Land Crab Research Articles

Rapid evolution to terrestrial life in Jamaican crabs

Crabs of the family Grapsidae are abundant organisms in most intertidal communities. However, relatively few species live in complete independence of the sea1. Of those species that do, Jamaica's nine endemic species of land crabs are unique in their exceptional adaptations to terrestrial life, which include the only active brood-care for larvae and juveniles known in crabs2,3,4,5,6. These adaptations, and the morphological similarity to a group of southeast Asian land-dwelling crabs, have raised the question of the number and age of land invasions of the Jamaican species. Here we present molecular evidence that Jamaican land crabs represent a single adaptive radiation from a marine ancestor that invaded terrestrial habitats only 4 million years (Myr) ago. A Late-Tertiary origin has also been found for lizards and frogs of Jamaica7,8,9 and probably reflects the Mid-Tertiary inundation of that island10.

Land-loving crabs

The nine species of land crab in Jamaica are adapted extraordinarily well to terrestrial life. They vary considerably, however, according to their particular habitat. A phylogenetic analysis of sequences from two mitochondrial genes now shows that all the species had a common marine ancestor. Moreover, in evolutionary terms, it seems that the current diversity has arisen very quickly —that is, within the past four million years or so.

Digestive strategies in two species of leaf-eating land crabs (Brachyura: Gecarcinidae) in a rain forest.

Two species of herbivorous land crabs from Christmas Island, Cardisoma hirtipes and Gecarcoidea natalis, overlap in both diet and distribution. This study compared the dietary preferences and digestive capabilities of these two species on a diet of leaf litter to establish the digestive strategies each adopts and the likely degree of competition for food. C. hirtipes preferred green to yellow or brown leaves of Ficus macrophylla in short-term food-choice experiments. Brown leaves were least favoured. G. natalis showed no preference for the different leaf types and in the field ate chiefly brown and decomposing leaf litter. When fed green leaves, C. hirtipes had a low food intake (4.5+/-0.36 g kg-1 d-1) and a short retention time for food, and the readily digestible components of the diet constituted greater than 84% of the dry matter assimilated. When fed brown leaves, the intake was increased 3.3 times, but retention time remained short, and assimilation coefficients for all nutrients were low. The readily digestible fraction of the diet made the chief contribution to dry matter assimilation (69%), and hemicellulose (19%) and cellulose (21%) were also significantly used. This pattern of food intake and assimilation contrasts with that for G. natalis, which had a low intake of brown leaves and a longer retention time associated with higher nutrient assimilation, particularly of complex polysaccharides. It is suggested that through their feeding preferences and habits, these two sympatric species use opposite ends of the leaf litter quality spectrum on Christmas Island.

The freshwater crab fauna (Crustacea: Brachyura) of the Philippines. V. On a new genus and species of potamid from Palawan island, Philippines

A new genus and new species of terrestrial potamid crab ( Carpomon pomulum) is described from the island of Palawan in the Philippines. This new genus can easily be distinguished from all other Philippine potamids in its smooth and inflated carapace, no trace of an epibranchial tooth, extremely low postorbital cristae, and stout and twisted male first gonopod.

Terrapotamon Palian Sp. Nov., a Second Member of the Terrestrial Crab Genus Terrapotamon (Decapoda, Brachyura, Potamidae) From Southern Thailand

A second species of the previously monotypic terrestrial potamid crab genus, Terrapotamon Ng, 1986, is described from southern Thailand. The new species, T. palian, can be distinguished from T. abbotti (Rathbun, 1898) by characters in the carapace, exorbital tooth, postorbital cristae, chelipeds, ambulatory legs and male first pleopods, as well as in the form of the frontal, postorbital and suborbital regions.

Integration of physiological responses of crustaceans to environmental challenge

Brachyuran crustaceans are useful models for physiological studies because of their intermediate size and since they occupy a spectrum of habitats requiring widely varied behaviour. In this paper we examine the physiological responses to environmental fluctuations, extremes of habitat and consequent behaviours, with special emphasis on the adoption of air-breathing. It is established that metabolic end products such as lactate, intermediates including urate, and monoamine and peptide neurohormones can have important regulatory roles. These include effects on ventilation and heart function, blood perfusion, respiratory gas transport, as well as water and salt homeostasis providing an integrated suite of control mechanisms to regulate responses to environmental or behaviourally induced stress. A separate body of work has long suggested that the regulation of energy metabolism and provision of metabolic fuel for glycolysis is influenced by similar effectors. Most recently, metabolic end-products have been implicated as effectors of behaviour and thereby metabolic state. Thus, there is strong, emerging evidence for integration of physiological control mechanisms at the organismal level. We present new information, both mechanistic and from eco-physiological laboratory simulations, and from field studies of terrestrial crabs, that strengthens and extends the scope of this integration. Branchial chamber ventilation, cardiovascular function, relative perfusion of gills v. lungs, gas transport in the blood, the mobilisation of energy reserves, ion transport and water balance are all apparently influenced by similar messengers which coordinate and optimise these functions to meet specific requirements.

Characterization of vitellogenin and vitellin from land crabPotamon potamios: Identification of a precursor polypeptide in the molecule

A female-specific protein, vitellogenin (Vg), and its corresponding egg vitellin (Vn) were identified in the land crab Potamon potamios. Electrophoretic analysis of the hemolymph protein during the annual reproduction cycle revealed that the processing of vitellogenesis did not occur in males or in females of a previtellogenic stage. The analysis of ovarian and egg extracts revealed the presence of Vn, which was identical to Vg. Both Vg and Vn were present in three different aggregational states that represented monomeric, dimeric, and trimeric species of the proteins. In both proteins, the predominant form was the dimeric, which had a molecular mass of 551 kDa for Vg and 510 kDa for Vn. Under denaturing conditions, each of the individual Vg and Vn aggregates released three polypeptides with molecular masses of 115, 105, and 85 kDa. In spite of the difference in terms of native molecular mass, the Vg and Vn were similar in their lipid, carotenoid, and carbohydrate composition. However, Vg of some animals contained a fourth polypeptide with a molecular mass of 181 kDa. This polypeptide and the three other Vg and Vn polypeptides were immunoreactive against anti-Vg prepared from the 85 kDa Vg polypeptide. Furthermore, proteolytic cleavage experiments confirmed that the 115 and 105 kDa Vg polypeptides were derived from the 181 kDa polypeptide. We conclude that the presence of the 181 kDa polypeptide in the Vg molecule resulted in the higher molecular mass of Vg.

Control of Seedling Recruitment by Land Crabs in Rain Forest on a Remote Oceanic Island

We tested the hypothesis that an omnivorous land crab determines the dynamics of seedling recruitment in rain forest on Christmas Island, Indian Ocean. The red crab (Gecarcoidea natalis) occurs at densities of ∼1 crab/m2 and consumes seeds, seedlings, and leaf litter. A crab-exclusion experiment below closed canopy and in light gaps showed that red crabs markedly reduced seedling recruitment. Overall, seedling emergence was 29-fold and 21-fold greater on the exclusion plots in the understory and in gaps, respectively. In control plots, mean seedling densities never exceeded 15 seedlings/25 m2 in the understory and 3 seedlings/25 m2 in gaps. Species richness of seedlings was significantly higher in the absence of crabs, averaging >10 and 12 species per plot in the understory and gaps, respectively. On control plots, mean species richness was less than one species per plot. Two-dimensional ordination (using nonmetric multidimensional scaling) showed that red crabs had a large impact on relative species abundances. Analyses of similarity confirmed that significant differences existed between both treatments and habitats. Seed removal and seedling transplant experiments suggested that most rain forest species are rapidly eaten by red crabs. Seedlings of many of these vulnerable species (e.g., Maclura cochinchinensis, Planchonella nitida, Schefflera elliptica) were abundant on exclusion plots. However, they were rare on control plots, and none persisted for >2 mo. Persistent seedlings were limited to two species (Inocarpus fagifer and Tristiropsis acutangula), both of which were resistant as seeds and seedlings to crab predation. Although red crabs are the major biotic determinants of seedling recruitment, this impact was not reflected in the overhead canopy. Some tree species unable to recruit in the presence of crabs were common as adults. Shifting mosaics in crab densities over space and time may offer the best explanation for recruitment of vulnerable species. Our results show that a dominant consumer has large effects on plant community structure on a remote oceanic island, consistent with the viewpoint that strong control by a single species is more likely in simple communities.

CONTROL OF SEEDLING RECRUITMENT BY LAND CRABS IN RAIN FOREST ON A REMOTE OCEANIC ISLAND

We tested the hypothesis that an omnivorous land crab determines the dynamics of seedling recruitment in rain forest on Christmas Island, Indian Ocean. The red crab (Gecarcoidea natalis) occurs at densities of ∼1 crab/m2 and consumes seeds, seedlings, and leaf litter. A crab-exclusion experiment below closed canopy and in light gaps showed that red crabs markedly reduced seedling recruitment. Overall, seedling emergence was 29-fold and 21-fold greater on the exclusion plots in the understory and in gaps, respectively. In control plots, mean seedling densities never exceeded 15 seedlings/25 m2 in the understory and 3 seedlings/25 m2 in gaps. Species richness of seedlings was significantly higher in the absence of crabs, averaging >10 and 12 species per plot in the understory and gaps, respectively. On control plots, mean species richness was less than one species per plot. Two-dimensional ordination (using nonmetric multidimensional scaling) showed that red crabs had a large impact on relative species abundances. Analyses of similarity confirmed that significant differences existed between both treatments and habitats. Seed removal and seedling transplant experiments suggested that most rain forest species are rapidly eaten by red crabs. Seedlings of many of these vulnerable species (e.g., Maclura cochinchinensis, Planchonella nitida, Schefflera elliptica) were abundant on exclusion plots. However, they were rare on control plots, and none persisted for >2 mo. Persistent seedlings were limited to two species (Inocarpus fagifer and Tristiropsis acutangula), both of which were resistant as seeds and seedlings to crab predation. Although red crabs are the major biotic determinants of seedling recruitment, this impact was not reflected in the overhead canopy. Some tree species unable to recruit in the presence of crabs were common as adults. Shifting mosaics in crab densities over space and time may offer the best explanation for recruitment of vulnerable species. Our results show that a dominant consumer has large effects on plant community structure on a remote oceanic island, consistent with the viewpoint that strong control by a single species is more likely in simple communities.

Cuticular Proteins from the Lobster, Homarus americanus

The urea-extractable proteins from calcified regions of intermoult cuticle of the lobster, Homarus americanus, have been separated by two-dimensional electrophoresis, showing that the extracts contain a large number of proteins. The major proteins have isoelectric points between 4 and 9, and their apparent molecular weights are between 5 and 30 kDa.Two of the proteins have been purified by a combination of ion-exchange chromatography, gel-filtration and RP-HPLC, and their complete amino acid sequences were determined by a combination of mass spectrometry and automated Edman degradation.Although they were purified from a single animal, both proteins were obtained as two isoforms. The isoforms of the smaller protein (HaCP4.6) differed only in a single position (phenylalanine/isoleucine), and the isoforms of the larger protein (HaCP11.6) differed in two positions (valine/isoleucine and glutamine/lysine). HaCP11.6 is N-terminally blocked by a pyroglutamate residue.Variants of an 18-residue motif are a characteristic feature of both sequences: it occurs twice in HaCP4.6 and four times in HaCP11.6. Comparison of the sequences to sequences published for cuticular proteins from other arthropods shows that the repeated motif is also present in proteins from the exoskeleton of the Bermuda land crab, Gecarcinus lateralis, but not in the single shrimp protein (Pandalus borealis) sequenced so far. The amino acid compositions of the lobster proteins are similar to that of flexible cuticles in locusts, but no convincing sequence similarities were found between the lobster proteins and cuticular proteins from locusts or other insects.

Urate deposits in the gecarcinid land crab Gecarcoidea natalis are synthesised de novo from excess dietary nitrogen

The urate content of the gecarcinid land crab Gecarcoidea natalis was correlated to the amount of nitrogen assimilated. Crabs fed a high-nitrogen diet (ad libitum amounts of soy beans and fig leaves, Ficus macrophylla) for 6 weeks assimilated approximately 23 times more nitrogen (33.9±5.6mmolkg-1day-1) than animals fed a diet low in nitrogen (fig leaves alone) (1.5±0.7mmolkg-1day-1). Animals maintained on a high-nitrogen diet accumulated urate (67.1±29.4mmolkg-1drymass), while animals fed the low-nitrogen diet did not accumulate significant amounts of urate compared with the control animals killed at the beginning of the dietary period. The urate deposits clearly originate from the excess dietary nitrogen ingested on the high-nitrogen diet. The intake of preformed dietary purine was low (0.028±0.005mmolkg-1drymass) and at most could only account for 0.04% of the urate accumulated by crabs fed the high-nitrogen diet. This indicates that the urate was synthesised de novo. When crabs were fed a high-nitrogen diet supplemented with [15N]glycine, the 15N heavy isotope was incorporated into urate. This provided direct evidence that the urate was synthesised de novo.

Associations between shell morphology and land crab predation in the land snail Cerion

1. The land crab Gecarcinus lateralis is a significant predator of the abundant Bahamian land snails of the genus Cerion. The crabs typically ‘scissor’ the cylindrical shells in half or break the lip and peel back the shell to reach the animal which withdraws two or three whorls into the shell. Scars on shells of live adults at 73 sites in the Bahamas and Florida Keys show that about 8% (range: 0–44%) of the snails have survived attacks of this type. 2. An artificial crab claw was used to investigate the compressive force required to break Cerion shells of different morphotypes. Defining shell strength as the ability to withstand compressive forces, 10 morphotypes were found that exhibited mean relative strengths of between 30 and 300 newtons. Feeding trials with one adult crab showed that snails whose shells could withstand compressive forces of > 95 N were safe from this individual predator. 3. Multiple linear regression analyses showed that both shell size (length and width) and shell wall thickness were the ultimate determinants of shell strength. Ribs strengthen the shell by contributing to wall thickness and also by increasing overall shell width. The thickened adult shell lip and collabral ribs provide effective protection from attack by peeling.

University of Washington's radioecological studies in the Marshall Islands, 1946-1977.

Since 1946, personnel from the School of Fisheries, University of Washington (Applied Fisheries Laboratory, 1943-1958; Laboratory of Radiation Biology, 1958-1967; and Laboratory of Radiation Ecology, since 1967), have studied the effects of nuclear detonations and the ensuing radioactivity on the marine and terrestrial environments throughout the Central Pacific. A collection of reports and publications about these activities plus a collection of several thousand samples from these periods are kept at the School of Fisheries. General findings from the surveys show that (1) fission products were prevalent in organisms of the terrestrial environment whereas activation products were prevalent in marine organisms; (2) the best biological indicators of fallout radionuclides by environments were (a) terrestrial-coconuts, land crabs; (b) reef-algae, invertebrates; and (c) marine-plankton, fish. Studies of plutonium and americium in Bikini Atoll showed that during 1971-1977 the highest concentrations of 241Am, 2.85 Bq g(-1) (77 pCi g(-1)) and 239,240Pu, 4.44 Bq g(-1) (120 pCi g(-1)), in surface sediments were found in the northwest part of the lagoon. The concentrations in the bomb craters were substantially lower than these values. Concentrations of soluble and particulate plutonium and americium in surface and deep water samples showed distributions similar to the sediment samples. That is, the highest concentration of these radionuclides in the water column were at locations with highest sediment concentration. Continuous circulation of water in the lagoon and exchange of water with open ocean resulted in removal of 111 G Bq y(-1) (3 Ci y(-1)) 241Am and 222 G Bq y(-1) (6 Ci y(-1)) 239,240Pu into the North Equatorial Current. A summary of the surveys, findings, and the historical role of the Laboratory in radioecological studies of the Marshall Islands are presented.

Density of larval Culicoides belkini (Diptera:Ceratopogonidae) in relation to physicochemical variables in different habitats.

Immature density and population size of the biting midge Culicoides belkini (Wirth & Arnaud) were estimated for habitats on Moorea Island, French Polynesia, by means of random, 2- and 3-stage sampling designs. Samples were taken in March 1993 from 5 strata of a large larval habitat: a sandy-mud surface of approximately 5,000 m2 (stratum 1) in which approximately 12,000 land crab burrows (stratum 2) were counted, a small pond surrounded by approximately 300 m2 of muddy bank (stratum 3), and a high organic muddy area (Kopara) of approximately 1,200 m2 (stratum 4) with approximately 3,500 crab burrows (stratum 5). Larval density was usually higher in the mud of crab burrows, especially those in the Kopara stratum. Larval density was significantly lower in the sediment of the sandy area as compared with pond banks or Kopara surface. The sampling designs and techniques were logistically adequate, statistically relevant, and were recommended for future studies on C. belkini larval density. Larval habitats were characterized by means of multivariate analysis. Comparison of larval densities with selected environmental variables indicated that larvae density was higher in wet sediments with high levels of organic matter (approximately 8% of dry weight of sediment) and low salinity (approximately 0.5-1.5% NaCl equivalents). These variables were considered significant if larval control by means of habitat modification has to be achieved. Nevertheless, C. belkini can tolerate a broad spectrum of variation in the other environmental variables measured and breed in a variety of ecological situations. Therefore, it has a high potential for colonizing new habitats.

Crustacean Muscle Plasticity: Molecular Mechanisms Determining Mass and Contractile Properties

Two crustacean models for understanding molecular mechanisms of muscle plasticity are reviewed. Metabolic changes underlying muscle protein synthesis and degradation have been examined in the Bermuda land crab, Gecarcinus lateralis. During proecdysis, the claw closer muscle undergoes a programmed atrophy, which results from a highly controlled breakdown of myofibrillar proteins by Ca 2+-dependent and, possibly, ATP/ubiquitin-dependent proteolytic enzymes. The advantage of this model is that there is neither fiber degeneration nor contractile-type switching, which often occurs in mammalian skeletal muscles. The second model uses American lobster, Homarus americanus, to understand the genetic regulation of fiber-type switching. Fibers in the claw closer muscles undergo a developmentally-regulated transformation as the isomorphic claws of larvae and juveniles differentiate into the heteromorphic cutter and crusher claws of adults. This switching occurs at the boundary between fast- and slow-fiber regions, and thus the transformation of a specific fiber is determined by its position within the muscle. The ability to predict fiber switching can be exploited to isolate and identify putative master regulatory factors that initiate and coordinate the expression of contractile proteins.

Molecular characterization of four members of the α-tubulin gene family of the Bermuda land crabGecarcinus lateralis

Four alpha-tubulin isoforms recovered from a cDNA library from regenerating limb buds of the Bermuda land crab Gecarcinus lateralis have been characterized. Two clones (alpha 1 and alpha 2) contained complete coding sequences with start and stop codons; the other two clones were partial, lacking 5' ends. The four isoforms showed high homology in their coding sequences but rather low homology in their non-coding regions. Identity between the nucleotide sequences of alpha 1 and alpha 2 was 83.4%; between their predicted amino acid sequences it was 88.9%. The inferred number of amino acid residues for both alpha 1 and alpha 2 was 451, and their calculated molecular weights were 58.29 and 58.45 kDa, respectively. The greatest divergence in the predicted crab alpha-tubulin proteins occurred near the carboxy terminus, as in alpha-tubulins of other organisms. When compared with other species; nucleotide sequences of all four clones showed highest homology to alpha-tubulin genes of an insect (Drosophila melanogaster), while their predicted amino acid sequences were most highly homologous to an alpha-tubulin of a mammal (Rattus norvegicus). Southern blots revealed a total of five to seven alpha-tubulin genes encoded in the G. lateralis genome. Northern blots showed single bands of approximately 2.2 kb with an alpha 1-tubulin probe and 1.9 kb with an alpha 2-tubulin probe. mRNA levels of both tubulin isoforms appeared to be independently regulated at different stages of the intermolt cycle in both epidermis and limb buds. Western blots of 1D gels of proteins from epidermis, limb buds, or claw muscle showed tissue- and stage-specific changes in tubulin content; similar analyses on blots of 2D gels revealed differences in the number of alpha-tubulin isoforms that were expressed.

Molecular characterization of four members of the α‐tubulin gene family of the Bermuda land crab Gecarcinus lateralis

Four α-tubulin isoforms recovered from a cDNA library from regenerating limb buds of the Bermuda land crab Gecarcinus lateralis have been characterized. Two clones (α1 and α2) contained complete coding sequences with start and stop codons; the other two clones were partial, lacking 5′ ends. The four isoforms showed high homology in their coding sequences but rather low homology in their non-coding regions. Identity between the nucleotide sequences of α1 and α2 was 83.4%; between their predicted amino acid sequences it was 88.9%. The inferred number of amino acid residues for both α1 and α2 was 451, and their calculated molecular weights were 58.29 and 58.45 kDa, respectively. The greatest divergence in the predicted crab α-tubulin proteins occurred near the carboxy terminus, as in α-tubulins of other organisms. When compared with other species, nucleotide sequences of all four clones showed highest homology to α-tubulin genes of an insect (Drosophila melanogaster), while their predicted amino acid sequences were most highly homologous to an α-tubulin of a mammal (Rattus norvegicus). Southern blots revealed a total of five to seven α-tubulin genes encoded in the G. lateralis genome. Northern blots showed single bands of approximately 2.2 kb with an α1-tubulin probe and 1.9 kb with an α2-tubulin probe. mRNA levels of both tubulin isoforms appeared to be independently regulated at different stages of the intermolt cycle in both epidermis and limb buds. Western blots of ID gels of proteins from epidermis, limb buds, or claw muscle showed tissue- and stage-specific changes in tubulin content; similar analyses on blots of 2D gels revealed differences in the number of α-tubulin isoforms that were expressed. J. Exp. Zool. 278:63–77, 1997. © 1997 Wiley-Liss, Inc. 1 This article is a US Government work and, as such, is in the public domain in the United States of America.

Respiratory, Acid-Base, and Metabolic Responses of the Christmas Island Blue Crab, Cardisoma hirtipes (Dana), during Simulated Environmental Conditions

The dependency of the Christmas Island blue crab, Cardisoma hirtipes, on fresh water for respiratory gas exchange and transport was investigated in laboratory simulations. The gas exchange rates of air-breathing C. hirtipes were similar to those of other land crabs but decreased to 20% in submerged crabs. Crabs with access to air maintained arterial and pulmonary O2 content (CO2) and partial pressure (PO2), while in submerged crabs the PO2 and CO2 rapidly decreased (by 50%). There was no anaerobiosis, but haemolymph glucose concentration and cardiac output decreased when crabs were submersed, which suggests a hypometabolic state. Submersion induced a metabolic rather than a respiratory alkalosis, and since respiratory gas exchange was low, CO2 excretion to water was unimportant. Cardisoma hirtipes haemocyanin (Hc) has high O2 affinity but low pH sensitivity, which facilitates O2 uptake from hypoxic environments. The high Hc-O2 affinity supports O2 loading but may prevent access to a venous O2 reserve. Calcium, magnesium, and urate, but not L-lactate, were effectors of Hc-O2 affinity. In submerged crabs increased circulating urate maintained haemolymph O2 content. The CO2 capacitance and nonbicarbonate buffering of the haemolymph were relatively low. A significant Haldane effect seemed important for CO2 excretion but would require CO2 and O2 exchange to occur at the same organ (gills or lungs). Submersion interferes with respiration and is not needed for haemolymph acid-base balance; thus; C. hirtipes is an air-breathing crab.

Red crabs in rain forest on Christmas Island, Indian Ocean: activity patterns, density and biomass

ABSTRACTThe red crabGecarcoidea natalisis the most abundant land crab on Christmas Island, Indian Ocean, and is found wherever native rain forest is still intact. The largest crabs grow to > 120 mm carapace width and reach > 500 g in mass. Red crabs are diurnally active, and moisture appears to be the most important factor governing surface activity – activity was nil below 77% RH, relatively low at 87% RH, and high above 95% RH. The crabs retreat to the interior of their burrows during dry periods, but emerge rapidly in response to rain. Because of their dependence on moisture for surface activity, red crabs show greater levels of activity during the wet season. Annual breeding migrations and moulting activity decreased the density of surface-active crabs at the main study sites for several weeks at the start of the wet season, and fruit and leaf fall caused dramatic local increases in the density of active red crabs. Density and biomass at the main study sites averaged 1.3 crabs m-2and 1454 kg ha-1, respectively, and 1.2 crabs m-2and 1137 kg ha-1at a total of five sites across the island. Rough calculations suggest that the island-wide population is at least 100 million individuals. Red crabs are the dominant consumer on the forest floor, and consume seeds, seedlings and leaf litter. Because they are both abundant and widespread, these animals have the potential to be the most important determinant of pattern and process in rain forest on Christmas Island.

Consumption of Bromeliad Flowers By the Crab Metasesarma Rubripes in a Brazilian Coastal Forest

Several crab species have been reported as herbivorous (e.g., Beever et al., 1979; Wolcott & Wolcott, 1987), but flowers have not been mentioned as a food item. In Mexico, Garc?a-Franco et al. (1991) observed pr?dation of bromeliad seeds and seedlings by the land crab Gecarcinus lateralis. Many species of Grapsidae were, however, mentioned as living in bromeliads (Laessle, 1961; McWilliams, 1968; Abele, 1972). In this note, we report bromeliad flowers as food for the crab Metasesarma rubripes (Rathbun, 1897) (Grapsidae). The study was carried out in a coastal rainforest at the Rio Verde estuary, Ecological Station of Jur?ia, south-eastern Brazil (for area description, see Fischer & Araujo, 1995). Metasesarma rubripes occurs in sheltered habitats such as tropical and subtropical salt marshes and estuaries of Central and South America. The species feeds on vegetable debris, mainly roots and stems of Spartina sp. (Capitoli et al., 1977). Individuals live inside burrows built by themselves in muddy substrates, but they can reach stems of trees and epiphytic bromeliads in the adjacent forest (R. C. Nalesso, personal communication). We registered the feeding behavior of the crabs on the inflorescences and ascertained which bromeliad species are used by the crabs throughout the year. We hypothesized that the frequency of crabs per bromeliad species could be affected by the density of flowering plants and/or the density of flowers available. We directly observed individuals of M. rubripes foraging on bromeliad flowers from February 1989 to April 1992. The floral parts eaten and the daylight period in which the crabs were found on the inflorescences were recorded. Some crabs were collected from these inflorescences and the analysis of their gastric con tents confirmed that their diets were composed of flower tissues, mainly pollen. Metasesarma rubripes occurs up to 4 m off the ground (mean = 1.0 m, sd = 0.8, N = 61 records) in the habitats restinga scrub and rocky shore (see Fischer & Araujo, 1995 for habitat descriptions). In both habitats, M. rubripes was com monly found on the forest floor (more frequently the small-sized individuals)