Crab Birgus Latro Research Articles

Characterization of the complete mitochondrial genome of a coconut crab, Birgus latro (Linnaeus, 1767) (Decapoda: Anomura: Coenobitidae), from Okinawa, Japan

AbstractWe present a full description and analysis of the complete mitochondrial genome of a Pacific Ocean specimen of the coconut crab Birgus latro (Linnaeus, 1767), the largest extant terrestrial arthropod in the world. Our de novo-assembled mitogenome has a massive 16,161 times organelle read coverage, a length of 16,411 bp, contains 22 tDNAs (20 unique), 13 protein-coding genes, two rDNAs, and a putative control region of length 1,381 bp. The control region contains three microsatellites and two pairs of inverted repeats. Contrary to the mitochondrial sentinel gene concept, two-dimensional nucleotide analysis reveals higher GC-content in cox gene families than in nadh gene families. Moreover, cox gene families are more conserved than nadh gene families among the species of Coenobitidae selected for comparison. Secondary structure prediction of the 22 tDNAs shows major deviations from the cloverleaf pattern, which points to a relatively high rate of mutation in these genes. We also present a repertoire of mitochondrial variation between our male Okinawan coconut crab and an Indian Ocean specimen that consists of one insertion, one deletion, 135 SNPs, three MNPs and nine complex polymorphisms. We provide confirmatory evidence that the superfamily Paguroidea, to which the coconut crab belongs, is polyphyletic, that all the protein-coding genes of B. latro are under purifying selection, and that a Pacific versus Indian Ocean coconut crab population divergence occurred during the Pleistocene.

A case study of the coconut crab Birgus latro on Zanzibar highlights global threats and conservation solutions

Abstract The coconut crab Birgus latro, the largest terrestrial decapod, is under threat in most parts of its geographical range. Its life cycle involves two biomes (restricted terrestrial habitats near the coast, and salt water currents of the tropical Indian and Pacific Oceans). Its dependence on coastal habitat means it is highly vulnerable to the habitat destruction that typically accompanies human population expansion along coastlines. Additionally, it has a slow reproductive rate and can reach large adult body sizes that, together with its slow movement when on land, make it highly susceptible to overharvesting. We studied the distribution and population changes of coconut crabs at 15 island sites in coastal Tanzania on the western edge of the species' geographical range. Our aim was to provide the data required for reassessment of the extinction risk status of this species, which, despite indications of sharp declines in many places, is currently categorized on the IUCN Red List as Data Deficient. Pemba Island, Zanzibar, in Tanzania, is an important refuge for B. latro but subpopulations are fragmented and exploited by children and fishers. We discovered that larger subpopulations are found in the presence of crops and farther away from people, whereas the largest adult coconut crabs are found on more remote island reserves and where crabs are not exploited. Remoteness and protection still offer hope for this species but there are also opportunities for protection through local communities capitalizing on tourist revenue, a conservation solution that could be applied more generally across the species' range.

A crustacean annotated transcriptome (CAT) database

BackgroundDecapods are an order of crustaceans which includes shrimps, crabs, lobsters and crayfish. They occur worldwide and are of great scientific interest as well as being of ecological and economic importance in fisheries and aquaculture. However, our knowledge of their biology mainly comes from the group which is most closely related to crustaceans – insects. Here we produce a de novo transcriptome database, crustacean annotated transcriptome (CAT) database, spanning multiple tissues and the life stages of seven crustaceans.DescriptionA total of 71 transcriptome assemblies from six decapod species and a stomatopod species, including the coral shrimp Stenopus hispidus, the cherry shrimp Neocaridina davidi, the redclaw crayfish Cherax quadricarinatus, the spiny lobster Panulirus ornatus, the red king crab Paralithodes camtschaticus, the coconut crab Birgus latro, and the zebra mantis shrimp Lysiosquillina maculata, were generated. Differential gene expression analyses within species were generated as a reference and included in a graphical user interface database at http://cat.sls.cuhk.edu.hk/. Users can carry out gene name searches and also access gene sequences based on a sequence query using the BLAST search function.ConclusionsThe data generated and deposited in this database offers a valuable resource for the further study of these crustaceans, as well as being of use in aquaculture development.

Sex Ratio and Growth Pattern of Coconut Crabs <i>Birgus latro</i> (Crustacea, Decapoda, Cianobitidae) in North Moluccas Province, Indonesia

Coconut crab (Birgus latro) is a crustacean that has a large size until four kilograms. The study aimed to analyze sex ratio and growth pattern including the relationship of thorax length - body weight, thorax width - body weight and cephalothorax length plus rostrum - body weight in Daeo (Morotai Island), Laigoma (South Halmahera District) and Fitako (North Halmahera District). The sex ratio was determined using χ2 test and the growth pattern was tested by the b value through t test. The results showed sex ratio of 1: 0.9 in Daeo (n = 581), 1: 0.6 in Laigoma (n = 24), and 1: 2 in Fitako (n = 31). The relationship of thorax length, thorax width and cephalothorax length plus rostrum with body weight were strongly correlated (R2> 70%). The growth pattern of coconut crab in Daeo was negative allometric, while in Laigoma and Fitako were negative allometric and isometric.

Acetoin is a key odor for resource location in the giant robber crab Birgus latro.

The terrestrial and omnivorous robber crab Birgus latro inhabits islands of the Indian Ocean and the Pacific Ocean. The animals live solitarily but occasionally gather at freshly opened coconuts or fructiferous arenga palms. By analyzing volatiles of coconuts and arenga fruit, we identified five compounds, including acetoin, which are present in both food sources. In a behavioral screen performed in the crabs' habitat, a beach on Christmas Island, we found that of 15 tested fruit compounds, acetoin was the only volatile eliciting significant attraction. Hence, acetoin might play a key role in governing the crabs' aggregation behavior at both food sources.

Giant coconut crab stalks and kills bird

A coconut crab has been spotted hunting and devouring a seabird. It is the first time coconut crabs have been seen actively hunting large animals, and suggests they rule their island homes. Coconut crabs (Birgus latro), or robber crabs; are imposing. They can weigh up to 4 kilograms, as much as a house cat, and sport legs that span almost a metre. This makes them the largest invertebrates--animals without backbones--on land. The crabs live on coral atolls in the tropical Indian and Pacific oceans. Between January and March 2016, Mark Laidre of Dartmouth College in New Hampshire visited the Chagos Archipelago, a remote series of atolls in the Indian Ocean. Chagos is ideal for studying coconut crabs: it is in pristine condition, is surrounded by one of the largest marine reserves on earth and has lots of coconut crabs, making them easier to find and observe.

Phylogeny and phylogeography of the land hermit crab Coenobita purpureus (Decapoda: Anomura: Coenobitidae) in the Northwestern Pacific Region

AbstractHermit crabs of the family Coenobitidae comprise the land hermit crabs, with 16 Coenobita species, and the coconut crab Birgus latro. They are terrestrial but spend their marine life as planktonic larvae. Some coenobitid crabs are widely distributed in the Indo‐West Pacific region, and some species occupy narrower ranges. To improve our knowledge of coenobitid crab speciation and geographical distribution patterns, we examined the phylogenetic relationship between Coenobita purpureus, which has a narrow distribution in the Northwestern Pacific, and its more widely distributed coenobitids including B. latro, Coenobita brevimanus, Coenobita cavipes, Coenobita perlatus, Coenobita rugosus and Coenobita violascens based on the mtDNA cytochrome c oxidase subunit I (COI) and 16S rDNA genes. We also assessed the phylogeography of Co. purpureus populations based on the COI gene. Our phylogenetic and phylogeographical analyses revealed that (i) Co. purpureus clustered with Co. rugosus and (ii) the Co. purpureus population in the Ogasawara Islands was genetically distinct from those in other regions, which showed genetic panmixia. It has been hypothesized that Co. purpureus evolved in the isolated landmasses of the Ryukyu region during the Pliocene, and that its population expanded and colonized the Ogasawara Islands in the late Pleistocene. Further phylogeographical studies on Coenobita species with relatively narrow distributions coupled with characterization of their phylogenetic relationships with widely distributed congeners will advance our knowledge of the speciation and geographical distribution history of coenobitid crabs.

Effects of long-term frozen storage on the compositions of free amino acids and nucleotide-related compounds of the coconut crab Birgus latro

This study examined the effects of long-term frozen storage (-20 °C for 5 months) of free amino acids (FAAs) and nucleotide-related compounds (NRCs) in muscle and hepatopancreas of the coconut crab Birgus latro. Although long-term frozen storage had little effect on FAA composition in muscle, the amounts of several FAAs increased in the hepatopancreas that may be the result of protein decomposition during the frozen storage. Long-term storage at -20°C significantly increased the amounts of disodium 5ʹ-inosine monophosphate (IMP) in muscle and hepatopancreas, resulting from the deaminase activity of 5ʹ-adenosine monophosphate (AMP) which deaminates AMP to IMP. Changes in FAAs and NRCs may result in changes in the flavor of muscle and hepatopancreas of frozen stored coconut crabs, both through altered amounts of each substance and synergistic interactions among substances.

Evidence for a single panmictic and genetically diverse population of the coconut crab Birgus latro (Decapoda: Anomura: Coenobitidae) on Christmas Island in the Indian Ocean

For the coconut crab Birgus latro, Christmas Island in the Indian Ocean may be one of the last retreats where populations of this declining species are not threatened by overharvesting, as on many other mostly tropical Indo-Pacific islands within the species’ wide range. Nevertheless, the population on Christmas Island has experienced severe losses during the past decade owing to habitat destruction and road mortality. To assess the population’s evolutionary potential and identify the number of conservation units, we conducted a combined morphometric and population genetic analysis using microsatellite markers. The findings suggest that the population is genetically diverse and panmictic. Neither genetic nor morphometric analyses revealed any population substructuring. There was no genetic evidence for sex-biased dispersal. Single-sample estimators for the effective population size (Ne) ranged from 492 to infinity, with very wide confidence intervals; they should therefore be viewed with caution. It would be advisable to reanalyse Ne, preferably by temporal methods. Despite mixed results, there is stronger evidence against rather than for the occurrence of a recent genetic bottleneck. So far, the population of B. latro on Christmas Island may be considered as a single conservation management unit, this way simplifying future conservation efforts taken for this magnificent species.

Seasonal variations in free amino acids, nucleotide-related compounds, and fatty acids and meat yield of the coconut crab Birgus latro

This study analyzed seasonal variations in meat yield and compositions of free amino acids (FAA), nucleotide-related compounds (NRC), and fatty acids in muscle and hepatopancreas of the coconut crab Birgus latro of Okinawa, southwest Japan. A conspicuous increase in total meat yield was observed during September to November, prior to molting in the winter dry season. Although both total FAA and NRC content in muscle and hepatopancreas did not vary significantly by seasons, the taste activity value of methionine in muscle was larger than 1 only during September to November. Seasonal variations in equivalent umami concentration (EUC) were greater in muscle than in the hepatopancreas, with the EUC of muscles highest in September to November. Although fatty acid compositions of muscle and hepatopancreas did not change significantly seasonally, amounts of total fatty acids, saturated fatty acids, and monounsaturated fatty acids in muscle and hepatopancreas, and amount of n-3 polyunsaturated fatty acids in the hepatopancreas, were significantly greater in September to November. These results indicate the best season to eat coconut crab is September to November. These findings may contribute to a premium value for this resource and promote resource conservation of this species.

Settlement behavior and substrate preference of the coconut crab Birgus latro megalopae on natural substrata in the laboratory

Although they are land dwellers, coconut crabs, Birgus latro, spend planktonic larval development in the sea and immigrate to the land as megalopae carrying gastropod shells. Better knowledge of settlement behavior and habitat requirements during the early life stages can assist in conservation of depleted coconut crab populations. Our objectives were to evaluate settlement behavior of coconut crab megalopae from 0 to 6dpost-metamorphosis (dpm), and determine the substrate preference (open sand, coral fragments, or brown algae) of 0–12dpm megalopae. Early megalopae (0–3dpm) were active swimmers during the night. The walking activity of naked megalopae was directly correlated with shell-inspection behavior during the day, peaking at 2–3dpm. Almost all megalopae wore shells by 5dpm and the walking activity of megalopae wearing shells was higher during the night than the day. Based on our observations, we hypothesize that megalopae migrate to the coast by nocturnal flood-tide transport and emigrate from the sea during the nocturnal full tidal phase to minimize predation risk. In the substrate choice experiment, early megalopae exhibited no preference for any substrata, and shell-less megalopae experienced the highest mortality, probably because of cannibalism. The survival rate plateaued at 9dpm associated with an increase in the proportion of individuals wearing shells and of the onset of active habitat selection for complex substrata (coral fragments or brown algae). This suggests that shells and structural complex habitats are important for survival during the initial benthic phase of the coconut crab.

Differences in compositions of free amino acids, nucleotide-related compounds, and fatty acids between sexes of the coconut crab Birgus latro in Okinawa, Southwest Japan

Despite the dietary utilization of the coconut crab Birgus latro throughout history, little is known about its nutritional composition and quality. This study assessed the differences between male and female coconut crabs caught in Okinawa, southwest Japan, in meat yield and compositions of free amino acids (FAA), nucleotide-related compounds (NRC), and fatty acids in muscle and hepatopancreas. The ratios of edible muscle and hepatopancreas to whole body weight were similar in males and females. Although concentrations of histidine and tryptophan in muscle and AMP in hepatopancreas differed in males and females, these differences were small, as were taste activities and equivalent umami concentrations, suggesting that the tastes of these tissues in males and females would be nearly identical. Fatty acid composition in muscle differed lightly between the sexes, with amounts of the 20:5n-3 and 22:6n-3 being significantly greater in males. However, the ratio of n-3 to n-6 polyunsaturated fatty acids and atherogenic and thrombogenic indices suggested that all lipids from both males and females are healthy for humans. There were no noticeable differences between the sexes in meat yield; FAA, NRC and fatty acid compositions; or nutritional qualities.

Survival and growth of juveniles of the coconut crab Birgus latro under laboratory conditions: implications for mass production of juveniles

Populations of the coconut crab, Birgus latro (Linnaeus, 1767), have been depleted by primarily overharvest. The aim of this study was to develop artificial propagation technologies for the restocking and conservation of this species: it is a terrestrial hermit crab with aquatic larvae. Megalopae (post-larvae stage) were group cultured for six months with access to both “land” and “sea” areas (trial 1). In addition, shell-carrying juveniles aged one month were group cultured on land until the age of 13 or 24 months (trial 2). Furthermore, juveniles that had abandoned their gastropod shells were cultured individually and their moult and growth was monitored. The survival rates of animals ranged from 26-55% in trial 1, and they grew to a mean thoracic length (TL) of approx. 1 mm. In trial 2, the juveniles grew to a mean TL of approx. 4 mm at age 24 months. The juveniles changed their gastropod shells for larger ones according to their growth based on their body width. The juveniles found soon after abandoning their gastropod shells varied in size (2.5-8.6 mm TL), age (15-26 months old), and the degree of the formation of pleonal tergal plates. The juveniles without shells moulted 5-6 times during the culture period of 9-20 months. Two survivors grew to 6.8 mm TL and 11.9 mm TL at an age of 24 and 37 months, respectively. The body colour pattern of the juveniles was retained through successive moults. Our results demonstrated the feasibility of artificial production of the coconut crab juveniles and the utility of using natural marks to monitor their growth and migration after being released in the wild.

Larval development and emigration behaviour during sea-to-land transition of the land hermit crab Coenobita brevimanus Dana, 1852 (Crustacea: Decapoda: Anomura: Coenobitidae) under laboratory conditions

To determine the early life history of the land hermit crab Coenobita brevimanus Dana, 1852, larvae were cultured individually in the laboratory. The zoeal and the megalopal stages are described and illustrated. The larvae developed through four planktonic zoeal stages to the megalopal stage. The major differences in the zoeal characters between C. brevimanus and other described Coenobita species were found in the armature of the pleomeres, whereas the character of pleomeres of C. brevimanus zoeae is the same as that of the coconut crab Birgus latro, a different genus in the same family. Morphological similarity was also found in segmentations of antennules and antennae in megalopae between C. brevimanus and the coconut crab. Megalopae of C. brevimanus were cultured in containers holding seawater and a hard substrate. These crabs migrate from the sea to land after developing a habit of acquiring gastropod shells.

Factors influencing growth of giant terrestrial robber crab Birgus latro (Anomura: Coenobitidae) on Christmas Island

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 19:129-141 (2013) - DOI: https://doi.org/10.3354/ab00523 Factors influencing growth of giant terrestrial robber crab Birgus latro (Anomura: Coenobitidae) on Christmas Island Michelle M. Drew1,*, Michael J. Smith2, Bill S. Hansson1 1Max Planck Institute for Chemical Ecology, Hans Knoell Strasse 8, 07745 Jena, Germany 21/10 Leonora St, Como, Western Australia 6798, Australia *Email: myobatrachid@hotmail.com ABSTRACT: Birgus latro has significant conservation and socio-economic importance throughout its range, yet very little is known about its growth in its natural habitat. An extensive mark-recapture program was undertaken on Christmas Island, Australia, in which over 1440 individual crabs were uniquely identified using passive integrated transponder (PIT) tags. Over 18% of the tagged population was recaptured at least once and remeasured, providing substantial information on growth of B. latro. Our results show that in its natural setting B. latro is a very slow-growing species. Individuals commonly experience conditions that result in zero or negative growth. Sex, size, and injury all strongly influence the crab’s moult increment. Males approached zero growth at around 65 mm in thoracic length (TL), while growth in females started to plateau at around 50 mm TL. Injury frequently led to negative growth, particularly in individuals that had lost a claw and/or multiple limbs—presumably due to a loss of foraging opportunities or access to other resources and a redistribution of available energy into limb regrowth. Our study indicates that previous growth curves do not adequately describe the growth of B. latro in its natural setting and that individual crabs may live over 30 yr longer than previously predicted, with large crabs likely to be over 100 years old. This may have serious implications for the long-term conservation of the species in the face of continuing exploitation. KEY WORDS: Birgus latro · Growth · Moult increment · Mark-recapture · PIT tag · Conservation Full text in pdf format PreviousNextCite this article as: Drew MM, Smith MJ, Hansson BS (2013) Factors influencing growth of giant terrestrial robber crab Birgus latro (Anomura: Coenobitidae) on Christmas Island. Aquat Biol 19:129-141. https://doi.org/10.3354/ab00523 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 19, No. 2. Online publication date: September 24, 2013 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2013 Inter-Research.

Growth of the coconut crab Birgus latro estimated from mark-recapture using passive integrated transponder (PIT) tags

Determination of the growth pattern of a harvested species is an important step toward a proper assessment and suitable management of the stock. Although coconut crab Birgus latro populations in most regions have been severely depleted, few reliable biological data are available. We assessed the growth of B. latro using a mark-recapture method based on the use of passive integrated transponder (PIT) tags on Hatoma Island, located southwest of Okinawa, Japan. Of 781 crabs tagged (337 males, 444 females; 14.89 to 58.03 mm thoracic length (ThL)), 17 males and 20 females were recaptured. The application of PIT tags provided field data for growth of individuals for up to 2326 d and confirmed that coconut crabs molt during the winter dry season on Hatoma Island. The curves relating ThL with age, estimated from data of 29 crabs that had spent one or multiple winter dry seasons at liberty, showed that the coconut crab is an extremely slow growing species, with males showing much higher mean asymptotic ThL (69.87 mm) than females (42.79 mm). The Brody growth coefficient (K)was 0.061 yr �1 for males and 0.091 yr �1 for females. This study is the first to provide growth estimates of wild coconut crabs based on mark- recapture over multiple years. Potentially long-lived, slow growing species such as coconut crabs may be susceptible to overharvesting, and a cautious approach is recommended to the determina- tion of resource management regimes for B. latro.

Ontogeny of sinking velocity, body density, and phototactic behaviour in larvae of the coconut crab Birgus latro: Implications for larval dispersal and recruitment in the sea

As a basis for understanding the larval dispersal and recruitment processes of the coconut crab, Birgus latro, in the sea, we examined the ontogenetic changes in the passive sinking velocity, body density, and phototactic behaviour to different light intensities and wavelengths of the zoeal and megalopal stages of laboratory-reared larvae. Six levels of light intensity, from 310μmolm−2s−1 to 0.0031μmolm−2s−1 in 10% decrements, and 14 light wavelengths in the range of 400–660nm in 20nm increments were tested. The controls were tested in the dark. The coconut crab larvae showed negative buoyancy. The mean sinking velocity was 7.5mms−1 in the first zoeal stage, which increased significantly to ~10mms−1 after the third zoeal stage. The mean body density was 1.085–1.089gcm−3 in the first to third zoeal stages; it then decreased significantly to 1.072–1.075gcm−3 in the fourth zoeal and megalopal stages. This ontogenetic pattern in body density differs from those of other decapod crustacean species and may be related to the emigration behaviour of the megalopae from the sea to the land. The coconut crab larvae were generally photopositive, with the strength of their positive phototactic behaviour decreasing at lower light intensities and with age. Higher incidences of positive phototactic behaviour were recorded at spectra of 400–660nm, 400–620nm and 400–600nm for the first, second, and third zoeal stages, respectively. The spectral sensitivity of the fourth zoeal stage showed peaks at around 400–420nm and 500–580nm, suggesting that the larval distribution in the sea changes at the fourth zoeal stage. The overall phototactic behaviour of the megalopae was weak, and the behavioural responses varied at light wavelengths above 520nm. Thus, their phototactic behaviour may have little effect on their migration to the coast.

Reproductive migration of the coconut crab Birgus latro

Knowledge of movement patterns is essential in tailoring spatial conservation and management measures. Although populations of the coconut crab, Birgus latro, have been severely depleted in most habitats, there have been few serious attempts to manage the resources. Recently, spatial conservation (e.g. seasonal area closure) has been suggested as an effective tool for resource management. However, relatively little is known about coconut crab movements, especially reproductive migration. To determine the dynamics of the reproductive migration of coconut crabs, we investigated both male and female migration patterns during the reproductive season in Hatoma Island, southwest of Japan. Both females and males migrated between inland and coastal areas during the reproductive season. Observed female seaward and landward migrations were temporally coincident with their reproductive activities (egg extrusion and larval hatching). Observed temporal-spatial distribution of males would be shaped by temporal variations in expected future mating opportunities within the reproductive season and male reproductive strategy in response to these variations.

Impacts of Large Male-Selective Harvesting on Reproduction: Illustration with Large Decapod Crustacean Resources

To signal a need for caution for present large male-selective harvesting practices, negative impacts of the large male-selective harvesting on reproductive output in large decapod crustacean resources are introduced with emphasis on my own work with spiny king crab Paralithodes brevipes, coconut crab Birgus latro, and the stone crab Hapalogaster dentata. The large male-selective harvestings for several large decapod crustaceans have changed their population demographic structure by decreasing mean male size and skewing sex ratio towards females. By several field and laboratory experiments, the change of population demographic structure was anticipated to decrease female reproductive success in the resources (i.e. reproductive output of the harvested populations) through a decrease in sperm availability for females because of male size-dependent reproductive potentials and slow sperm recovery rate. Furthermore, reproductive output and stability of the large male-selective harvested resources were also anticipated to decline by a decrease in mate availability for females, attributing to combination of female mate choice for larger males with negative effects of female delayed mating and/or maternal influences. To establish the optimal management practices, the details of the mating system and reproductive ecology of each targeted species should be investigated.

Giant Robber Crabs Monitored from Space: GPS-Based Telemetric Studies on Christmas Island (Indian Ocean)

We investigated the navigational capabilities of the world's largest land-living arthropod, the giant robber crab Birgus latro (Anomura, Coenobitidae); this crab reaches 4 kg in weight and can reach an age of up to 60 years. Populations are distributed over small Indo-Pacific islands of the tropics, including Christmas Island (Indian Ocean). Although this species has served as a crustacean model to explore anatomical, physiological, and ecological aspects of terrestrial adaptations, few behavioral analyses of it exist. We used a GPS-based telemetric system to analyze movements of freely roaming robber crabs, the first large-scale study of any arthropod using GPS technology to monitor behavior. Although female robber crabs are known to migrate to the coast for breeding, no such observations have been recorded for male animals. In total, we equipped 55 male robber crabs with GPS tags, successfully recording more than 1,500 crab days of activity, and followed some individual animals for as long as three months. Besides site fidelity with short-distance excursions, our data reveal long-distance movements (several kilometers) between the coast and the inland rainforest. These movements are likely related to mating, saltwater drinking and foraging. The tracking patterns indicate that crabs form route memories. Furthermore, translocation experiments show that robber crabs are capable of homing over large distances. We discuss if the search behavior induced in these experiments suggests path integration as another important navigation strategy.