopic analyses. Crabs were collected in Mauá da Serra (23º57’ S; 51º06ʹ W), Paraná, Brazil in the winter and spring of 2015, and summer, autumn, and spring of 2016. Individuals had their gonads analysed and categorized into stages of development. Stage1, ovaries are macroscopically undetectable through abdominal transparency, while ovaries of stages 2 and 3 could be detected through abdominal transparency and have characteristic colour and length in relation to the abdominal somites. Ovaries have pre-vitellogenic and vitellogenic oocytes in all stages of development, with germ cells and structural epithelium characteristic of these gonadal maturation phases. Spermatogenesis in males begins in spring, with the production of spermatozoa in autumn and spermiation in winter. Aegla castro has seasonal reproduction. The macroscopic stages of gonadal development correspond to the histological gonadal maturation, indicating that the macroscopic observation of the gonads of live animals is feasible in studies of the reproductive cycle of aeglids.

Seasonal Changes in the Sexual Size Dimorphisms of the Chelipeds and Pleons of the Porcellanid Crab Petrolisthes japonicus.

Decapod crustaceans develop secondary sexual structures, such as large chelipeds for weaponry and/or display in males and a wider pleon for incubating eggs in females. These structures should be costly to produce and maintain; hence, the crustacean reproductive strategy might have adapted to conserve energy for developing secondary sexual characteristics during the reproductive season. However, little is known about seasonal changes in the sexual size dimorphisms of the chelipeds and pleons of decapod crustaceans. Anomuran crabs from the family Porcellanidae exhibit a true crab-like body shape, with relatively large chelipeds for their body size and a well-developed pleon. They also show sexual size dimorphism (i.e., males with larger chelipeds and females with wider pleons); therefore, it was expected that seasonal changes in the sexual size dimorphisms of these organs would occur in porcellanid crabs. We tested this expectation using Petrolisthes japonicus, which is common on the intertidal cobble and boulder shores of the temperate and tropical regions of Japan. We employed allometric growth analyses of the cheliped and pleon dimensions of P. japonicus females and males collected over a year. Our analyses supported our expectation regarding the seasonal changes in the sexual size dimorphisms of the chelipeds and pleons in P. japonicus. Intersexual size dimorphism of the chelipeds and pleons was evident during the breeding season: females allocated more energy to pleon growth, while reducing cheliped growth, and investment in the pleon increased with increasing female body size, whereas males invested their energy in cheliped growth, and the investment in chelipeds increased with increasing male body size. During the nonbreeding season, females and males conserved energy by reducing the size of pleons and chelipeds relative to their respective body sizes. Our results highlighted the sex-specific and season-dependent resource allocation and reproductive strategies of porcellanid crabs.