Host Selection, Host-Use Pattern and Competition in Dissodactylus Crinitichelis and Clypeasterophilus Stebbingi (Brachyura: Pinnotheridae)

Home , Clypeaster subdepressus, Dissodactylus, Dissodactylus mellitae, Irregularia

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/265377989

Host selection, host-use pattern and competition in Dissodactylus crinitichelis and Clypeasterophilus stebbingi (Brachyura: Pinnotheridae)

ARTICLE in SYMBIOSIS · AUGUST 2014 Impact Factor: 1.44 · DOI: 10.1007/s13199-014-0292-0

3 AUTHORS, INCLUDING:

José Eduardo Martinelli-Filho Federal University of Pará

8 PUBLICATIONS 28 CITATIONS

SEE PROFILE

All in-text references underlined in blue are linked to publications on ResearchGate, Available from: José Eduardo Martinelli-Filho letting you access and read them immediately. Retrieved on: 06 April 2016 Symbiosis DOI 10.1007/s13199-014-0292-0

Host selection, host-use pattern and competition in Dissodactylus crinitichelis and Clypeasterophilus stebbingi (Brachyura: Pinnotheridae)

José Eduardo Martinelli Filho & Ronan Brito dos Santos & Caio Cesar Ribeiro

Received: 28 April 2014 /Accepted: 15 August 2014 # Springer Science+Business Media Dordrecht 2014

Abstract The genera Dissodactylus and Clypeasterophilus from the echinoid to avoid competition, as observed during are commensal or parasitic crabs that live in association with the experiments. We suggest a species-specific association irregular sea urchins. Only a single pinnotherid species is between C. stebbingi and C. subdepressus,while expected to occur on a sand dollar; however, during field D. crinitichelis associated mainly with E. emarginata, but also observations, D. crinitichelis and Clypeasterophilus stebbingi with C. subdepressus. Both crabs may harm the echinoids by were found co-occurring on a single host (Clypeaster consuming their spines, but additional research is necessary to subdepressus). Laboratory experiments and in situ observa- determine whether this is a parasitic association. tions were conducted to explore mechanisms of host selection and use by C. stebbingi, as well as the possibility of compe- Keywords Symbiosis . Decapoda . Echinoidea . Sand dollar tition with D. crinitichelis. Analysis of 213 specimens of Encope emarginata and 33 C. subdepressus revealed a high frequency of infestation (90 %) by brachyurans. The number 1 Introduction of D. crinitichelis was positively correlated with the size of E. emarginata. During field observations and experiments, Echinoderms are exclusively marine invertebrates, have a D. crinitichelis was able to colonize both echinoids, while wide distribution, and are one of the most abundant and C. stebbingi was found mainly on C. subdepressus.Noexclu- ecologically important components of the benthic megafauna sion was reported between individuals of the same sex for (Fell and Pawson 1966). They may comprise more than 90 % both crab species. However, D. crinitichelis may be territorial, of the metazoan biomass in the deep sea (Carters et al. 2009), since a single male occurred when adult females were added clearly showing the great importance of these organisms in to the host. D. crinitichelis and C. stebbingi co-occurred on the deeper regions. These invertebrates have different ecological same individual of C. subdepressus on rare occasions during roles, ranging from algal grazers (most sea urchins), to deposit field observations. C. stebbingi may exclude D. crinitichelis feeders (holothurians, sand dollars), filter feeders (crinoids, ophiuroids) and high-level predators (sea stars). The class Echinoidea composed of sea urchins and the J. E. Martinelli Filho (*) “irregular” sand dollars and sea biscuits (the monophyletic Oceanography Faculty, Geosciences Institute, Federal University of Irregularia), plays an additional key ecological role: their Pará, Campus Universitário do Guamá, Belém, PA 66075-110, Brazil e-mail: [email protected] walking and burrowing activities disturb sediments and organic matter on the bottom, suspending them in the water J. E. Martinelli Filho column. These nutrients become available to other species and e-mail: [email protected] enhance primary production (Loher et al. 2004). Moreover, R. B. dos Santos echinoids are commonly used in toxicity tests and as indica- Biological Sciences Faculty, Federal University of Pará, Coronel José tors of environmental quality, because of their sensitivity to Porfírio, 2515, São Sebastião, 68372-040 Altamira, PA, Brazil heavy metals and organic micropollutants (Coteur et al. 2003; Ghirardini et al. 2005). C. C. Ribeiro Marine Biology Department, Biology Institute, Fluminense Federal Due to the relatively large size of echinoderms, members of University, Campus Valonguinho, 24020-140 Niterói, RJ, Brazil all classes are hosts for many symbionts. The Apicomplexa J.E. Martinelli Filho et al. are the most common protists parasitizing echinoderms primitivus and its hosts, which was concluded to be (Jangoux 1987), while a wide variety of metazoans are para- ectoparasitism with an asymmetric exploitation of two hosts. sites or symbionts. For instance, the Myzostomida are a highly A few studies on the interaction between D. crinitichelis specialized and exclusive annelid clade of echinoderm para- and its hosts have been published (Telford 1982; Reeves and sites (Eeckhaut and Jangoux 1993). Crustaceans are another Brooks 2001), but none is related to Encope emarginata,its example of common symbionts: 13 copepod families are main host on the Brazilian coast. No information about the exclusive symbionts (Boxshall and Halsey 2004), of which interaction between Clypeasterophilus stebbingi and four are obligatory parasites on sea urchins (Boxshall and Clypeaster subdepressus was found. Often, a simple survey Ohtsuka 2001). Many other taxa may be associated, although of the occurrence and distribution of species is performed, but not exclusively, with echinoderm hosts, increasing the already includes no observations on the relationship between hosts high diversity of associated organisms. and symbionts or the host-use pattern (e.g., Martins and Many echinoids are important as hosts for a diverse and D’Incao 1996). abundant fauna of other invertebrates, mainly hydrozoans, Therefore, this study explored ecological aspects in- polychaete worms, gastropods, bivalves, bryozoans, and por- cluding the host selectivity, host-use pattern and relation- celain and pinnotherid crabs (Bell and Stancyk 1983; Baeza ship between the symbionts and their hosts. The possibil- and Thiel 2000;GeorgeandBoone2003; Campos et al. 2009; ity of competition between individuals of the two crab David et al. 2009). The associated fauna displays a wide range species co-occurring on a single host was also investigat- of ecological relationships with its hosts, from obligatory ed, and the influence of intra- and interspecific competi- parasites (Matsuda et al. 2013) to facultative commensals tion on host-selection was tested. Preliminary results on (Baeza and Thiel 2003). The frequency and abundance of the diet and behavior of D. crinitichelis and C. stebbingi such symbionts are highly variable, with occurrences from are also provided from in situ observations and laboratory less than 5 % to more than 90 %, and from a single to a few experiments. hundred specimens in a single host (e.g., Ory et al. 2013). The most common crustaceans associated with echinoids are the anomuran and brachyuran crabs, and their ecological 2Materialsandmethods associations are diverse. The brachyuran Holothuriophilus tomentosus is probably an amensalist on irregular sea urchins Aspects of the ecological relationship between the pinnotherid (Wirtz et al. 2009). Baeza and Thiel (2000)suggestedastrong crabs Dissodactylus crinitichelis and Clypeasterophilus commensalism between the porcellanid Liopetrolisthes mitra stebbingi and their respective hosts Encope emarginata and and the sea urchin Tetrapygus niger, and the pinnotherid Clypeaster subdepressus were studied at Ubatuba, a munici- Dissodactylus primitivus is a known ectoparasite hosted by pality on the southeastern coast of Brazil, during austral Meoma ventricosa and Plagiobrissus grandis (De Bruyn et al. summer (January 20 to February 1) and winter (July 17 to 2011). August 3), 2011. Two relatively unimpacted beaches, located Other associations between pinnotherid crabs from the in Flamengo Bay near the research station of the Oceano- genera Dissodactylus and Clypeasterophilus and several spe- graphic Institute of the University of São Paulo, were chosen cies of echinoids have been reported. Four species of Mellita for sampling and field observations (Fig. 1). Flamengo Beach are common hosts for D. mellitae (Telford 1982;Bell1984; is about 400 m long (23° 29′48″ S, 45° 06′36″ W) and George and Boone 2003); while species of Leodia, Mellita, Lamberto Beach is about 200 m long (23° 30′42″ S, 45° 06′ Meoma, Encope and Clypeaster are hosts for D. crinitichelis 30″ W). (Telford 1982; Werding and Sanchez 1989;Reevesand Brooks 2001; Queiroz et al. 2011). Clypeaster subdepressus 2.1 Population estimates and relationship between host size is the only known host for C. stebbingi (Werding and Sanchez and number of symbionts 1989;MartinsandD’Incao 1996), and C. europacificus and C. speciosus are hosts for Clypeasterophilus usufructus (Cam- The populations of the sand dollar Encope emarginata and pos et al. 2009). its associate D. crinitichelis were estimated at Lamberto The costs and benefits of symbiosis are not always clear, and Beach, by means of free or scuba diving. Echinoids were fluctuate along a continuum that is influenced by environmen- counted, and their width (as defined by Borzone 1992) tal and biological factors (Leung and Poulin 2008). Although measured in situ with a plastic ruler at depths between 1.5 several associations between pinnotherid crabs and their hosts and 4 m, within a polygon of approximately 4,000 m2 (the have been reported, the nature of these interactions remains entire length of the beach and part of the adjacent rocky unknown or incompletely described for most species. A rare shore). The crabs associated with 145 sand dollars were exception is the detailed analysis by De Bruyn et al.(2009, counted, during free diving. When possible (only during 2010) of the interaction between the crab Dissodactylus scuba diving), the crabs were also sexed and the Host selection and competition in pinnotherid crabs

Fig. 1 Southeastern coast of Brazil and the Municipality of Ubatuba. The enlargement shows part of Flamengo Bay, which encloses Lamberto and Flamengo beaches developmental stage (juvenile x adult) was determined 2.2 Collection and acclimation of organisms with aid of a hand magnifier and a ruler (for an additional 68 sand dollars). Individuals with carapace width larger Individuals of E. emarginata and C. subdepressus and their than 3 mm were considered adults (Fumis et al. 2006). respective symbionts were collected at Lamberto (for Two methods were applied to estimate the density of E. emarginata) and Flamengo Beach (for C. subdepressus). E. emarginata: the capture-mark-recapture and the transect During a dive, sand dollars were placed individually in method. For the first technique, a total of 50 and 100 Ziploc® plastic bags, which were slowly inserted into the echinoids were marked with small plastic clamps (placed substratum to prevent the symbionts from abandoning their between a lunula and the outer margin of the skeleton) hosts. The crabs found on each host were removed and indi- during the first and second assessment respectively. Recap- vidually placed in 50 ml Falcon tubes filled with seawater, ture was done 24 and 48 h after the initial marking, the immediately after the dive. marked and unmarked echinoids were counted, and the In the laboratory, sand dollars were acclimated in a density (org. m−2) was calculated by the Lincoln-Petersen temperature-controlled chamber at 21 °C, similar to the sub- method (Begon 1979). surface water temperature during collection. The echinoids The transect technique was applied by counting all sand were acclimated in 20 L plastic trays with sand from the dollars within 40 m2 rectangular areas (2×20 m, n =6). Each collection site, aquarium air pumps and sterilized (UV) fil- area was randomly placed inside the same polygon where the tered seawater, which was changed daily. Salinity was be- capture-mark-recapture sampling was performed. tween 34 and 36, and the dissolved-oxygen content was D. crinitichelis density (org. m−2) was estimated by in situ monitored. A maximum of five crabs, all from the same analysis of 213 specimens of E. emarginata. Themeannum- species, were placed in each 500 ml beaker to avoid possibly ber of crabs per host was multiplied by the estimates of the aggressive behavior, and were acclimated in the same condi- host’s density obtained by both the methods tested. The rela- tions described for the echinoids. All experiments were con- tionship between the size of C. subdepressus and the number ducted using healthy, active crabs after 24 h of acclimation. of its symbiont C. stebbingi was also determined on Flamengo Beach, by analyzing 33 sand dollars. Data normality was 2.3 Host-selection and competition experiments verified by the Shapiro-Wilk test. The Spearman correlation index was used to evaluate the relationship between the var- Host selection and competition experiments were performed iables, using Sigma-Plot 11 (Systat Software, 2008). using trays divided in the middle by a plastic net. Openings J.E. Martinelli Filho et al. that allowed the crabs to pass, but prevented direct contact manually attached to C. subdepressus, while C. stebbingi between the echinoids, were cut into the net at the sand-water crabs were randomly released on the sand. interface. For the host-selection experiments, a single sand A total of four crabs were used in each replicate for the dollar of each species was placed alternately on opposite sides experiments designed to test the existence of interspecific of the tray (to avoid placing a single species at the same end in competition. The number and sex of crabs attached to each every trial), and four crabs from the same species and similar sand dollar was observed at intervals of 1.5 h, totaling 9 to 12 carapace length were randomly placed on the sand (Fig. 2). observations for each of the experiments. For the host- For the first set of experiments, only individuals of selection experiments, a colonization index was calculated, D. crinitichelis were added to the trays; while individuals of by dividing the mean number of crabs per host during an C. stebbingi were provided for the second set. A third set of observation, by the total number of crabs placed in the trays experiments was conducted with C. stebbingi, but only one (%). The difference between the indexes was verified by the host was placed in each tray: six replicates containing a single Mann–Whitney or the Kruskal-Wallis test, followed by E. emarginata and another six with a single C. subdepressus. Student-Newman-Keuls for multiple comparisons. For the Four crabs were placed in each replicate for all three experi- host selection experiments, the binomial Z test was used to mental settings, and the number of individuals associated with compare the final position of the crabs with a random distri- the echinoids was counted at intervals of 1.5 h. bution, using each observation period as a replicate. Other experiments were conducted to evaluate the possi- Crabs were inspected on the sand in the bottom of the trays bility of intraspecific competition, aggression and territoriality during all the experiments. Six or seven replicates were con- between males and females of both species of crabs. Two ducted for each type of experiment, but those which contained D. crinitichelis adult males of similar size were placed man- one or more dead crabs during the observation period were ually on a single C. subdepressus in each tray. The same discarded. Some crabs went missing or died during the exper- experiment was conducted with a pair of non-ovigerous adult iments. When one or more crabs were missing, the replicate females. These experiments were also applied to was excluded, and therefore some experiments had fewer than D. crinitichelis, by attaching the crabs to E. emarginata.An- 6replicates. other experiment was conducted, with a total of four adult D. crinitichelis, two of each sex, manually placed on a single 2.4 Food selection tests E. emarginata, in order to observe the interaction and possible competition between males and females. Individuals of C. stebbingi were acclimated in multiwell plates Experiments to evaluate the existence of interspecific com- (Corning®); each animal was placed in a cavity containing petition between the two species of symbiont crabs were also 12 mL of filtered and sterilized seawater during a 24-h star- performed. In the first experiment, C. stebbingi was manually vation period. After starvation, spines removed from the echi- placed on C. subdepressus, while individuals of noids were provided in the cavities (n=9 cavities for each D. crinitichelis were randomly added to the sand in the bottom sand-dollar species). The crabs were incubated for 24 h and of the tray. For the second experiment, D. crinitichelis were the plates were photographed. Each well was inspected for the presence of spines and fecal pellets.

3Results

3.1 Relationship between host size and number of symbionts

The echinoid E. emarginata frequently hosted individuals of D. crinitichelis. In this study, unidentified bivalves, gastropods, a polychaete and a juvenile portunid crab were also reported on the sand dollars. Besides D. crinitichelis,only the bivalves were common symbionts, observed on 46.5 % of the echinoids. Fig. 2 Schematic drawing of the experimental tray for the host-selection The number of crabs (D. crinitichelis) showed a positive and competition experiments. The tray is divided in the middle by a and significant correlation with the host’ssizefor plastic net, allowing the crabs to pass through, but retaining the echinoids. ρ The crabs are enlarged for schematic purposes. Left: Encope emarginata; E. emarginata ( =0.19, p<0.01; Fig. 3a). The central axis right: Clypeaster subdepressus diameter of E. emarginata ranged from 6.1 to 13.2 cm (11.1± Host selection and competition in pinnotherid crabs

Fig. 3 The relationship between the host size (cm) and number of (n=213). b: absence of correlation between Clypeaster subdepressus size symbionts. a: positive and significant correlation between Encope and the number of Clypeasterophilus stebbingi (n=33) emarginata size and the number of associated Dissodactylus crinitichelis

1.3 cm) and the number of crabs was between 1 and 9 (2.1± Lamberto Beach was calculated by multiplying the estimates 1.5). Crabs were absent on only 13 % of the 213 sand dollars. of E. emarginata density (0.9 and 1.2 org.m−2) and the mean Scuba diving allowed determination of the sex of crabs number of crabs per host (2.14). The crab population at this associated with E. emarginata (n=68). Juveniles were more beach was estimated at between 7,704 and 10,236 individuals abundant than adults (110 of 171 individuals; p<0.001) and associated with the sand dollars. were more frequent on the echinoids (82 %) than males (44 %) or females (37 %). Only 33 adult males and 28 females were 3.3 Host-selection experiments counted, resulting in a sex ratio close to 1:1. Adults were observed on 67.6 % of the sand dollars, but were commonly During the host-selection experiments designed for – accompanied by juveniles (50 % of the echinoids). Male D. crinitichelis, the crabs were infrequently found on female pairs were observed on 13 % of the sand dollars; the C. subdepressus; the colonization index was between 5 and occurrence of more than one adult of the same sex was rare 25 % (11±9 %) when the crabs were present on the sand (3 % for males and 4 % for females). dollars. In contrast, at least one crab was associated with No correlation was observed between the diameter of E. emarginata during most of the observations, with an index ρ − C. subdepressus and the number of C. stebbingi ( = 0.154, p of 20–58 % (39±13 %; Fig. 4a). A similar pattern was =0.39; Fig. 3b). The central axis diameter for C. subdepressus observed for C. stebbingi and its host C. subdepressus:during was between 14.2 and 17.5 cm (15.5±0.9 cm) and the number most of the observations, crabs were associated with this sand of crabs per host was between 1 and 4 (1.7±1.1). No crabs were dollar or hidden in the sand. C. stebbingi rarely occurred on found on 4 of the 33 sand dollars analyzed. During the field E. emarginata (colonization index of 4±4 %; Fig. 4b). The observations, C. stebbingi was never observed on E. emarginata; crabs did not show a random distribution during the experi- however, D. crinitichelis was found in association with ments (p<0.001; binomial z test) and the difference between C. subdepressus on 2 of 33 echinoids. the colonization indexes (E. emarginata x C. stebbingi)was significant (p<0.001) for both crab species, suggesting a 3.2 Population densities for Encope emarginata and Dissodactylus crinitichelis at Lamberto Beach Table 1 Estimate of Encope emarginata density at Lamberto Beach (org.m−2), by the capture-mark-recapture technique. A total of 50 and Two methods were used to estimate the density of the sand 100 echinoids were marked during the first and second estimates respectively. The values are provided for the two different observers and for 24 dollar Encope emarginata at Lamberto Beach: the capture- and 48 h after the beginning of the experiment mark-recapture technique resulted in a density of 0.9±0.6 −2 −2 org.m−2 (Table 1), while the transects led to higher estimates Estimate Observer org.m –24 h org.m –48 h Mean and S.D. (1.2±1 org.m−2, Table 2). Only two assessments were done 1 A 0.4 0.5 0.9±0.5 for the capture-mark-recapture method. However, the estimate B 0.4 0.8 is included here because it resulted in a slightly lower density 2A1.91.4 than that obtained with the transect method, with a larger B1.3- number of replicates. The density of D. crinitichelis at J.E. Martinelli Filho et al.

Table 2 Estimate of Encope emarginata density at Lamberto Beach (org.m−2), by the transect method. A total of six 2x20 m (40 m2)transects at different depths (1.5–3.6 m) were sampled

Transect E. emarginata counted Mean depth (m) org. m−2

19 1.50.2 2 17 1.8 0.4 3 54 1.8 1.4 4 86 2.5 2.1 5 111 2.6 2.8 6 10 3.6 0.3

preference of D. crinitichelis for E. emarginata and of C. stebbingi for C. subdepressus. Fig. 5 Host-selection experiments for the crab Clypeasterophilus stebbingi. For these experiments, a single host was provided in each Another set of experiments was conducted for C. stebbingi, aquarium (n=6 for Clypeaster subdepressus and for Encope emarginata). where the symbionts were exposed to a single host in different Sand dollars were inspected at intervals of 1.5 h. Bars indicate the replicates. When only E. emarginata was provided, C. stebbingi standard deviation was rarely observed on the echinoid (colonization index be- tween0and8%),butburrowedinthesand.Incontrast,these crabs were commonly observed attached to C. subdepressus presence and absence of crabs (p<0.001), the difference be- (Fig. 5). The crabs showed a clear preference for tween the occurrence of one or two crabs was not significant C. subdepressus, as indicated by the binomial test (p<0.001). (p=0.173 for males and p=0.258 for females). A similar situation was observed for C. stebbingi,although the occurrence of two individuals of the same sex, associated 3.4 Intraspecific competition experiments with C. subdepressus, was more frequent than for D. crinitichelis on its respective host. C. stebbingi very rarely Apparently, there was no competition resulting in exclusion of failed to associate with its host (Fig. 7), a distinct difference individuals, for either males or females of D. crinitichelis.At between C. stebbingi and D. crinitichelis. A difference be- first, only two male crabs and a single E. emarginata were tween the numbers of individuals associated with the sand added (Fig. 6a), and during a second setting, two female crabs dollars was detected only for females (p<0.001, Kruskal- and a single host were provided (Fig. 6b). After the initial Wallis test and p<0.005, Student-Newman-Keuls). periods of observation, one or two individuals were frequently Another set of experiments was conducted for associated with the host and the rate of absence of brachyurans D. crinitichelis, where two individuals of each sex were decreased (Fig. 6). Despite the difference between the randomly placed in the same tray with a single E. emarginata

Fig. 4 Experiments on host selection between the sand dollars Dissodactylus crinitichelis and b:forClypeasterophilus stebbingi.Sand Clypeaster subdepressus and Encope emarginata for each of the crab dollars were inspected at intervals of 1.5 h (n=6) species. a: colonization index with the standard deviation for Host selection and competition in pinnotherid crabs

Fig. 6 Number of crabs (Dissodactylus crinitichelis) of the same sex associated with Encope emarginata. a: two males added; b: two females added. A single sand dollar was provided for each replicate (n=7 for each sex). Echinoids were inspected at intervals of 1.5 h as host. A single male generally occurred on the sand dollar, For the first set of experiments, D. crinitichelis was never and the two males were rarely observed together on the host. observed in association with C. subdepressus, whereas all The observation of a single female was the dominant pattern individuals of C. stebbingi were always present. This situation (p<0.001), although females were also observed alone or in occurred in all observations performed for this experiment (9 pairs on the same host (Fig. 8). These experiments indicate a periods of observation, n=3). For the second set of experi- possible competition and territoriality for the male crabs, in ments, D. crinitichelis gradually abandoned C. subdepressus, the presence of females on the echinoid, since the occurrence while C. stebbingi was found more frequently in association of a single male was more frequent than two males, or even the with its host (Fig. 9). absence of crabs (p<0.001, Kruskal-Wallis and p<0.05, Student-Newman-Keuls test). 3.6 Clypeasterophilus stebbingi food-selection tests 3.5 Interspecific competition experiments After 24 h when the crabs were allowed access to the spines of One C. subdepressus was provided as host for the two experi- the sand dollars, each well from the experimental plates was ments designed to evaluate the interspecific competition be- inspected. The crabs consumed spines from C. subdepressus, tween the two crab species. C. stebbingi was manually placed since only a few fragments of spines and several fecal pellets on the sand dollar, while D. crinitichelis was randomly released were observed in the wells where the spines of on the sand. A second and similar experiment was conducted, in C. subdepressus were added. However, the spines remained which C. stebbingi was randomly released on the sand, while on the bottom of the well and no fecal pellets were detected for D. crinitichelis was placed on the echinoid (Fig. 9). those replicates where E. emarginata spines were provided,

Fig. 7 Number of crabs (Clypeasterophilus stebbingi) of the same sex associated with the host Clypeaster subdepressus. a: two males added; b:two females added. A single sand dollar was provided for each replicate (n=6 for each sex). Echinoids were inspected at intervals of 1.5 h J.E. Martinelli Filho et al.

Fig. 8 Number of males and females of Dissodactylus crinitichelis on Encope emarginata. A single host plus two male and two female crabs were placed in each tray (n=6). Two males were rarely observed on the same host, in the presence of females. Left columns: number of males on the echinoid at each observation; right columns: number of females

suggesting that C. stebbingi fed only on the spines of its host association with C. subdepressus,whileD. crinitichelis is able C. subdepressus. to exploit different echinoid taxa. At least 7 species are hosts for D. crinitichelis (Table 3). In this study, E. emarginata was the main host for D. crinitichelis, but the crab was also observed on C. subdepressus. 4 Discussion The occurrence of more than one host is a common situation in Dissodactylus and Clypeasterophilus species, which Members of both crab genera Dissodactylus and may asymmetrically exploit different hosts (De Bruyn et al. Clypeasterophilus have been reported as associated with sev- 2010). The selection of two host species by D. crinitichelis, eral species of irregular sea urchins (Table 3). These crusta- and only a single host by C. stebbingi is very similar to the ceans are rarely observed on other invertebrates such as aster- condition described by Reeves and Brooks (2001)for oids (Martins and D’Incao 1996), or on different substrata D. crinitichelis and C. rugatus,respectively. such as Halodule meadows or sand (Melo 2008). This distribution itself constitutes evidence of a strict association be- 4.1 Density estimates and ecological implications tween these symbionts and the echinoids, as noted by several authors. The sand dollars E. emarginata and C. subdepressus are Published reports and the present field and experimental common in shallow waters on the north coast of São Paulo observations show that C. stebbingi has a species-specific state. Another sand dollar, Mellita quinquiesperforata, the

Fig. 9 Number of crabs (a: Clypeasterophilus stebbingi; b: Dissodactylus crinitichelis) associated with Clypeaster subdepressus for each observation period. At the beginning of the experiment, D. crinitichelis was manually placed on the sand dollar, while C. stebbingi was placed at a random location on the sand. A total of four crabs of each species were added to the tray (n=4) Host selection and competition in pinnotherid crabs

Table 3 List of hosts for the genera Clypeasterophilus and Dissodactylus, Pohle and Marques (1995); 18: Martins and D’Incao (1996); 19: Marques reported in the literature after 1900. 1: Rathbun (1901); 2: Glassell (1935); and Pohle (1996); 20: Reeves and Brooks (2001); 21: George and Boone 3: Clark (1940); 4: Rioja (1944); 5: Costa (1967); 6: Williams et al. (1968); (2003); 22: Fumis et al.(2006); 23: Melo (2008); 24: Campos et al.(2009); 7: Gray et al. (1968); 8: Telford (1978a); 9: Telford (1978b); 10: Telford 25: Wirtz et al.(2009); 27: De Bruyn et al.(2009); 28: De Bruyn et al. (1982); 11: Bell and Stancyk (1983); 12: Bell (1984); 13: Griffith (1987); (2010); 29: De Bruyn et al.(2011) 14: Bell (1988); 15: Werding and Sanchez (1989); 16: Pohle (1994); 17:

Crab species Reported hosts References

C. rugatus Clypeaster rosaceus, Encope michellini 10, 20 C. stebbingi C. subdepressus 13, 15, 18, 19, 23, here C. usufructus C. europacificus, C. speciosus 24 C. juvenilis C. subdepressus, Meoma ventricosa 13 D. crinitichelis C. rosaceus, C. subdepressus, E. emarginata, E. michellini, 5, 8, 9, 10, 13, 15, 18, Leodia sexiesperforata, Mellita quinquiesperforata, 20, 22, 25, 28, here Mellita sp., M. ventricosa D. glasselli E. micropora californica, E. wetmorei, Mellita grantii, 4, 17, 24 M. longifissa, M. kanakoffi D. latus C. subdepressus, Leodia sexiesperforata, E. michellini 13 D. lockingtoni E. grandis, E. micropora californica, Encope spp., Mellita 2, 13, 16, 17, 23, 24, grantii, M. longifissa, M. kanakoffi D. mellitae C. subdepressus, E. michellini, Leodia sexiesperforata, 1, 3, 6, 7, 10, 11, 12, Mellita isometra, M. quinquiesperforata 13, 14, 17, 21 D. nitidus E. grandis, E. micropora californica, Encope spp., 13, 24 M. longifissa D. primitivus Meoma ventricosa, Plagiobrissus grandis 8, 9, 10, 13, 26, 27, 29 D. xanthusi C. subdepressus, E. grandis, E. micropora californica, 13, 16, 24 E. michellini, Encope spp., Leodia sexiesperforata, Mellitella stokesii, Mellita longifissa

irregular sea urchins Cassidulus mitis and Plagiobrissus low, since the crabs may exchange hosts (different individuals grandis, and the sea urchins Lytechinus variegatus, or even species) and migrate from the echinoids to the open Echinometra lucunter and Arbacia lixula are also present in substratum, as observed in the experiments here and in other the region (Netto et al. 2005;Briteset al. 2011). Some of species of the genus (e.g., De Bruyn et al. 2010). This study these echinoids can occur in high densities, and conse- did not account for the crabs burrowed in the sand; but on the quently their symbionts also. Density estimates were per- other hand, D. crinitichelis is rarely collected in the sediment, formed only at Lamberto Beach, for E. emarginata and its where they are exposed to higher predation pressure (Reeves crab host D. crinitichelis. Data on the density of and Brooks 2001). The relatively large population of E. emarginata and its symbionts are sparse. Despite the D. crinitichelis estimated here, in contrast to its low reproduc- use of two methods and a low number of replicates, the tive effort (Telford 1978a, b), is an important clue that the values found here (Tables 1 and 2)aresimilartothose association with E. emarginata is beneficial for the symbionts, published by Arriguetti and Penchaszadeh (2010) off Mar probably by reducing crab mortality. del Plata, Argentina. The capture-mark-recapture method was tested here, but a 4.2 Host size implications few individuals were captured 24 and 48 h after marking, so the results may be biased and higher than expected. The An increase in the number of symbionts on larger hosts is method was then replaced by the transect approach; neverthe- expected for those symbionts that do not show territoriality or less, both methods resulted in similar values for E. emarginata host-resource monopolization (Baeza and Thiel 2003). Here, density. It is believed that the estimates described here are near the relationship between host size and number of symbionts to the natural abundance, since echinoid distribution is patchy was positive and significant for D. crinitichelis on and populations may reach high densities in tropical waters E. emarginata, as predicted by the models of Baeza and Thiel (Dias 2008). (2003 and 2007). The size of the D. crinitichelis population was estimated The smallest individuals of both species of sand dollars from the density of sand dollars, and resulted in a large were not analyzed. These missing data would probably raise number of symbionts. This estimate is probably somewhat the correlation coefficient, since smaller individuals should J.E. Martinelli Filho et al. carry fewer symbionts and with less frequency (Baeza and 4.4 Food selection, diet, and consequences Thiel 2000; Baeza and Stotz 2001). It is also possible that a minimum threshold size is required for the crabs to associate The members of the genera Dissodactylus and with the echinoids (Baeza and Stotz 2001), but this hypothesis Clypeasterophilus are frequently defined as commensal crabs. remains to be tested for E. emarginata and C. subdepressus. Although many species feed on spines and tissues from their The lack of correlation between the size of C. subdepressus echinoid hosts (Telford 1982), few researchers have evaluated and the number of C. stebbingi may therefore be explainable the consequences for the hosts. Here, the feeding behavior of by the low number of observations for this sand dollar and the D. crinitichelis was not studied, but the spines of Leodia limited range of sizes analyzed. sexiesperforata were the dominant item in the diet of a pop- Similarly, some studies have shown that the larger the host, ulation from Barbados (Telford 1982). the more numerous were the adult crabs (Baeza et al. 2001;De On the northeastern coast of Brazil, D. crinitichelis proba- Bruyn et al. 2009), probably reflecting a carrying capacity of bly feeds mainly on spines and tissue from E. emarginata. the echinoid hosts. If the host’sspinesareacommonitemin Nevertheless, these crabs may be able to survive in the ab- the symbiont’s diet, as observed for D. crinitichelis, sence of echinoid hosts, since juveniles were fed with Artemia D. mellitae, D. primitivus, C. juvenilis and C. rugatus (Telford nauplii, and kept in containers with shell fragments and a 1982; Griffith 1987;DeBruynet al. 2009), it would be skeleton of E. emarginata for a study of growth rates (Fumis reasonable for symbionts to select larger hosts. A larger stock et al. 2006). An experiment, offering spines and tegument of food resources would explain the positive correlation found from different echinoid species, is suggested to evaluate food between the numbers of E. emarginata and the size of preferences and the crab’s ability to survive in the absence of D. crinitichelis. E. emarginata. Nevertheless, the probability of infestation was not affected C. stebbingi showed a clear preference for spines of by host size, since individuals of all sizes of both species were C. subdepressus, and did not feed on E. emarginata spines. found without symbionts (Fig. 3). A similar pattern was This result also suggests that C. stebbingi has only one echi- observed by De Bruyn et al.(2009). However, the size range noid host. Little information, if any, is available about the of the hosts inspected here was relatively limited, and smaller ecology and association of C. stebbingi. The experiments hosts may display lower frequencies of associated symbionts, conducted here suggest that this crab is possibly an ectopara- as described by Baeza and Stotz (2001). site feeding on tissues and spines, since scars were observed on some of the hosts (personal observations). 4.3 Frequency of infestation Spine morphology and microstructure are diversified in echinoid species, differing in characteristics such as the A high frequency of infestation was noted for both weight-volume relationship, porosity, and dimensions E. emarginata and C. stebbingi, with nearly 90 % of the (Telford 1982;Davidet al. 2009). It is possible that individuals bearing crabs. High levels seem to be common C. stebbingi chelipeds are adapted to sever the spines of for Dissodactylus species (Gray et al. 1968; Telford C. subdepressus, but are unable to remove them from species 1978a, b;Bell1988;DeBruynet al. 2009 and 2010). such as E. emarginata. Additional information on food selec- Other decapods such as porcellanid crabs are frequent tion may be obtained from an analysis of spine structure and symbionts as well: Allopetrolisthes spinifrons was present cheliped anatomy, as investigated by Telford (1982). Interest- on 58 and 77 % of its main anemone host species (Baeza ingly, those species of Dissodactylus that have been analyzed and Stotz 2001), while Leopetrolisthes mitra occurred on in detail were concluded to be ectoparasites. D. primitivus is 77.5 % of the sea urchin host Tetrapygus niger (Baeza and known to be parasitic, because it causes tissue damage and Thiel 2000). An exception is the study conducted by reduction of the reproductive effort of its hosts (Telford 1982; Telford (1978a, b), where the frequency of D. crinitichelis De Bruyn et al. 2009), and D. mellitae causes lower egg on Leodia sexiesperforata was lower, between 30 and production rates in Mellita isometra (George and Boone 61 %). Other studies, which were not designed to estimate 2003). crab densities and thus resulted in accidental capture of the The large number of crab symbionts found here may symbionts, generally resulted in lower frequencies as well negatively affect the echinoid hosts. The effects of the (see Bell 1988). symbionts on the sand dollars were not evaluated, but The high frequency of D. crinitichelis on E. emarginata,in areas cleaned of spines were observed on some of the contrast to its low rate of occurrence on C. subdepressus, is echinoids harboring the crabs. Both symbiont species important evidence that the former echinoid is the main host studied here are probably parasitic, although additional for this crab. Curiously, megalopa stages of D. crinitichelis research is needed to evaluate the load caused by these and C. stebbingi were not observed on either echinoid, raising symbionts on their hosts and to classify the association as uncertainties about the life cycle of these crabs. a parasitism. Experimental approaches such as the analysis Host selection and competition in pinnotherid crabs of correlation between host size and injured areas, move- References ment patterns and sexual parameters (the ratio between gonad and body volume, as studied by De Bruyn et al. Arriguetti F, Penchaszadeh PE (2010) Macrobenthos-sediment relation- 2009) of parasitized versus healthy echinoids are ships in a sandy bottom community off Mar del Plata, Argentina. J suggested. Mar Biol Assoc U K 90(5):933–939 Baeza JA, Stotz WB (2001) Host-use pattern and host-selection during ontogeny of the commensal crab Allopetrolisthes spinifrons (H. Milne Edwards, 1837) (Decapoda: Anomura: Porcellanidae). J Nat 4.5 Symbiont behavior Hist 35:341–355 Baeza JA, Thiel M (2000) Host use pattern and life history of The results from the experiments and field observations sug- Liopetrolisthes mitra, a crab associate of the black sea urchin Tetrapygus niger. J Mar Biol Assoc UK 80:639–645 gest that D. crinitichelis adult males may exclude other male Baeza JA, Thiel M (2003) Predicting territorial behavior in symbiotic competitors, but allow the presence of females and juveniles, crabs using host characteristics: a comparative study and proposal of since more than one adult male was observed in only 3 % of a model. Mar Biol 142:93–100 the analyzed sand dollars and the presence of a single male Baeza JA, Thiel M (2007) The mating system of symbiotic crustaceans. A conceptual model based on Optimality and Ecological Constraints among females and juveniles was also common (39.7 % of the (Chapter 12). In evolutionary ecology of social and sexual systems: observations). It is suggested that adult males show aggressive crustaceans as model organisms (Duffy JE and Thiel M, eds). behavior, and that a female-centered polygyny mating system Oxford University Press, pp 250–267 proposed by Baeza and Thiel (2007) occurs in this species. Baeza JA, Stotz W, Thiel M (2001) Life history of Allopetrolisthes spinifrons, a crab associate of the sea anemone Phymactis clematis. Male territoriality and possible host monopolization by J Mar Biol Assoc UK 81:69–76 D. crinitichelis should be carefully analyzed in future Begon M (1979) Investigating animal abundance: capture-recapture for research. biologists. Edward Arnold, London This is the first report of two co-occurring pinnotherid Bell JL (1984) Changing residence: dynamics of the symbiotic relationship between Dissodactylus mellitae Rathbun (Pinnotheridae) and species on a single echinoid host. Although this co- Mellita quinquiesperforata (Leske) (Echinodermata). J Exp Mar occurrence was rather infrequent in the field (2 of 33 Biol Ecol 82:101–115 C. subdepressus analyzed), the experimental results also dem- Bell JL (1988) Distribution and abundance of Dissodactylus mellitae onstrated that D. crinitichelis may colonize C. subdepressus. Rathbun (Pinnotheridae) on Mellitae quinquiesperforata (Leske) (Echinodermata). J Exp Mar Biol Ecol 117:93–114 On the other hand, C. stebbingi is possibly territorial and may Bell JL, Stancyk SE (1983) Population dynamics and reproduction of dislodge its competitor D. crinitichelis from the sand dollar, Dissodactylus mellitae (Brachyura: Pinnotheridae) on its sand dollar explaining the low frequency of co-occurrences (Fig. 9). The host Mellita quinquiesperforata (Echinodermata). Mar Ecol Prog – possible territoriality of C. stebbingi, the relatively low abun- Ser 13:141 149 Borzone CA (1992) Spatial distribution and growth of Mellita dance of C. subdepressus, and a smaller number of symbionts quinquiesperforata (Leske, 1778) on a sandy beach of southern per host are characteristics of the host-defense polygyny mat- Brazil. Nerítica 7:87–100 ing system (Baeza and Thiel 2007). Boxshall GA, Halsey SH (2004) An introduction to copepod diversity. C. subdepressus is less abundant than E. emarginata, and is Ray Society, London, p 966 Boxshall GA, Ohtsuka S (2001) Two new families of copepods also an uncommon host for D. crinitichelis. This leads to the (Copepoda: Siphonostomatoida) parasitic on echinoderms. J conclusion that D. crinitichelis will exploit C. subdepressus as Crustac Biol 21:96–105 an additional host, if this echinoid is not already colonized by Brites AD, Hadel VF, Tiago CG (2011) Crinoidea, Asteroidea, its main symbiont C. stebbingi, or if E. emarginata is not Echinoidea, Holoturoidea. In Amaral ACZ, Nalin SAH, eds. Biodiversidade e ecossistemas bentônicos marinhos do litoral available. Norte de São Paulo, Sudeste do Brasil. Campinas, pp 273–279 Physical interaction between the crabs was never actually Campos E, Campos AR, Leon-González JA (2009) Diversity and eco- observed, and a higher frequency of observations or a video logical remarks of ectocommensal sand ectoparasites (Annelida, system should be used to detect such behavior. The mating Crustacea, Mollusca) of echinoids (Echinoidea: Mellitidae) in the Sea of Cortez, Mexico. Parasitol Res 105:479–487 systems suggested here must be properly tested, as well as the Carters JE, Maynou F, Fanelli E, Romano C, Mamouridis V, Papiol V consequences of intraspecific and interspecific competition (2009) The distribution of megabenthic, invertebrate epifauna in the for host-selection and host-use pattern and the evolution of Balearic Basin (western Mediterranean) between 400 and 2300 m: behavior in D. crinitichelis and C. stebbingi. environmental gradients influencing assemblages composition and biomass trends. J Sea Res 61:244–257 Clark HL (1940) Eastern pacific expeditions of the New York zoological society. XXI. Notes on the echinoderms from the west coast of Central America. Zoologica 25:331–352 Acknowledgments We are grateful to the technicians from the Costa HR (1967) As espécies brasileiras da família Pinnotheridae (Crustacea Clarimundo de Jesus Research Base in the Municipality of Ubatuba and Reptantia) com descrição de uma nova espécie (Fabia sebastianensis). to Drs. Michel Mahiques and Rubens Lopes from the Oceanographic Oceanogr Stud Fed Univ Pernambuco 9(11):255–264 Institute of the University of São Paulo for the facilities provided. The Coteur G, Gosselin P, Wantier P, Chambost-Manciet Y, Danis B, Pernet P, help of Allyson Nardelli was essential during the field work. Warnau M, Dubois P (2003) Echinoderms as bioindicators, biassays, J.E. Martinelli Filho et al.

and impact assessment tools of sediment-associated metal and PCBs and a comparison with other species within the Dissodactylus com- in the North Area. Arch Environ Contam Toxicol 45:190–202 plex. Bull Mar Sci 58(1):165–185 David B, Stock SR, De Carlo F, Hétérier V, De Ridder C (2009) Martins ST, D’Incao F (1996) Os Pinnotheridae de Santa Catarina e Rio Microstructures of Antarctic cidaroid spines: diversity of shapes Grande do Sul, Brasil (Decapoda, Brachyura). Revta Bras Zool and ectosymbiont attachments. Mar Biol 156:1559–1572 13(1):1–26 De Bruyn C, Rigaud T, David B, De Ridder C (2009) Symbiosis between Matsuda H, Hamano T, Nagasawa K (2013) Growth and reproductive the pea crab Dissodactylus primitivus and its echinoid host Meoma cycle of Hypermastus tokunagai (Caenogastropoda: Eulimidae), an ventricosa: potential consequences for the crab mating system. Mar ectoparasite of the sand dollar Scaphechinus mirabilis Ecol Prog Ser 375:173–183 (Clypeasteroida: Scutellidae) in the Seto Inland Sea, Japan. J Mar De Bruyn C, David B, De Ridder C, Rigaud T (2010) Asymmetric Biol Assoc UK 93(4):1041–1051 exploitation of two echinoid host species by a parasitic pea crab Melo GAS (2008) The Brachyura (Decapoda) of ilha grande bay, Rio de and its consequences for the parasitic life cycle. Mar Ecol Prog Ser Janeiro, Brazil. Nauplius 16(1):1–22 398:183–191 Netto LF, Hadel VF, Tiago GC (2005) Echinodermata from São Sebastião De Bruyn C, De Ridder C, Rigaud T, David B (2011) Chemical host channel (São Paulo, Brazil). Rev Biol Trop 53:207–218 detection and differential attraction in a parasitic pea crab infecting Ory NC, Dudgeon TM (2013) Host-use patterns and factors influencing two echinoids. J Exp Mar Biol Ecol 397:173–178 the choice between anemone and urchin hosts by caridean shrimp. J Dias ICCM (2008) Biologia populacional de Mellita quinquiesperforata Exp Mar Biol 449:85–92 Leske (1778) (ECHINODERMATA: CLYPEASTEROIDA: Pohle GW (1994) Dissodactylus xantusi and Dissodactylus lockingtoni MELLITIDAE) na praia da Taíba, Ceará, Brasil. Master’s thesis. (Decapoda: Brachyura: Pinnotheridae): larval development of two Universidade Federal do Ceará, Fortaleza, Brazil, 145p. (in sympatric Pacific species. Can J Zool 72:575–590 Portuguese) Pohle G, Marques F (1995) First zoea of Dissodactylus glasselli Eeckhaut I, Jangoux M (1993) Life cycle and mode of infestation of Rioja and new range and host records for species of Myzostoma cirriferum (Annelida), a symbiotic myxostomid of the Dissodactylus (Brachyura: Pinnotheridae), with a discussion comatulid crinoid Antedon bifida (Echinodermata). Dis Aquat Org of host-symbiont biogeography. Proc Biol Soc Wash 108(5): 15:207–217 247–253 Fell HB, Pawson DL (1966) General biology of echinoderms. In: Queiroz V, Sales L, Neves E, Johnson R (2011) Dissodactylus Boolootian RA (ed) Physiology of echinodermata. Interscience, crinitichelis Moreira, 1901 and Leodia sexiesperforata (Leske, New York, pp 1–48 1778): first record of this symbiosis in Brazil. Nauplius 19:63–70 Fumis PB, Fransozo A, Bertini G, Braga AA, Pie MR (2006) Growth rate Rathbun MJ (1901) The Brachyura and Macrura of Porto Rico. Bull. US of the crab Dissodactylus crinitichelis Moreira, 1901 (Crustacea: Fish Comm Fish Bull 20:1–127 Decapoda: Pinnotheroidea) under laboratory conditions. Proc Biol Reeves MN, Brooks WR (2001) Host selection, chemical detection, and Soc Wash 119(3):395–403 protection of the symbiotic pinnotherid crabs Dissodactylus George SB, Boone S (2003) The ectosymbiont crab Dissodactylus crinitichelis and Clypeasterophilus rugatus associated with echino- mellitae—sand dollar Mellita isometra relationship. J Exp Mar derms. Symbiosis 30:239–256 Biol Ecol 294:235–255 Rioja E (1944) Estudios carcinológicos XVI. Observaciónes sobre Ghirardini AV, Novelli AA, Tagliapietra D (2005) Sediment toxicity algunas especies de cangrejos del genero Dissodactylus Smith assessment in the Lagoon of Venice (Italy) using Paracentrotus (Braquiros, Pinnoteridos) de las costas Mexicanas del Pacifico. lividus (Echinodermata: Echinoidea) fertilization and embryo bioas- Ann Inst Biol Mex 15:147–160 says. Environ Int 31:1065–1077 Telford M (1978a) Distribution of two species of Dissodactylus Glassell SA (1935) New or little known crabs from the Pacific coast of (Brachyura: Pinnotheridae) among their echinoid host populations northern Mexico. Trans San Diego Soc Nat Hist 8:91–106 in Barbados. Bull Mar Sci 28(4):651–658 Gray IE, McCloskey RM, Weihe SC (1968) The commensal crab Telford M (1978b) Post-larval growth in two species of Dissodactylus Dissodactylus mellitae and its reaction to sand dollar host-factor. J (Brachyura: Pinnotheridae). Bull Mar Sci 28(4):645–650 Elisha Mitchell Sci Soc 84:472–481 Telford M (1982) Echinoderm spine structure, feeding and host relation- Griffith H (1987) Taxonomy of the genus Dissodactylus (Crustacea: ships of four species of Dissodactylus (Brachyura: Pinnotheridae). Brachyura: Pinnotheridae) with descriptions of three new species. Bull Mar Sci 32(2):584–594 Bull Mar Sci 40(3):387–422 Werding B, Sanchez H (1989) Pinnotherid crabs of the genus Jangoux M (1987) Diseases of Echinodermata. I. Agents microorganisms Dissodactylus Smith, 1870, associated with irregular sea urchins at and protistans. Dis Aquat Org 2:147–162 the Caribbean coast of Colombia (Crustacea: Decapoda: Leung TLF, Poulin R (2008) Parasitism, commensalism, and mutualism: Pinnotheridae). Zool Meded 63(4):35–42 exploring the many shades of symbioses. Mid Life 58(2):107–115 Williams AB, McCloskey IR, Gray IE (1968) New records of brachyuran Loher AM, Thrush SF, Gibbs MM (2004) Bioturbators enhance ecosys- decapod crustaceans from the continental shelf off North Carolina, tem function through complex biogeochemical interactions. Nature U.S.A. Crustaceana 15:41–66 431:1092–1095 Wirtz P, De Melo G, De Grave S (2009) Symbioses of decapod Marques F, Pohle G (1996) Complete larval development of crustaceans along the coast of Espírito Santo, Brazil. Mar Clypeasterophilus stebbingi (Decapoda: Brachyura: Pinnotheridae) Biodivers Rec 2:1–9