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Low-temperature tolerance of early juveniles of six terrestrial hermit crab species
Abstract
Because temperature strongly influences biological processes of ectotherms, it also plays a fundamental role in determining their geographical distribution. We evaluated the low-temperature tolerance of early juveniles of six terrestrial hermit crab species in the family Coenobitidae (genera Birgus and Coenobita), B. latro, C. brevimanus, C. cavipes, C. purpureus, C. rugosus, and C. violascens that occur in the northwestern Pacific region, Japan. A total of 30 laboratory-raised juveniles (about 1 mm in shield length) carrying gastropod shells were individually stocked in small plastic cups with sandy bottoms in temperature-controlled incubatory chambers at ∼27°C. The temperature was reduced by 1°C every 48 h, and the juveniles were observed until all the crabs had died; the median lethal temperature (MLT) was estimated as the temperature at which 50% of the test juveniles had died. The MLT estimates varied significantly among the species, and the most northward distributed species, C. purpureus, had the lowest MLT values. The phylogeny, paleoceanography, paleogeography, and paleoclimatology suggest that cooler thermal regimes might have acted as an evolutionary force for the divergence of C. purpureus in the Pliocene. A negative correlation was found between the northern latitudinal limit of distribution and the MLT values, even after controlling for the phylogenetic relationships in the six coenobitids. A temperature-dependent biogeography was thus recognized in terrestrial hermit crab species in the northwestern Pacific region, and global warming is expected to affect their geographical distributions.
... Coenobita purpureus has the northernmost geographical distribution (35°N), followed by C. rugosus (31°N) on the Pacific coasts of Japan (Oyake and Fujikawa 2009;Miura 2011). Sanda et al. (2019) evaluated the low-thermal tolerance abilities of laboratory-raised juveniles with ~1 mm shield length (SL) of six coenobitid species that occur in Japan by estimating the median lethal temperature (MLT) at which 50% of the test juveniles die. They found that the most northward distributed species, C. purpureus, had the lowest MLT values, and the MLT estimates significantly decreased with increasing latitude toward the northern limit of the geographical distributions of the six coenobitid species. ...
... The reproductive season of coenobitid crabs occurs in summer in Japan (KPBE 1987;OPBE 1987;Nakasone 2001;Fujikawa et al. 2017). The differences in air temperature are small (< 3.5°C) in summer throughout the geographical distribution of coenobitids in Japan, whereas the winter temperatures decrease in accordance with northward latitudes, and their maximum difference is approximately 13°C (Sanda et al. 2019). Therefore, it can be hypothesized that, after landing, early juveniles might die, depending on species-specific low-temperature tolerance properties during the overwintering period, leading to the current biogeographical pattern of coenobitid species. ...
... In the present study, the overwintering period of coenobitid crabs was defined as the period from November to April when the mean air temperature was generally below 18°C, because many coenobitid juveniles cease feeding below ~18°C (Sanda et al. 2019). To infer the temperature environments of the early juvenile habitats during the overwintering period, the air temperature was recorded every 15 min with a data logger (Thermochron SL, KN Laboratories Co. Ltd., Osaka, Japan) at all sites except Katsuura from December 1, 2013 to March 11, 2014, and at all sites from November 1 to December 22, 2014. ...
The present study aimed to elucidate the population dynamics of land hermit crabs on the coast of the Boso Peninsula, Chiba Prefecture, Japan, which is the northern limit of their geographical distribution. We conducted monthly field surveys at four sites from April 2012 to December 2014 and visually searched for crabs. Laboratory experiments were also conducted to evaluate the overwintering ability of two species, Coenobita purpureus and C. rugosus, which were detected during the field surveys; adult crabs and laboratory-raised juveniles were exposed to low-temperature conditions that simulated the in situ temperatures during the early overwintering period. Newly landed juveniles first appeared in August. They were identified as either C. purpureus or C. rugosus, with C. purpureus being the dominant species. Early juveniles grew until October. The abundance of early juveniles decreased with decreasing air temperatures, and dead individuals were found during the overwintering period. The low-temperature tolerance ability of C. purpureus was stronger than that of C. rugosus. Some crabs successfully overwintered, and all were identified as C. purpureus. The growth and overwintering success of juveniles varied among the survey sites depending on the local temperature regime. Our results highlight the frontier for expanding the northern geographical distribution of land hermit crab populations by the colonization and overwintering success of C. purpureus.
... Considering the most northward distribution of C. purpureus in the northwestern Pacific region, it is hypothesized that C. purpureus might have adapted to relatively cooler thermal environments. Sanda et al. (2019) tested this hypothesis by comparing the lower thermal tolerance ability of laboratory-raised juveniles with ∼1 mm SL of six coenobitid species that occur in Japan. The low-temperature tolerance was evaluated by estimating the median lower lethal temperature (MLLT) at which 50% of the test juveniles had died. ...
... brevimanus), or two broods (other species) were separately cultured. Zoeae, megalopae, and juvenile crabs were cultured according to the methods of Hamasaki et al. (2013Hamasaki et al. ( , 2014 and Sanda et al. (2019). Metamorphosis to megalopae occurred from late July to early September (table 1). ...
... To explore whether the upper thermal tolerance limits vary with latitudinal distribution in the test coenobitid crabs, the relationship between the northern limit of geographical distribution, summarized by Sanda et al. (2019), and mean MULT values estimated by the present study for respective species was evaluated with a linear regression analysis using the lm function. In the present study, we do not have to consider the southern limit of distribution as an explanatory variable in this analysis because the test coenobitid species excluding C. purpureus are widely distributed in subtropical and tropical coastal regions including areas around the equator (Hartnoll, 1988;Nakasone, 1988;Poupin, 1996;Becchi et al., 2015;Hamasaki et al., 2015c;Rahayu et al., 2016). ...
Because temperature strongly influences biological processes of ectotherms, they must adapt to the thermal conditions of their habitats. We evaluated the upper thermal tolerance of early juveniles of six terrestrial hermit crab species in the family Coenobitidae (genera Birgus and Coenobita ), B. latro , C. brevimanus , C. cavipes , C. purpureus , C. rugosus , and C. violascens , that occur in the northwestern Pacific region of Japan. A total of 30 laboratory-raised juveniles (approximately 1 mm in shield length) carrying gastropod shells were individually stocked in small plastic cups with sandy bottoms in temperature-controlled incubation chambers at ∼27°C. The temperature was increased by 1°C every 48 h, and the juveniles were observed until all the crabs had died. The median upper lethal temperature was estimated as the temperature at which 50% of the test juveniles had died. The median upper lethal temperature estimates significantly varied among the species. Coenobita violascens , which mainly occurs in mangrove estuaries with lower thermal conditions, had the lowest median upper lethal temperature values. The median upper lethal temperature values estimated for B. latro were slightly lower than those for the other Coenobita species, probably reflecting its cryptic nature in natural habitats during the juvenile stage. The most northerly distributed species, C. purpureus , had the highest median upper lethal temperature values, suggesting the existence of common physiological mechanisms that regulate both upper and lower thermal tolerance abilities.
There is currently a strong scientific consensus that recent global change of climate, including the global warming, seriously damage ecosystems of both lands and oceans. Here, I review recent drastic northern expansion of distribution of tropical land hermit crabs (Coenobita) into temperate Japan. Seto Marine Biological Laboratory of Kyoto University has a long history (97 years) and has been conducting various programs of long-term monitoring survey on coastal biota. A part of the results is also introduced here. Seventeen species of land hermit crabs are known from tropical regions worldwide, and seven species are known in Japan, which are mainly distributed in tropical region of Japan. Recent intensive studies on coastal areas of Japan have shown that many juveniles and small individuals of land hermit crabs are found during warm season in temperate regions. The finding of the species that were identified by DNA analysis as Coenobita rugosus and C. purpureus might be an indication for the global warming effect. Further, I here introduce the model of northern limit of distribution proposed by Gorodkov (1986) which explains change of detailed structure of population toward the limit of distribution. Moreover, I here propose the model of stages of adaptation of tropical species to temperate zone through ecological and evolutional times. These two models are useful and helpful to understand the things happen in populations in the limit of distribution and, therefore, useful for conservation of species and biological communities.
Temperature is an important environmental factor affecting the larval survival, development and duration of decapod crustaceans. We investigated the effect of temperature on larval performance in six terrestrial hermit crab species (genera Birgus and Coenobita): B. latro, C. brevimanus, C. cavipes, C. purpureus, C. rugosus, and C. violascens. Larvae were cultured at six temperature levels between ~19 and 34 °C. Larvae could not survive to the megalopal stage at temperatures below 20 °C. Megalopae appeared at temperatures above ~22-23 °C, and survival rates to the megalopal stage were high at ~25-31 °C and tended to decline over ~32 °C. Intra-and interspecific variations were found in the developmental pathways to the megalopal stage: 4 zoeal stages in B. latro, 4-8 zoeal stages in C. cavipes and 4 or 5 zoeal stages in the other Coenobita species. The proportions of larvae that completed the shorter developmental pathways tended to increase with increasing temperature in each species. Total zoeal duration tended to decrease with increasing temperature in all species, and C. cavipes, with prolonged developmental pathways, exhibited the longest developmental periods to the megalopal stage. The lower threshold temperature for larval development was estimated to be 16.4-19.3 °C based on the heat summation theory equation. Thus, larvae of coenobitid crabs are not able to develop and survive at low-temperature conditions below 20 °C, exhibiting typical thermal adaptation of subtropical and tropical species.
The present study investigated the distributions of land hermit crabs on the coasts of Miura Peninsula and Boso Peninsula, Japan. Crabs were collected through visual surveys during the summer from 2015-2017, and early juveniles just after landing were also collected from the survey site on the Miura Peninsula. Overwintering large individuals of Coenobita purpureus were found and one ovigerous female of C. purpureus was detected from the survey site on each peninsula. Early juveniles of C. purpureus and C. rugosus were detected and C. purpureus was dominant in the specimens (62%) collected on the Miura Peninsula as previously reported by our study conducted on the Boso Peninsula. Consequently, C. purpureus and C. rugosus migrated to the Miura Peninsula and Boso Peninsula, and only C. purpureus successfully overwintered and grew to reproduce.
The present study investigated the distributions of terrestrial hermit crabs on Hatomajima Island, Ryukyu Archipelago, Japan. Crabs were collected through visual surveys during daytime and nighttime and using bait traps overnight from 22 to 24 June, and from 11 to 13 September 2013 at 17 localities. The coconut crab Birgus latro and four species belonging to the genus Coenobita, i.e., C. brevimanus, C. cavipes, C. purpureus, and C. rugosus were recorded. Coconut crabs were captured on and/or near limestone shores, and in an inland cave. C. brevimanus lurked in coastal and inland forests during daytime and showed nocturnal activity. C. cavipes were also captured in coastal and inland forests, and they were all immature. C. rugosus were dominant on seashore. A few C. purpureus were also captured on seashore.
The present study investigated the distributions of terrestrial hermit crabs along the coasts of Ishigakijima Island and Iriomotejima Island, Ryukyu Archipelago, Japan. Crabs were collected through visual surveys during daytime and nighttime from late June to early July during 2011 and 2012 at 18 localities on Ishigakijima Island, as well as through visual surveys during daytime and nighttime and using bait traps overnight in early July 2014 at 10 localities on Iriomotejima Island. Additionally, to confirm the temporal distributions of the crabs, nighttime visual surveys were conducted in late August and early October 2012 at 2 localities on Ishigakijima Island. Crabs were identified to the species level, and their body sizes were measured. On both islands, the coconut crab Birgus latro and five species belonging to the genus Coenobita, i.e., C. brevimanus, C. cavipes, C. purpureus, C. rugosus, and C. violascens, were recorded. Coconut crabs were captured on and/or near the limestone shores. Coenobita species excluding C. violascens were collected from the several localities that cover the entire coasts of the islands; in particular, C. rugosus, which was the dominant species, composed approximately 80% of the total number of collected individual crabs at almost all the localities on the islands. The distribution of C. violascens was restricted to the vicinity of the river, and these crabs mainly inhabited the mangrove estuaries. Our results highlight the importance of protecting mangrove estuaries to conserve the C. violascens populations.
We evaluated the thermal adaptations of embryos of 6 terrestrial hermit crab species in the family Coenobitidae (genera Birgus and Coenobita): B. latro, C. brevimanus, C. cavipes, C. purpureus, C. rugosus, and C. violascens. Embryos of each species were cultured in vitro at 6 different temperatures (18 to 34°C) in artificial seawater to avoid air desiccation; the lower threshold temperatures for embryonic development were estimated using heat summation theory equations. Additionally, partial effective cumulative temperatures (> lower threshold temperature) until hatching were determined for ovigerous females of each species cultured in containers. The relationships between the embryonic growth index values (relative area of the embryonic body vs. total embryo surface) and effective cumulative temperatures were expressed using cubic equations. Lower threshold temperature was estimated to be 12.7 to 14.5°C. The effective cumulative temperature and egg incubation period estimates from the appearance of the embryonic body to hatching were higher in B. latro and C. brevimanus, followed by C. rugosus, C. cavipes, and C. violascens, and lower in C. purpureus, suggesting that C. brevimanus may retain an ancestral thermal adaptation trait for embryos, as in B. latro, which is considered the most ancestral species in the coenobitid phylogeny. Egg size varied among species but did not affect the thermal adaptations of embryos. The lower effective cumulative temperature and shorter egg incubation period may be advantageous to producing broods during the shorter summer breeding season in C. purpureus, which has the northern-most geographical distribution.
A new species of land hermit crab in the genus Coenobita Latreille, 1829 from Singapore, Malaysia and Indonesia, previously confused with C. cavipes Stimpson, 1858 (Crustacea: Decapoda: Anomura: Coenobitidae) Abstract. A new species of land hermit crab in the genus Coenobita Latreille, 1829 (Anomura: Coenobitidae), C. lila, is described from Singapore and adjacent countries. The new species has previously been confused with C. cavipes Stimpson, 1858, but they can be distinguished by the former possessing dense tubercles on the outer face of the palm of the left cheliped and the presence of a large sternal protuberance between the male fifth pereopods. Recognition of the new species is further supported by molecular data. In this study, the presence of C. cavipes in Taiwan is confirmed, and the status of C. baltzeri Neumann, 1878, is discussed.
A tenet of macroecology is that physiological processes of organisms are linked to large-scale geographical patterns in environmental conditions. Species at higher latitudes experience greater seasonal temperature variation and are consequently predicted to withstand greater temperature extremes. We tested for relationships between breadths of thermal tolerance in ectothermic animals and the latitude of specimen location using all available data, while accounting for habitat, hemisphere, methodological differences and taxonomic affinity. We found that thermal tolerance breadths generally increase with latitude, and do so at a greater rate in the Northern Hemisphere. In terrestrial ectotherms, upper thermal limits vary little while lower thermal limits decrease with latitude. By contrast, marine species display a coherent poleward decrease in both upper and lower thermal limits. Our findings provide comprehensive global support for hypotheses generated from studies at smaller taxonomic subsets and geographical scales. Our results further indicate differences between terrestrial and marine ectotherms in how thermal physiology varies with latitude that may relate to the degree of temperature variability experienced on land and in the ocean.
The Kuroshio Current is a major western boundary current controlled by the North Pacific Gyre. It brings warm subtropical waters from the Indo-Pacific Warm Pool to Japan exerting a major control on Asian climate. The Tsushima Current is a Kuroshio offshoot transporting warm water into the Japan Sea. Various proxies are used to determine the paleohistory of these currents. Sedimentological proxies such as reefs, bedforms, sediment source and sorting reveal paleocurrent strength and latitude. Proxies such as coral and mollusc assemblages reveal past shelfal current activity. Microfossil assemblages and organic/inorganic geochemical analyses determine paleo-sea surface temperature and salinity histories. Transportation of tropical palynomorphs and migrations of Indo-Pacific species to Japanese waters also reveal paleocurrent activity. The stratigraphic distribution of these proxies suggests the Kuroshio Current reached its present latitude (35 °N) by ~3 Ma when temperatures were 1 to 2 °C lower than present. At this time a weak Tsushima Current broke through Tsushima Strait entering the Japan Sea. Similar oceanic conditions persisted until ~2 Ma when crustal stretching deepened the Tsushima Strait allowing inflow during every interglacial. The onset of stronger interglacial/glacial cycles ~1 Ma was associated with increased North Pacific Gyre and Kuroshio Current intensity. This triggered Ryukyu Reef expansion when reefs reached their present latitude (~31 °N), thereafter the reef front advanced (~31 °N) and retreated (~25 °N) with each cycle. Foraminiferal proxy data suggests eastward deflection of the Kuroshio Current from its present path at 24 °N into the Pacific Ocean due to East Taiwan Channel restriction during the Last Glacial Maximum. Subsequently Kuroshio flow resumed its present trajectory during the Holocene. Ocean modeling and geochemical proxies show that the Kuroshio Current path may have been similar during glacials and interglacials, however the glacial mode of this current remains controversial. Paleohistorical studies form important analogues for current behavior with future climate change, however, there are insufficient studies at present in the region that may be used for this purpose. Modeling of the response of the Kuroshio Current to future global warming reveals that current velocity may increase by up to 0.3 m/sec associated with a northward migration of the Kuroshio Extension.
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 move-ments, 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. Ob-served 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 varia-tions in expected future mating opportunities within the reproductive season and male reproductive strategy in re-sponse to these variations.
Climate change is altering phenology and distributions of many species and further changes are projected. Can species physiologically adapt to climate warming? We analyse thermal tolerances of a large number of terrestrial ectotherm (n = 697), endotherm (n = 227) and plant (n = 1816) species worldwide, and show that tolerance to heat is largely conserved across lineages, while tolerance to cold varies between and within species. This pattern, previously documented for ectotherms, is apparent for this group and for endotherms and plants, challenging the longstanding view that physiological tolerances of species change continuously across climatic gradients. An alternative view is proposed in which the thermal component of climatic niches would overlap across species more than expected. We argue that hard physiological boundaries exist that constrain evolution of tolerances of terrestrial organisms to high temperatures. In contrast, evolution of tolerances to cold should be more frequent. One consequence of conservatism of upper thermal tolerances is that estimated niches for cold-adapted species will tend to underestimate their upper thermal limits, thereby potentially inflating assessments of risk from climate change. In contrast, species whose climatic preferences are close to their upper thermal limits will unlikely evolve physiological tolerances to increased heat, thereby being predictably more affected by warming.
This paper analyzes the phylogeographical patterns of amphibian and reptile lineages distributed in the Ryukyu islands south
of the Tokara Gap on the basis of relevant distributional data and phylogenetic hypotheses hitherto published. Results indicate
the numerical dominance of highly relict lineages in the central Ryukyus, and the occurences of a few more or less relict
lineages in the Miyako Group as well. On the other hand, most species and subspecies endemic to the Yaeyama Group or to the
Yaeyama and Miyako Groups are considered to be direct consequences of vicariance with adjacent regions. Three major hypotheses
regarding the Cenozoic paleogeography of the central and the southern Ryukyus are examined in the light of the present results
and a modified hypothesis is proposed accordingly.
Land hermit crabs are scavengers that use olfaction to locate their foods. Although they are scavengers, land hermit crabs do not select their foods randomly. This study demonstrates that land hermit crabs (Coenobita compressus H. Milne Edwards) display negative preference induction when feeding on natural foods, preferring foods that they have not experienced recently. These induced feeding preferences were measured at a population level by recording crab choices among food odors in the field with olfactory attraction assays. When the abundances of foods in their habitat were altered, crabs preferred the odors of foods that were less abundant. Induced feeding preferences were measured at an individual level by recording crab choices among 3 foods in a laboratory choice assay. Crabs more frequently chose foods that they had not experienced during the previous 24 h. As a consequence of this behavior, land hermit crabs consume a broader diet, which may result in crabs obtaining a more nutritionally balanced diet or limiting their exposure to toxins.
Recent years have shown a rise in mean global temperatures and a shift in the geographical distribution of ectothermic animals. For a cause and effect analysis the present paper discusses those physiological processes limiting thermal tolerance. The lower heat tolerance in metazoa compared with unicellular eukaryotes and bacteria suggests that a complex systemic rather than molecular process is limiting in metazoa. Whole-animal aerobic scope appears as the first process limited at low and high temperatures, linked to the progressively insufficient capacity of circulation and ventilation. Oxygen levels in body fluids may decrease, reflecting excessive oxygen demand at high temperatures or insufficient aerobic capacity of mitochondria at low temperatures. Aerobic scope falls at temperatures beyond the thermal optimum and vanishes at low or high critical temperatures when transition to an anaerobic mitochondrial metabolism occurs. The adjustment of mitochondrial densities on top of parallel molecular or membrane adjustments appears crucial for maintaining aerobic scope and for shifting thermal tolerance. In conclusion, the capacity of oxygen delivery matches full aerobic scope only within the thermal optimum. At temperatures outside this range, only time-limited survival is supported by residual aerobic scope, then anaerobic metabolism and finally molecular protection by heat shock proteins and antioxidative defence. In a cause and effect hierarchy, the progressive increase in oxygen limitation at extreme temperatures may even enhance oxidative and denaturation stress. As a corollary, capacity limitations at a complex level of organisation, the oxygen delivery system, define thermal tolerance limits before molecular functions become disturbed.
Analysis of Phylogenetics and Evolution (APE) is a package written in the R language for use in molecular evolution and phylogenetics.
APE provides both utility functions for reading and writing data and manipulating phylogenetic trees, as well as several advanced
methods for phylogenetic and evolutionary analysis (e.g. comparative and population genetic methods). APE takes advantage
of the many R functions for statistics and graphics, and also provides a flexible framework for developing and implementing
further statistical methods for the analysis of evolutionary processes.
Availability: The program is free and available from the official R package archive at http://cran.r-project.org/src/contrib/PACKAGES.html#ape. APE is licensed under the GNU General Public License.
The larval release behaviour of Coenobita cavipes Stimpson, 1858 was studied on Iriomote Island, Japan between June and September 2012. The larval release was observed for several days before and after the new and full moons between July and August and showed semi-lunar rhythms. The larval release occurred 1-3 h after sunset and the peak time was almost 30 min earlier in August than in July. The time was not synchronised with nocturnal high tides in earlier and later days in each phase of syzygy. Emerging from residual lowland forests behind the coast, ovigerous females walked towards the river's water edge and released larvae at the swash zone on the riverbank in the lower river. Therefore, they do not need to synchronise the larval release to coincide with the timing of high tide, unlike their congeneric nearest neighbour, C. violascens Heller, 1862, which releases larvae on the mangrove roots in the upper river.
Terrestrial hermit crabs in the family Coenobitidae (genera Coenobita and Birgus) are distributed in tropical and subtropical regions. They occupy various habitats ranging from shore to inland forests, and the two shore-dwelling species, Coenobita rugosus and C. violascens, possess different distributional characteristics on Ishigakijima Island, Ryukyu Archipelago, Japan. Coenobita rugosus is distributed throughout the coast of the island and is abundant in beach areas, whereas C. violascens has mainly been found in river mouth areas. However, very little is known about the habitats used by the early life stages of coenobitid crabs because identifying the species of recently landed early juveniles is difficult. We tested whether the species compositions of early juveniles of coenobitids differed between beach and river mouth sites on Ishigakijima Island. We collected and identified the early stage coenobitids using PCR–RFLP techniques. A total of 576 early juveniles of five Coenobita species were collected, of which 0.7% were C. brevimanus, 7.3% were C. cavipes, 0.2% were C. purpureus, 70.1% were C. rugosus, and 21.7% were C. violascens. The early juveniles of Birgus latro were not found. The early juveniles of C. rugosus occurred at both beach and river mouth sites, and they were abundant at beach sites. The early juveniles of C. violascens were only found at river mouth sites. These findings indicate that C. rugosus and C. violascens complete their life cycles on land near the localities where they land. The early juveniles of the inland-dwelling species, C. cavipes, were also mainly collected from river mouth sites, which suggested that juveniles of C. cavipes selected landing sites near river mouth areas and then migrated into the inland forests, passing through riverside areas. Our results highlighted the importance of river mouth areas for recruitment to adult habitats by some coenobitid species.
Hermit 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.
Larval releasing behavior of Coenobita violascens Heller, 1862 was studied on a mangrove forest on the banks of a river on Iriomote Island, Japan (24°25′N, 123°46′E) between May and October 2012 and July and September 2014. Larval release was observed on the mangrove root systems, boulders, and fallen trees on the riverbanks. Behaviors from tree climbing to larval release began during nighttime at low tide when ovigerous females approached mangrove trees on the intertidal shore and climbed trees to heights of 0.2-1.6 m. After climbing, they rested on the trunk under the leaf canopy or under the root system to avoid direct sunlight during the day and descended to the roots near the water line following the nighttime high tide. Females immersed themselves fully or partially in river water and released the hatching zoea larvae. Larval release was observed for several days before and after the new moon between July and October and occurred only after sunset; larval release coincided well with high tide. For this species, which is adapted to mangrove habitats, larval release on mangrove roots with tree climbing and clear lunar and tidal rhythms enhances the probability of as many larvae as possible reaching the sea with a receding tide.
Terrestrial hermit crabs in the family Coenobitidae (genera Coenobita and Birgus) must migrate onto land after completing a pelagic larval stage in the ocean. Better knowledge of emigration behavior would assist in the conservation and management of coenobitid populations by helping identify and protect the habitats they need to complete their life cycles. We cultured laboratory-born individuals of five coenobitid species (Coenobita cavipes, C. purpureus, C. rugosus, C. violascens, and Birgus latro) from megalopae to early juveniles (first, second, and/or third crabs) in vessels containing seawater and a hard substrate, and analyzed their behavior and molting in conjunction with our published data for C. brevimanus. Our results confirm that the coenobitids migrated from sea to land at the megalopal stage. Megalopae and early juveniles tended to select shells based on their body size. Inland-dwelling coenobitids, such as C. brevimanus, C. cavipes, and B. latro, had a longer duration from landing to first molt and had a prolonged first crab intermolt period compared with those of the beach-dwelling coenobitids C. purpureus, C. rugosus, and C. violascens, probably because of the adaptive traits for migrating to inland habitats. Little burrowing behavior was observed by megalopae of B. latro, but they had a strong tendency to be cryptic under shelters. Additionally, megalopae and early juveniles of Coenobita spp. created and utilized burrows somewhat differently. Our results suggest that coenobitids require specific microhabitats for completing their early life stages in the wild. In particular, megalopae of B. latro may need structurally complex refuges to migrate from the sea.
The objective of this study was to examine the distribution of juvenile Birgus latro (L). The field research was conducted on the terrace of the eastern part of the island of Lifou in the Loyalty Islands. The terrace, which was once the surrounding reef, has since been raised along with the raising of the atoll. Located between the ocean and the former reef crown, which is now the cliff, the terrace encircles the island. Juvenile crabs were only found under coconut piles at the foot of coconut trees. The largest juvenile crabs collected had a thoracic length (TL) of 28 mm. The number of crabs in coconut piles decreased rapidly above 23 mm TL, which is approximately the size of sexual maturity. No adults were found under coconut piles, as their principal habitat was in burrows located in the calcareous rock beyond the terrace. The smallest juvenile crabs were found near the ocean and the largest close to the cliff-face. During their first terrestrial stages, juvenile coconut crabs carried three kinds of terrestrial gastropod shells according to their size. Those with a TL of less than 2 mm mostly chose Draparnaudia sp., those with a TL between 2 and 4 mm preferred Achatina fulica and those between 4 and 7 mm used Achatina fulica and Placostylus sp. shells with a preference for the latter. All crabs captured ≤7 mm TL (n = 32; means size = 3.7 ± SD 1.4 mm) had a shell, as opposed to all those over 7.8 mm TL (n = 50; mean size = 16.5 ± SD 5.2 mm) which no longer did.
We investigated patterns of larval growth and development in terrestrial hermit crabs of the family Coenobitidae (genera Coenobita and Birgus). Larvae of 5 species (C. cavipes, C. purpureus, C. rugosus, C. violascens, and B. latro) were cultured individually at ~28°C, and their moulting, growth and developmental duration were analysed in conjunction with published data for coenobitid species (C. brevimanus, C. cavipes, C. clypeatus, C. compressus, C. purpureus, C. rugosus, C. scaevola, C. variabilis, and B. latro). Coenobitid crabs metamorphosed into megalopae after 2 to 7 zoeal stages, and intraspecific variability in developmental pathways (number of zoeal stages) was observed in 6 out of 10 species. Interspecific variability in body lengths was large at hatching but reduced in megalopae. Linear growth equations (y = a + bx) between number of moults (x) and body length (y) in the zoeal stages were determined, parameters a and b representing body length at hatching and mean growth increment at moulting, respectively. The relationship between parameters a and b for the species examined suggested the existence of 4 larval growth and development patterns in coenobitids: (1) initially smaller larvae and smaller growth increments—longer pathway; (2) initially smaller larvae and larger growth increments—shorter pathway; (3) initially larger larvae and smaller growth increments—shorter pathway; and (4) initially largest larvae and smallest growth increments—shortest pathway (abbreviated development). Total zoeal duration increased with decreasing water temperatures and increasing number of zoeal stages and was apparently unrelated to the geographical distribution of coenobitid species.
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.
Populations of the coconut crab, Birgus latro (Linnaeus, 1767), have been depleted by overharvesting and environmental degradation. The aim of this study was to develop artificial propagation technologies for the restocking and conservation of this species. Coconut crabs migrate from the sea to land as megalopae, carrying gastropod shells. We examined the effects of sea-water availability and the timing of their involuntary migration from sea to land on the survival and moulting of megalopae and juveniles by culturing them individually in containers with dry "land" but with or without aquatic "sea areas." The schedule of their involuntary migration to the land in the test containers was set at ages of 5 and 10 days after metamorphosis to the megalopal stage, and at ages between 12 and 16 days, when the megalopae walked steadily while wearing a shell. The treatments did not affect the moulting of the animals. The animals survived in the containers with seawater areas. In contrast, all those in the containers without sea areas died, and severe mortality occurred after the animals moulted to the crab stage, suggesting that water availability may protect the animals from desiccation in air during and after ecdysis. Old megalopae (10 days old) appeared to be more active than young megalopae (5 days old) in walking and manipulating shells at first landing, although the three different schedules of migration to land did not affect the survival of the animals. Our results highlight the importance of water availability in culturing coconut crab juveniles.
1. Terrestrial ectotherms are likely to face increased periods of heat stress as mean temperatures and temperature variability increase over the next few decades. Here, we consider the extent to which changes in upper thermal limits, through plasticity or evolution, might be constrained, and we survey insect and reptile data to identify groups likely to be particularly susceptible to thermal stress.
2. Plastic changes increase thermal limits in many terrestrial ectotherms, but tend to have less effect on upper limits than lower limits.
3. Although comparisons across insect species have normally not taken into account the potential for plastic responses, mid-latitude species seem most prone to experience heat stress now and into the future, consistent with data from lizards and other groups.
4. Evolutionary adaptive potential has only been measured for some species; there is likely to be genetic variation for heat responses in populations, but selection and heritability experiments suggest that upper thermal limits may not increase much.
5. Although related species can differ by several degrees in their upper thermal limits, there is strong phylogenetic signal for upper limits. If these reflect evolutionary constraints, substantial molecular changes may be required to increase upper thermal limits.
6. Findings point to many terrestrial ectotherms having a limited potential to change their thermal limits particularly within the context of an average predicted temperature increase of 2–4 °C for mid-latitude populations over the next few decades.
The complete larval development of the Australian terrestrial hermit crab Coenobita variabilis McCulloch is described from laboratory-reared specimens. Development consists of two brief, nonfeeding zoeal stages and one megalopal stage. The megalopal stage does feed, but will metamorphose only on land. This is the first case of abbreviated development known in the Coenobitidae. Both zoeal stages exhibit character development typical of all stages of other coenobitids, allowing for easy identification of the species but preventing a clear determination of which stages were eliminated during the evolution of the abbreviated developmental mode. Compared to known megalopae of other coenobitids, the megalopa shows no evidence of advanced development.
Populations of the coconut crab, Birgus latro, have been severely depleted on most inhabited islands throughout the Indo-Pacific because of over-harvesting and environmental degradation. Coconut crabs emigrate from the sea as megalopae carrying gastropod shells. Better knowledge of emigration behaviour can assist in conservation of coconut crab populations through understanding and protecting the habitats indispensable for completing their life cycle. We examined the behaviour of coconut crabs during sea-to-land transition by culturing megalopae and juveniles in containers that hold sea-water and hard substrate simulating an intertidal microhabitat in nature. The test environmental factors were availability of gastropod shells and substrata (small and coarse coral sands) including shelters on land, and humidity (relative humidity, 76% and 98%). Megalopae matured their nature for acquiring shells and emigration from the sea in around 10days. Humidity and shell availability affected animal behaviour. Low humidity decreased the proportion of animals on land, and burrowing behaviour was stimulated in low humidity and shell-less conditions. Animals in low humidity had a low survival rate. Shelters and shells stimulated the proportion of animals on land at low humidity, and animals concentrated under the shelters on land. Shells, burrows and shelters should act to protect animals from desiccation by keeping microclimates around animals on high humidity. Thus, coconut crab megalopae and juveniles preferred a humid environment, and high-humidity conditions stimulated emigration from the sea. Our findings highlight the importance of a humid environment around the seashore in sustaining the recruits for coconut crab populations.
Based upon surface marine climatic evolution on both sides of the Pacific Ocean recently revealed by biochronostratigraphy in Japan and South America, the tectonics of Pacific Ocean seaways and associated responses of adjacent seas and ocean currents are discussed. The rapid opening of the Sea of Japan at about 15 Ma in early Middle Miocene time, mainly by the rotation of the Southwest Japan arc, can be correlated with the abrupt appearance of a cold-water fauna on the Pacific coast of Northeast Japan beginning ca. 15 Ma and an extensive hiatus along the Pacific coast of southwestern Japan spanning 15 Ma to 12 Ma. The abrupt and extensive development of biosiliceous lithofacies along the Pacific coast of Peru beginning about 14 Ma might also represent a response to the tectonic anticlockwise rotation of the Peruvian Block of the Andean Mountain Range, estimated to have occurred sometime during the Miocene. As the tectonic closing of the Indonesian seaway would have strongly intensified the warm Kuroshio current in the Northwest Pacific, it is most probable that this seaway was effectively closed just prior to 15.5 Ma in the earliest Middle Miocene, when tropical marine faunas were developed in most of the Japanese Islands. The closing of the Central American seaway is estimated to have been completed at 3.5-3 Ma in Pliocene time. The closure of this seaway would likely have intensified the warm Kuroshio current, affecting the marine fauna along the Pacific coast of southwestern Japan. It is also possible that a decrease in surface temperatures at about 3 Ma along the Pacific coast of Ecuador was due to this Pliocene tectonic event.
From a bibliographic compilation and, to a lesser extent, from material collected in the field, 401 littoral and sublittoral decapods (Palinura, Anomura, Brachyura), are reported from French Polynesia. The Brachyura prevail, with 313 species, mainly Xanthidae (123 species), Portunidae (54 species), and Grapsidae (35 species). The Anomura are represented by 74 species, and the Palinura by only 14 species. The list of the deep species, ie living in depths of 100m or more, is updated. Ninety-two species are listed, making a total of 493 Polynesian species. Amongst the material recently collected, 16 species are recorded for the first time in the area: Calcinus guamensis, Calcinus imperialis, Dardanus australis, Dardanus brachyops, Albunea speciosa, Parthenope contrarius, Portunus macrophthalmus, Portunus orbitosinus, Thalamita danae, Thalamita macropus, Thalamita mitsiensis, Thalamita philippinensis, Quadrella maculosa, Planes cyaneus, Percnon guinotae, and Macrophthalmus serenei. Moreover, after the examination of the type material, Ruppelia granulosa A. Milne Edwards, 1867, originally describe from the Marquesas, is here proposed as a junior synonym of Lydia annulipes (H. Milne Edwards, 1834). Only 8 species, related to well defined species, are known solely from French Polynesia: Parribacus holthuisi, Micropagurus polynesiensis, Nucia rosea, Nursia mimetica, Acanthophrys cristimanus, Lissocarcinus elegans, Ozius tricarinatus, and Macrophthalmus consobrinus. For some of them, however, it is probable that their distributions extend at least to western Polynesia. The French Polynesian fauna is typically Indo-West Pacific in its composition, with few endemic forms, and a low diversity compared to the Indo-Malaysian area. It includes, however, many more species than the Hawaiian fauna, possibly because the Polynesian islands are less isolated than the Hawaiian islands. The Society, Tuamotu, and Gambier archipelagos have been well investigated, with numerous expeditions organised in these areas. In contrast, the Austral and Marquesas Islands, still remain poorly known. The French Polynesian fauna is more or less homogenous, with few regionally distinctive features. The single obvious exception is for the isolated southernmost islands, Rapa and Marotiri, subjected to a subtropical climate. In these islands, species that are very common elsewhere, are missing (Coenobita perlatus, Birgus latro, Cardisoma carnifex), and, on the contrary, at least one common species is still unknown in the northern part of French Polynesia (Panulirus pascuensis).
About five to four million years ago, in the early Pliocene epoch, Earth had a warm, temperate climate. The gradual cooling that followed led to the establishment of modern temperature patterns, possibly in response to a decrease in atmospheric CO2 concentration, of the order of 100 parts per million, towards preindustrial values. Here we synthesize the available geochemical proxy records of sea surface temperature and show that, compared with that of today, the early Pliocene climate had substantially lower meridional and zonal temperature gradients but similar maximum ocean temperatures. Using an Earth system model, we show that none of the mechanisms currently proposed to explain Pliocene warmth can simultaneously reproduce all three crucial features. We suggest that a combination of several dynamical feedbacks underestimated in the models at present, such as those related to ocean mixing and cloud albedo, may have been responsible for these climate conditions.
With intensified harvesting and environment deterioration during the past two decades, a rapid decline in the number of coconut crabs, Birgus latro, which is a protected species listed in the IUCN Invertebrate Red Data Book, has occurred on many islands. Thus, it is important to protect this species by establishing conservation areas and/or replenish natural population by larval cultivation. In this study, the development modes were analyzed and the effect of enriched diet on larval growth and survival were examined. Two types of zoeal development patterns were found. In general, zoeae took 29-33 days to complete five zoeal stages and metamorphose to glaucothoes. However, some zoeae directly metamorphosed from the 3rd zoeal to glaucothoe stage in 2528 days. Morphologically, these zoeae with accelerated development had thoracic appendages that appeared like the fifth stage zoeae, but with the telson, antennule, and antenna similar to those of the third stage zoeae. When fed Artemia nauplii enriched with nutritious substances, the zoeae had significantly greater survivorship and sizes, particularly at the fourth and fifth zoeal stages. Accelerated development may suggest early adaptation to a terrestrial lifestyle. The adaptation of larval development related to glaucothoe size and zoeal life span is also compared and discussed for eight terrestrial hermit crab species of Coenobitidae. The comparison suggests four adaptive modes of larval development and these are described as mangrove adaptation, larger glaucothoe adaptation, smaller glaucothoe adaptation, and hypersaline adaptation. The selective advantage of each mode may reflect a response to the uniqueness of each specific habitat.
Information about reproductive season, size at sexual maturity and size-dependent reproductive potentials is important for efficient resource management. Such information is necessary to determine seasonal closures and minimum legal size limits. To conserve resources of coconut crab Birgus latro, which are in danger of extinction due to excessive exploitation, their reproductive season, female size at functional maturity and relationship between female size and reproductive potentials were investigated. The reproductive season started in early June and ended late August, and females with higher reproductive potentials showed a tendency to spawn early in the reproductive season. The prohibition of exploiting the resources during the reproductive season, especially early in the season, would be appropriate for sustainability of high reproductive outputs. Fifty percent of investigated females matured functionally at 24.5-mm thoracic length (TL). However, the size at which all females reached functional maturity was 32.3 mm TL, and there was a wide variation in the size of functional maturity among individuals. We must determine minimum legal size by taking the variation into account to allow all individuals to mate at least once before they are caught, which may prevent serious depression in reproductive rate and genetic diversity.
Populations of the coconut crab, Birgus latro, have been severely depleted on most inhabited islands throughout Indo-Pacific regions because of overharvesting and environmental degradation. To assist in the development of artificial propagation technologies for restocking/stock enhancement of this species, this study was designed to elucidate the effect of rearing temperature on survival and developmental period of zoeae through a laboratory experiment testing six constant temperatures levels (18.9, 21.3, 24.6, 27.0, 29.8, and 32.4 °C). Mortality of all first stage zoeae occurred at 18.9 °C. In contrast, the survival rate to the megalopal stage was significantly higher (85.6 and 82.2%) at 27.0 and 29.8 °C, respectively, than all other treatments. Temperature also had marked effects on larval developmental periods. The number of days from hatching required to reach each larval stage (D) significantly decreased with increasing temperature (T). The mean duration from hatching to the megalopal stage ranged between ~ 19 and 23 days at appropriate temperatures for larval survival (27.0 and 29.8 °C).
The marine megalopa of the terrestrial hermit crab Coenobita compressus wears a small gastropod shell that it carries onto land before metamorphosing into a juvenile crab. This paper gives the first detailed account of temporal shifts in shell-related behaviors that occur as the megalopa approaches metamorphosis. Megalopae placed in individual containers shortly after metamorphosing from the last zoeal stage exhibited three behaviors: shell inspection, followed by shell wearing in water, and finally by shell wearing on land. Megalopae experimentally denied access to shells exited the water at about the same time as megalopae with shells, but they wandered about on land for shorter periods of time before burying themselves in sand and attempting to metamorphose. Once buried, megalopae without shells often emerged and re-buried themselves at other locations in their containers; almost all shell-less megalopae died without metamorphosing to the first juvenile crab stage. Once buried, megalopae with shells rarely emerged without first metamorphosing to the juvenile crab stage, and they metamorphosed significantly more frequently than those denied shells.
Comparative studies of the relationship between 2 phenotypes, or between a phenotype and an environment, are frequently carried out by invalid statistical methods. Most regression, correlation, and contingency table methods, including nonparametric methods, assume that the points are drawn independently from a common distribution. When species are taken from a branching phylogeny, they are manifestly nonindependent. Use of a statistical method that assumes independence will cause overstatement of the significance in hypothesis tests. Some illustrative examples of these phenomena are given, and limitations of previous proposals of ways to correct for the nonindependence discussed. A method of correcting for the phylogeny is proposed. It requires that we know both the tree topology and the branch lengths, and that we be willing to allow the characters to be modeled by Brownian motion on a linear scale. Given these conditions, the phylogeny specifies a set of contrasts among species, contrasts that are statistically independent and can be used in regression or correlation studies. -from Author
We discuss and clarify several aspects of applying Felsenstein's (1985, Am. Nat. 125: 1–15) procedures to test for correlated evolution of continuous traits. This is one of several available comparative methods that maps data for phenotypic traits onto an existing phylogenetic tree (derived from independent information). Application of Felsenstein's method does not require an entirely dichotomous topology. It also does not require an assumption of gradual, clocklike character evolution, as might be modeled by Brownian motion. Almost any available information can be used to estimate branch lengths (e.g., genetic distances, divergence times estimated from the fossil record or from molecular clocks, numbers of character changes from a cladistic analysis). However, the adequacy for statistical purposes of any proposed branch lengths must be verified empirically for each phytogeny and for each character. We suggest a simple way of doing this, based on graphical analysis of plots of standardized independent contrasts versus their standard deviations (i.e., the square roots of the sums of their branch lengths). In some cases, the branch lengths and/or the values of traits being studied will require transformation. An example involving the scaling of mammalian home range area is presented. Once adequately standardized, sets of independent contrasts can be analyzed using either linear or nonlinear (multiple) regression. In all cases, however, regressions (or correlations) must be computed through the origin. We also discuss ways of correcting for body size effects and how this relates to making graphical representations of relationships of standardized independent contrasts. We close with a consideration of the types of traits that can be analyzed with independent contrasts procedures and conclude that any (continuous) trait that is inherited from ancestors is appropriate for analysis, regardless of the mechanism of inheritance (e.g., genetic or cultural).
Reproductive ecological research on three land hermit crabs, Coenobita rugosus, C. purpureus, and C. cavipes, was conducted in the southern part of Okinawa-jima island in 1985, 1986, 1987, and for a short period in 1999. Size (carapace length) of the smallest ovigerous female was 3.93 mm for C. rugosus, 3.83 mm for C. purpureus, and 9.49 mm for C. cavipes. Breeding season is late May to November for C. rugosus, late May to mid-September for C. purpureus, and mid-May to late August for C. cavipes. Some females of all three species probably produced at least two broods during the breeding season. The smallest males in which spermatophores were present in dissected vas deferens were 4.24 mm for C. rugosus and 4.94 mm for C. purpureus. Coenobita cavipes females produced more, smaller eggs in comparison with C. purpureus. My observations suggest that coenobitid crabs living in areas with a low supply of shells or with poor shells reproduce at smaller sizes, as is the case in marine hermit crabs. Time of onset of larval release by C. rugosus, with its protracted breeding season, varied according to the seasonal shift in time of sunset. The period during which females of C. rugosus released larvae was about 2 hr in spring tides but was much longer (3 to 5 hr) during neap tides. Larger females of C. purpureus occupied shells derived from the land snail Achatina fulica; smaller ones used shells from the marine snail Lunella granulata. Use of mutually exclusive larval release sites by the larger and smaller females of C. purpureus remained unchanged over 13 yr, from 1986 to 1999. This behavioral difference may be related to the differences in their habitats (i.e., inland versus shore) and to the route traveled by the larger crabs in reaching the sea from inland sites.
Terrestrial hermit crabs (Coenobita spp.) were observed feeding on a variety of food items corresponding with observations on the genus worldwide . A field experiment was conducted which examined (1) the feeding activity of Coenobita in two habitats and (2) their potential impact on the removal of carrion and on the colonization of carrion by fly maggots. Habitat and time of day influenced the size and species of Coenobita feeding. Large C. perlatus fed only at night and had the greatest impact on the carrion. Although small Coenobita had little effect on the carrion, their feeding activity did reduce the number of fly maggots in the carrion. The scavenging activity of hermit crabs may serve a useful role on inhabited islets. The rapid removal of carrion would reduce potential fly breeding sites.
The coconut crab. Birgus latro (L.) emigrates from the sea during the postlarval glaucothoe stage. Glaucothoes show ancestral
hermit crab behavior of living in empty gastropod shells which protect them during this vulnerable time.
The Coconut Crab: Aspects of Birgus latro
- I W Brown
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HelpersMG: tools for Earth Meteorological Analysis
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Ecology of the land hermit crab Coenobita purpureus on Kikaijima Island. I. Breeding site, breeding season and migration
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On land hermit crabs in Kii Peninsula
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The origin of the Ryukyu Islands
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Rediscovery of juveniles of Coenobita sp. (Crustacea, Anomura) in autumn in 2011 at "Kitahama beach
- S Kubota
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