BULLETIN OF MARINE SCIENCE, 75(1): 27–35, 2004

27Bulletin of Marine Science© 2004 Rosenstiel School of Marine and Atmospheric Science of the University of Miami

THE IMPORTANCE OF SHELL OCCUPATION AND SHELL AVAILABILITY IN THE HERMIT CRAB PAGURUS

BREVIDACTYLUS (STIMPSON, 1859) (PAGURIDAE) POPULATION FROM THE SOUTHERN ATLANTIC

Fernando Luis Mantelatto and Andrea de Lucca Meireles

ABSTRACTGastropod shell availability and utilization by the hermit crab Pagurus brevidactylus

(Stimpson, 1859) at Anchieta Island, Brazil, were determined as part of a long-term ef-fort to understand the dynamics of hermit crab shell utilization. All shells occupied by these hermits, found empty, or with live gastropods were collected monthly, from Janu-ary–December 2000, by SCUBA divers. A total of 3704 gastropod shells of 32 species was collected (1528 were occupied by crabs, 1943 had live gastropods, and 233 were empty). Shells of two of the four most common gastropod species in the field [Cerith-ium atratum (Born, 1778) and Morula nodulosa (C.B. Adams, 1845)] were also the most occupied by P. brevidactylus. The morphometric relationships that best describe the association between hermits and their shells were those involving the dimensions of the crabs and shell internal volume and dry weight. The shell occupation pattern of P. brevidactylus is correlated with shell availability in the field, although the hermits also have the capacity to select shells according to their dimensions.

Although hermit crabs occupy objects other than gastropod shells (Gherardi and Cas-sidy, 1995; Mantelatto and Souza-Carey, 1998), gastropod shells are clearly important in all aspects of their life cycle as the main source utilized by these crustaceans to pro-tect their soft and vulnerable abdomen (see Mantelatto and Garcia, 2000 for review). This resource can prove a limiting factor in hermit crab population dynamics, affecting both population size and the rates of individual growth, reproduction, development, and longevity (Raimondi and Lively, 1986; Lancaster, 1988; Mantelatto and Garcia, 1999). Thus, studies of shell availability in the field are necessary in explaining shell occupa-tion patterns by hermit crabs.

The variables by which a particular shell is chosen by a hermit crab are not well known. Almost every physical variable has been considered as being of primary impor-tance: shell weight (Hazlett and Herrnkind, 1980), its weight/volume ratio (Markham, 1968), the angle of its columellar axis (Dowds and Elwood, 1983), the relationship be-tween hermit weight and shell width (Vance, 1972a), the internal volume of the shell, its rugosity, aperture size or shape, and even its internal architecture (Lancaster, 1988). Many shell variables have been shown to be important to different species of hermit crabs (Reese, 1962; Conover, 1978; Blackstone, 1985; Wilber, 1990; Manjón-Cabeza and García Raso, 1999; Rodrigues et al., 2000). Shell selection by hermit crabs, is not by chance, but is based on the adequacy and availability of resources to the hermit crabs (Reese, 1962; Conover, 1978; Garcia and Mantelatto, 2000). Furthermore, the suitability of a particular shell might not be the same for different species of hermits, reflecting several selection pressures associated with different habitats (Bertness, 1981a).

As part of a long-term effort undertaken to identify and clarify the association between hermit crab and gastropod shells, this study was designed to characterize the gastropod shell availability and the occupation patterns of the hermit crab Pagurus brevidactylus (Stimpson, 1859), inhabiting the infralittoral area of Anchieta Island, southern Brazil.

BULLETIN OF MARINE SCIENCE, VOL. 75, NO. 1, 200428

Although shell utilization by hermit crabs has been examined in other areas of the world (see Mantelatto and Garcia, 2000 for review), this type of work has been poorly con-ducted in this tropical region of southeastern Atlantic.

Material and Methods

Unoccupied gastropod shells and shells occupied by live gastropods and hermit crabs were col-lected monthly from January–December 2000, along the infralittoral rocky shores of East Beach, Anchieta Island, Ubatuba, São Paulo State, Brazil (23°33´S, 45°05´W). The characteristics of this rocky intertidal area have been described by Mantelatto and Garcia (2002). Pagurus brevidacty-lus hermit crabs and available shells (empty and with gastropods) were captured randomly over 870 m2, during the daytime by two SCUBA divers over a period of 40 min. Animals were frozen and transported to the laboratory for analysis. In the laboratory, hermit crabs were removed from their shells, weighed to the nearest 0.01 g (hermit crab weight, HW) and measured for shield length to the nearest 0.01 mm (shield length, SL). Measurements were made with a caliper (0.1 mm) or by drawing with the aid of a camera lucida.

Shells were identified according to Rios (1994) and confirmed by a specialist (Osmar Doman-eschi, IB/USP). Damaged shells that could not be identified were classified as “no identification” shells. Shell dry weight (SDW) and shell aperture width (SAW) were determined for all shells collected. Shell internal volume (SIV) was measured by the volume of fine sand (Ø = 0.25–0.105 mm3) required to fill the empty shell (Bertness, 1981b). Mollusc tissue was removed from the shell before measuring the internal volume.

To determine correlations between the dimensions of hermit crabs and occupied shells, first the normality of hermit crab size (shield length) data was checked with a Kolmogorov-Smirnoff test, then regression analyses were performed (Spearman test). Multiple regression tests were performed to predict the relations between variables of the hermit crabs and occupied shells when they were treated all together. The chi-square test (χ2) was used to compare the percentage oc-cupancy of shell species by hermit crabs and the availability of both empty shells and those with live gastropods. The median variables of the shell species were analyzed with a nonparametric ANOVA (on Ranks Test). The level of significance was 0.05 for both tests.

Results

A total of 3704 gastropod shells of 32 species was collected. Shells occupied by liv-ing gastropods (1943; 52.46%) and hermit crabs (1528; 41.25%) were more frequently collected than those found empty (233; 6.29%; Table 1). Of 1528 hermit crabs collected, 634 were males (41.49%), 697 were ovigerous females (47.61%), and 197 were non-ovig-erous females (2.90%). Males were significantly larger (mean SL ± SD = 1.93 ± 0.36 mm; P < 0.05) than ovigerous (mean SL = 1.74 ± 0.27 mm) and non-ovigerous (mean SL = 1.55 ± 0.28 mm) females.

The mean density of hermit crabs was 1.75 ind m−2, and of available shells was 2.49 shells m−2 (2.22 shells with living gastropods m−2; 0.27 empty shells m−2). Hermit crabs occupied the shells of 17 gastropod species, whose shell aperture width (SAW) ranged from 0.80–10.80 mm (Fig. 1). In the smallest size class (0.80–5.80 mm SAW), most shells were occupied by hermit crabs (40.96%), followed by live gastropods (34.38%). Only 0.87% of small shells were empty. The median aperture width, weight, and internal volume of empty and gastropod-inhabited shells were significantly larger (P < 0.05) than those occupied by hermit crabs, and the aperture width of the empty shells was larger than gastropod-occupied shells (ANOVA on Ranks: P < 0.01).

MANTELATTO AND MEIRELES: SHELL OCCUPATION BY PAGURUS BREVIDACTYLUS 29

Shells of the gastropod Cerithium atratum (Born, 1778) were the most available (χ2

= 124.55; df = 1; P < 0.01), followed by Pisania auritula (Link, 1807), Astraea olfersii (Philippi, 1844), and M. nodulosa, respectively (Table 1). Shells of three of these species (C. atratum, M. nodulosa, P. auritula) and Anachis lyrata (Sowerby, 1832), were the most occupied shells by P. brevidactylus, accounting for more than 93% of the total. Of the total occupied shells by P. brevidactylus, 40% were damaged, and 1% of these shells were so damaged that their identification was not possible.

There was a significant difference (χ2 test; df = 1) between shells used by hermit crabs and their relative abundance in the field. For example the occupancy rates of M. nodu-losa was significantly higher than its relative abundance (χ2 = 180.07; df = 1; P < 0.01);

Table 1. Total number of shells of gastropod species available in the field (with live gastropods and empty) and occupied by Pagurus brevidactylus, on Anchieta Island, Brazil.

Shell Species Live Gastropods

Empty Inhabited by crabs

Total

N % N % N % N %Anachis lyrata (Sowerby, 1832) 1 0.03 - - 29 0.78 30 0.81Astraea latispina (Philippi, 1844) 38 1.03 53 1.43 - - 91 2.46Astraea olfersii (Philippi, 1844) 168 4.54 93 2.51 3 0.08 264 7.13Astraea phoebia Röding, 1798 24 0.65 5 0.13 5 0.13 34 0.92Bulla striata Buguìere, 1792 1 0.03 - - - - 1 0.03Calliostoma bullisi Clench and Turner, 1960 9 0.24 11 0.30 - - 20 0.54Cerithium atratum (Born, 1778) 681 18.39 14 0.38 736 19.87 1,431 38.63Chicoreus tenuivaricosus (Dautzenberg, 1927) 3 0.08 - - - - 3 0.08Collumbela mercatoria (Linnaeus, 1758) 1 0.03 - - - - 1 0.03Coralliophila aberrans (C.B. Adams, 1850) 3 0.08 - - 9 0.24 12 0.32Costoanachis sertularium Orbigny, 1841 7 0.19 - - 3 0.08 10 0.27Cymatium parthenopeum (von Salis, 1793) 34 0.92 12 0.32 - - 46 1.24Cyprea zebra Linnaeus, 1758 1 0.03 2 0.05 - - 3 0.08Favartia cellulosa (Conrad, 1846) 21 0.57 - - - - 21 0.57Fusinus brasiliensis (Grabau, 1904) 8 0.22 1 0.03 - - 9 0.24Leucozonia nassa (Gmelin, 1791) 26 0.70 3 0.08 4 0.11 33 0.89Mitrella argus Orbigny, 1842 1 0.03 - - - - 1 0.03Modulus modulus (Linnaeus, 1758) 11 0.30 - - 14 0.38 25 0.67Morula nodulosa (C.B. Adams, 1845) 243 6.56 3 0.08 647 17.47 893 24.11Muricopsis necocheana (Pilsbry, 1900) - - - - 2 0.05 2 0.05Nassarius albus (Say, 1826) 2 0.05 - - 5 0.13 7 0.19Oliva reticularis Lamarck, 1810 - - 1 0.03 - - 1 0.03Olivancillaria urceus (Roding, 1798) - - 6 0.16 - - 6 0.16Pilsbryspira leucocyma (Dall, 1883) 2 0.05 - - 1 0.03 3 0.08Pisania auritula (Link, 1807) 543 14.66 4 0.11 17 0.46 564 15.23Pisania pusio (Linnaeus, 1758) 13 0.35 1 0.03 2 0.05 16 0.43Polinices lacteus (Guilding, 1833) - - 5 0.13 5 0.13 10 0.27Stramonita haemastoma (Linnaeus, 1767) 43 1.16 2 0.05 3 0.08 48 1.30Strombus pugilis Linnaeus, 1758 - - 4 0.11 1 0.03 5 0.13Tegula viridula (Gmelin, 1791) 56 1.51 12 0.32 4 0.11 72 1.94Tonna galea (Linnaeus, 1758) - - 1 0.03 - - 1 0.03Trachypollia turricula (von Maltzan, 1884) - - - - 1 0.03 1 0.03No identification 3 0.08 - - 37 1.01 40 1.08Total 1,943 52.46 233 6.29 1,528 41.25 3,704 100

BULLETIN OF MARINE SCIENCE, VOL. 75, NO. 1, 200430

Figure 2. Shell occupation as a function of hermit crab, Pagurus brevidactylus, shield length (SL).

Figure 1. Frequency distribution of the shell aperture width (SAW) for all shells collected (oc-cupied by Pagurus brevidactylus crabs and available), on Anchieta Island, Brazil.

MANTELATTO AND MEIRELES: SHELL OCCUPATION BY PAGURUS BREVIDACTYLUS 31

Figure 3. Regression between hermit crab, Pagurus brevidactylus, shield length (SL) and weight (HW), shell dry weight (SDW) and internal volume (SIV), for the individuals collected (P < 0.001).

Table 2. Regression analysis between the measurements of the crabs and top four most occupied shells (r

s = Spearman correlation coefficient; SL = shield length; HW = hermit crab weight; SAW

= shell aperture width; SIV = shell internal volume; SDW = shell dry weight; * = significant correlation, P < 0.05).

Species N Relation Linear equation

Y = aXb

rs

A. lyrata 5 SIV × SL SIV = 0.02SL2.16 0.90*29 SDW × SL SDW = 0.06SL3.53 0.78*5 SIV × HW SIV = 0.60HW0.67 0.94*

28 SDW × HW SDW = 14.04HW1.04 0.82*C. atratum 104 SIV × SL SIV = 0.01SL3.40 0.83*

638 SDW × SL SDW = 0.11SL2.83 0.71*103 SIV × HW SIV = 1.52HW0.92 0.83*725 SDW × HW SDW = 3.69HW0.69 0.74*

M. nodulosa 310 SIV × SL SIV = 0.01SL2.90 0.83*17 SDW × SL SDW = 0.18SL2.29 0.72*

308 SIV × HW SIV = 0.76HW0.74 0.81*636 SDW × HW SDW = 6.07HW0.74 0.71*

P. auritula 4 SIV × SL SIV = 0.001SL5.86 0.9217 SDW × SL SDW = 0.18SL2.29 0.72*4 SIV × HW SIV = 13.52HW2.05 0.90

17 SDW × HW SDW = 8.79HW0.84 0.84*

BULLETIN OF MARINE SCIENCE, VOL. 75, NO. 1, 200432

whereas the abundance rate of P. auritula was significantly higher than its occupancy rate (χ2 = 498.05; df = 1; P < 0.01). For C. atratum shells, the occupancy and the abun-dance rates were not significantly different (χ2 = 1.17; df = 1; P < 0.05).

Muricopsis necocheana (Pilbry, 1900) and Trachypollia turricula (von Maltzan, 1884) were only found occupied by hermit crabs, while Bulla striata Bruguiere, 1792, Chicoreus tenuivaricosus (Dautzenberg, 1927), Columbella mercatoria (Linnaeus, 1758), Favartia cellulose (Conrad, 1846), and Mitrella argus D’Orbigny, 1842 were only found inhabited by live gastropods, while Oliva reticularis Lamarck, 1810, Olivancil-laria urceus (Roding, 1798) and Tonna galea (Linnaeus, 1758) were only found empty (Table 1).

Hermit crab occupation of gastropod shells differed between the sexes. Cerithium atratum shells were occupied significantly more frequently by males than by ovigerous and non-ovigerous females (χ2 = 159.35 and χ2= 16.0, respectively; df = 1; P < 0.01). In contrast, M. nodulosa shells were occupied more frequently by ovigerous females (χ2 = 85.89; df = 1; P < 0.01).

Cerithium atratum, M. nodulosa, and A. lyrata shells were occupied mainly by hermit crabs of small (SL = 0.8–1.6 mm) to intermediate (SL = 1.6–2.8 mm) size classes. Pisa-nia auritula shells were occupied primarily by larger crabs of larger size classes (SL = 2.8–3.4 mm; Fig. 2).

The variables that best describe the association between hermit crabs and their shells were shield length (SL), hermit crab weight (HW), shell internal volume (SIV), and shell dry weight (SDW; Fig. 3). We examined the association between crabs and their shells for only the four most occupied shells (Table 2).

Discussion

With regard to hermit crab occupation, the gastropod shell diversity of Anchieta Island is high when compared to other studied areas (Ohmori et al., 1995; Mantelatto and Gar-cia, 2000). Available shells (with live gastropods and empty) represented 58.75% of the total shells collected, suggesting that the shell availability in the area is high (consistent with Mantelatto and Garcia, 2002). However, high shell availability does not necessarily imply that conditions are favorable for occupation, due to high damage and/or to a lim-ited size range (Martinelli and Mantelatto, 1999; Garcia and Mantelatto, 2000). Empty gastropod shells tend to be scarce in natural habitats occupied by hermit crabs, and therefore sub-optimal sized and damaged shells are frequently used (Lancaster, 1988). This low availability of empty shells (6.29% of total shells collected) might be related to several factors such as low gastropod mortality rates, quick occupation of empty shells by the high diversity and abundance of hermit species (nine in total – see Mantelatto and Garcia, 2002) in the studied area, switching of shells by hermit crabs in the infralittoral zone, and transport of shells to other areas by currents (Vance, 1972a).

As expected, P. brevidactylus mainly occupied the three most available gastropod shells in the area. Moreover, one of these species (C. atratum) was occupied by five of the nine hermit crab species that live at Anchieta Island (Mantelatto and Garcia, 2002). Gastropod shells are scarce in habitats occupied by hermit crabs, which results in the utilization of damaged shells or smaller shells than the size needed by the hermit crab (Vance, 1972b; Bach et al., 1976; Abrams, 1978). The niche overlap and consequent competitions for resources by the different hermit crab species is similar to that found elsewhere (Abrams, 1987; Manjón-Cabeza and Garcia-Raso, 1999; Mantelatto and Gar-

MANTELATTO AND MEIRELES: SHELL OCCUPATION BY PAGURUS BREVIDACTYLUS 33

cia, 2002) and contributes to the high occupancy of damaged shells (40% of total oc-cupied).

Although males and females (ovigerous and non-ovigerous) occupied mainly the same shell species, there were some differences between the sexes. Males were mostly found utilizing C. atratum shells, while females utilized M. nodulosa. Such difference in the shell utilization pattern according to hermit crab sexes has been found elsewhere (Gh-erardi, 1991; Mantelatto and Garcia, 2000; Benvenuto and Gherardi, 2001; Mantelatto and Dominciano, 2002). The size of the occupied shells was correlated with the size of male and female (ovigerous and non-ovigerous) hermit crabs. Females (ovigerous and non-ovigerous) of P. brevidactylus preferred proportionally heavier shells than males, probably related to enhanced protection against predators, such as brachyuran crabs, fishes, octopus, and other hermit crabs (pers. obs.).

Pagurus brevidactylus is a small species (0.91–3.32 mm SL), restricting its occupation patterns to small shells (0.80–10.80 mm SAW). The majority (96%) of shells collected (with gastropod and empty) in the study area were small (SAW ≤ 10.8 mm). However, only 1% of the total was empty. Thus, despite their abundance, small shells represent a limited resource to the hermit crabs. The majority of the empty shells were large, repre-senting a potential resource for occupancy by other larger species.

The shell occupation pattern generally paralleled shell availability, although there were some differences: Morula nodulosa and A. lyrata were occupied more frequently than shell availability would predict, while the frequency of occupation of P. auritula was lower than the shell availability. This last gastropod species reaches larger sizes than the other three common species, and was utilized by the large hermit crab specimens only, which might account for its low rate of occupancy by P. brevidactylus. Pisania auritula is in fact frequently occupied by two other sympatric hermit crab species (Paguristes tortugae Schmitt, 1933 and Paguristes erythrops Holthuis, 1959) in the study area (Man-telatto and Dominciano, 2002 and Mantelatto and Garcia, 2002, respectively).

There was a positive relationship between the size of the shells occupied and the size of the hermit crabs, showing that this species also occupies shells according to their suit-ability. Benvenuto and Gherardi (2001) demonstrated that hermit crabs have the capacity to select shells according to their dimensions; however, they found that this selectivity might be in agreement with patterns of shell availability.

Shell selection may be treated as a process that involves individual and sexual prefer-ences for different shell dimensions that best provide protection to the hermit crab (Gar-cia and Mantelatto, 2001). Particular shell parameters have been shown to be important to certain hermit crab species (Reese, 1962; Conover, 1978; Blackstone, 1985; Wilber, 1990). Lively (1988) conducted laboratory experiments and found that the shell inter-nal volume is more important than shell weight during shell selection because weight may vary due to epibionts, for example. Osorno et al. (1998) observed that hermit crabs preferred a higher ratio internal volume/shell weight during the shell selection. Beyond energy availability, the shell internal volume also may influence hermit crab growth (Fotheringham, 1976; Bertness, 1981b).

In summary, P. brevidactylus occupies C. atratum and M. nodulosa shells as a func-tion of their availability on Anchieta Island. Specific shell selection is related to hermit crab size and sex, and it is strongly based on the shell internal volume and dry weight (SDW). Such comparative studies of shell occupation by hermit crabs and gastropod shell availability enable the distinction between shell use and selectivity.

BULLETIN OF MARINE SCIENCE, VOL. 75, NO. 1, 200434

Acknowledgements

The authors are grateful to Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, Grants 98/07454-5; 99/11679-5) for financial support during field work to FLM and for Master Scholarship to ALM. We thank Secretaria do Meio Ambiente do Estado de São Paulo, IBAMA and Parque Estadual da Ilha Anchieta for permission (Proc. 42358/98) during sampling work. Special thanks are due to R. Biagi for help during field collection, laboratory analysis and valu-able comments on the manuscript and to O. Domaneschi (Department of Zoology – IB – Uni-versity of São Paulo), for assistance with gastropod identification. Thanks are due to anonymous refeerees for suggestions on earlier draft of the manuscript.

Literature Cited

Abrams, P. A. 1978. Shell selection and utilization in a terrestrial hermit crab, Coenobita compres-sus (H. Milne Edwards). Oecologia 34: 239–253.

___________. 1987. An analysis of competitive interactions between three hermit crabs species. Oecologia 72: 233–247.

Bach, C. B., B. A. Hazlett, and D. Rittschof. 1976. Effects of interspecific competition on the fit-ness of the hermit crab Clibanarius tricolor. Ecology 57: 579–586.

Benvenuto, C. and F. Gherardi. 2001. Population structure and shell use in the hermit crab, Clibanarius erythropus: a comparison between Mediterranean and Atlantic shores. J. Mar. Biol. Ass. U.K. 81: 77–84.

Blackstone, N. W. 1985. The effects of shell size and shape on growth and form in the hermit crab Pagurus longicarpus. Biol. Bull. 168: 75–90.

Bertness, M. D. 1981a. Pattern and plasticity in tropical hermit crab growth and reproduction. Am. Nat. 170: 754–773.

____________. 1981b. The influence of shell-type on hermit crab growth rate and clutch size. Crustaceana 40: 197–205.

Conover, M. 1978. The importance of various shell characteristics to the shell-selection behavior of the hermit crabs. J. Exp. Mar. Biol. Ecol. 32: 131–142.

Dowds, B. M. and R. W. Elwood. 1983. Shell wars: assessment strategies and the timing of deci-sions in hermit crab shell fights. Behaviour 85: 1–24.

Fotheringham, N. 1976. Population consequences of shell utilization by hermit crabs. Ecology 57: 570–578.

Garcia, R. B. and F. L. Mantelatto. 2000. Variability of shell occupation by intertidal and infralit-toral Calcinus tibicen (Anomura, Diogenidae) populations. Nauplius 8: 99–105.

__________ and _______________. 2001. Shell selection by the tropical hermit crab Calcinus tibicen (Herbst, 1791) (Anomura, Diogenidae) from southern Brazil. J. Exp. Mar. Biol. Ecol. 265: 1–14.

Gherardi, F. 1991. Relative growth, population structure, and shell utilization of the hermit crab Clibanarius erythropus in the Mediterranean. Oebalia 17: 181–196.

___________ and P. M. Cassidy. 1995. Life history patterns of Discorsopagurus schmitti, a hermit crab inhabiting polychaete tubes. Biol. Bull. 188: 68–77.

Hazlett, B. A. and W. Herrnkind. 1980. Orientation to shell events by the hermit crab Clibanarius antillensis. Anim. Behav. 35: 218–226.

Lancaster, I. 1988. Pagurus bernhardus (L.) An introduction to the natural history of hermit crabs. Field Studies 7: 189–238.

Lively, C. M. 1988. A graphical model for shell-species selection by hermit crabs. Ecology 69: 1233–1238.

Manjón-Cabeza, M. E. and J. E. García Raso. 1999. Shell utilization by the hermit crabs Diogenes pugilator (Roux, 1829), Paguristes eremita (Linnaeus, 1767) and Pagurus forbesii Bell, 1845 (Crustacea: Decapoda: Anomura), in a shallow-water community from southern Spain. Bull. Mar. Sci. 65: 391–405.

MANTELATTO AND MEIRELES: SHELL OCCUPATION BY PAGURUS BREVIDACTYLUS 35

Mantelatto, F. L. and M. M. Souza-Carey. 1998. Caranguejos anomuros (Crustacea, Decapoda) as-sociados a Schizoporella unicornis (Bryozoa, Gymnolaemata) em Ubatuba (SP), Brasil. Anais do IV Simpósio de Ecossistemas Brasileiros, Águas de Lindóia (SP), Brasil: Praia, Represa e Mata. ACIESP 2(104): 200–206.

______________ and R. B. Garcia. 1999. Reproductive potential of the hermit crab Calcinus tibi-cen (Anomura) from Ubatuba, São Paulo, Brazil. J. Crust. Biol. 19: 268–275.

______________ and __________. 2000. Shell utilization pattern of the hermit crab Calcinus tibicen (Diogenidae) from southern Brazil. J. Crust. Biol. 20: 460–467.

______________ and __________. 2002. Hermit crab fauna from the infralittoral of Anchieta Is-land (Ubatuba, Brazil). Pages 137–144 in E.E. Briones and F. Alvarez, eds. Modern approaches to the study of Crustacea research. Kluwer Academic, Plenum Publishers, Hingham.

______________ and L. C. C. Dominciano. 2002. Pattern of shell utilization by the hermit crab Paguristes tortugae (Diogenidae) from Anchieta Island, southern Brazil. Sci. Mar. 66: 265–272.

Markham, J. 1968. Notes on the growth patterns and shell utilization of the hermit crab Pagurus bernhardus (L.). Ophelia 5: 189–205.

Martinelli, J. M. and F. L. Mantelatto. 1999. Shell occupation by the hermit crab Loxopagurus loxochelis (Moreira, 1901) (Anomura: Diogenidae) from Ubatuba Bay, Brazil. Pages 719–731 in F.R. Schram and J.C. Vaupel Klein, eds. Crustaceans and the biodiversity crisis. Brill, Leiden, The Netherlands.

Ohmori, H., S. Wada, S. Goshima, and S. Nakao. 1995. Effects of body size and shell availability on the shell utilization pattern of the hermit crab Pagurus filholi (Anomura: Paguridae). Crust. Res. 24: 85–92.

Osorno, J. L., L. Fernandéz-Casillas, and C. Rodríguez-Juarez. 1998. Are hermit crabs looking for light and large shells? Evidence from natural and field induced shell exchanges. J. Exp. Mar. Biol. Ecol. 222: 163–173.

Raimondi, P. T. and C. M. Lively. 1986. Positive abundance and negative distribution effects of a gastropod on an intertidal hermit crab. Oecologia 69: 213–216.

Reese, E. S. 1962. Shell selection behaviour of hermit crabs. Anim. Behav. 10: 347–360.Rios, E. C. 1994. Seashells of Brazil. Rio Grande do Sul. Fundação cidade do Rio Grande, Insti-

tuto Acqua, Museu Oceanográfico de Rio Grande, Universidade de Rio Grande. 2a Ed. 368 p. + 113 pl.

Rodrigues, L. J., D. W. Dunham, and K. A. Coates. 2000. Shelter preferences in the endemic bermudian hermit crab Calcinus verrilli (Rathbun, 1901) (Decapoda, Anomura). Crustaceana 73: 737–750.

Vance, R. R. 1972a. Competition and mechanism of coexistence of three sympatric species of intertidal hermit crabs. Ecology, 53: 1062–1074.

__________. 1972b. The role of shell adequacy in behavioral interactions involving hermit crabs. Ecology 53: 1075–1083.

Wilber, T. P., Jr. 1990. Influence of size, species and damage on shell selection by the hermit crab Pagurus longicarpus. Mar. Biol. 104: 31–39.

Date Submitted: 15 August, 2002. Date Accepted: 1 December, 2003.

Addresses: (F.L.M., A.L.M) Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), Universidade de São Paulo (USP), Av. Bandeirantes 3900, CEP 14040-901, Ribeirão Preto, São Paulo, Brazil. Corresponding Author: (F.L.M.) E-mail: <flmantel@usp.br>.