104 - We thank Dr. Raymond B. Manning for confirming Acknowledgements. the identification of the specimens and for reviewing the manuscript; Drs. E. C. Raney and R. L. Wigley for their comments on the manuscript; R. D. Brodeur for technical assistance; and T. C. Ellis for drawing the figure. REFERENCES R. P., 1894. Report on the Crustacea of the order Stomatopoda collected by the steamer BIGELOW, Albatross between 1885 and 1891, and on other specimens in the U.S. National Museum. Proc. U.S. natn. Mus., 17: 489-550, pls. 20-22, text-figs. 1-28. R. B., 1962. Seven new species of stomatopod crustaceansfrom the northwestern Atlantic. MANNING, Proc. biol. Soc. Washington, 75: 215-222. 1967. Preliminary account of a new genus and a new family of Stomatopoda. Crustaceana, -, 13 (2): 238-239. 1969. Stomatopod Crustacea of the western Atlantic. Stud. trop. Oceanogr. Miami, 8: -, i-viii + 1-380. 1974. Marine flora and fauna of the northeastern United States. Crustacea: Stomatopoda. -, NOAA tech. Rep. NMFS Circ.-387. SMITH,S. I., 1881. Preliminary notice of the Crustacea dredged, in 64 to 325 fathoms, off the south coast of New England, by the U.S. Fish Commissionin 1880. Proc. U.S. natn. Mus., 3: 413-452. OF PREDATION PRESSURE ON THE MUTUALISTIC THE HERMIT CRAB, PAGURUS POLLICARIS BETWEEN CALLIACTIS TRICOLOR SAY, 1817, AND THE SEA ANEMONE, EFFECTS INTERACTION (LESUEUR, 1817) BY CATHERINE E. BACH Division of Biological Sciences,University of Michigan, Ann Arbor, Michigan 48109, U.S.A. and WILLIAM F. HERRNKIND Department of Biological Science, Florida State University, Tallahassee, Florida 32306, U.S.A. Introduction. - Mutualistic interactions between organisms are widespread in the marine environment (see reviews by Dales, 1966, and Fricke, 1975). There has been much speculation as to the benefits to each organism, but there is a marked lack of data supporting these speculations. A commonly hypothesized benefit of a mutualistic interaction is protection from predation (e.g. anemone-fish, Mariscal, 1970; scallop-sponge, Bloom, 1975; fish-shrimp, Fricke, 1975; and zoanthidIn the case of it should be possible mutualisms, West, sponge, 1976). obligate to determine the degree to which the mutualistic interaction provides predator protection by removing the mutualistic partner and observing a decline in survivor. ship of the other organism. However, if the mutualism is facultative, one could 105 between the frequency of the mutualism and the also look for a relationship would be especially true if the formation of the This of intensity predation. association occurred by active behaviors of the interacting organisms. If one mutualistic partner is benefiting from predator protection, a greater frequency of the mutualistic interaction is predicted in areas with greater predation pressure. This study tests this hypothesis for a mutualism between a hermit crab, Pagurus pollicari.r Say, and a sea anemone, Calliacti.r tricolor (Lesue.ur) . It has been suggested for such associations that the sea anemone protects the hermit crab from predation (Ross, 1967; 1971). In some associations both the crab and the anemone initiate the interaction (Ross & Sutton, 1961). Laboratory experiments document that P. pol/¡caris is indeed protected from predators such as the oxystomatid crab, and the octopus, Octopus joubini Adam, by having Calappa f lammea (Herbst), the anemone on its shell (McLean & Mariscal, 1973). In addition, another hermit crab species, Dardanu.r arrOJor (Herbst), increases its behavior of acquiring anemones after octopus predators are introduced in laboratory conditions after a long absence (Balasch & Mengual, 1974). It has been suggested that C. tricolor benefits from the interaction by having a hard substrate on which to attach, allowing anemones to inhabit regions without suitable substrates for attachment, and by the interception of food particles while crabs feed (Ross, 1967). Some species of anemones even show preference for motile crabs over other substrates (Ross, 1974) and some species of hermit crabs actually feed their sea anemones (Fox, 1965). whether predictions arising from the results of In this study, we determined of McLean's and Mariscal's are upheld in the field, i.e. laboratory experiments is there a greater frequency of P. pollicarz.r carrying anemones in areas of greater predation pressure? Materials and methods. - Surveys were conducted during June, 1978, at five shallow-water sites near the Florida State University Marine Laboratory, Sopchoppy, Florida (A: Bay Mouth Bar, B and C: Dog Island Shoals, D and E: Turkey Point Shoal). At each site, all individuals of P. pollicaris found while searching for were collected and the following data were four person-hours approximately recorded for each crab: (1) species of gastropod shell occupied, (2) presence or absence of recent aperture damage to the gastropod shell, and (3) presence or absence of anemone ( s ) on the gastropod shell. Relative intensity of predation pressure was measured by the frequency of gastropod shells inhabited by hermit crabs which showed evidence of recent damage by predators. The box crab, Calap pa f lammea, a common predator on P. pollicari.r, diurnally lives buried in the sand (thus making density estimates very difficult), but leaves characteristic damage marks on shells (Shoup, 1968) by breaking them open with a modified cheliped. Since measures of current, not past predation pressure, were desired, only recent shell damage attributable to C. f lammea was recorded (i.e., no epibiota on broken portion of shell). Results. - There is a significant positive linear relationship between predation pressure, as measured by the percentage of recently damaged shells, and the 106 frequency of hermit crabs carrying anemones (fig. 1). The particular gastropod shell species present could affect the probability of a shell becoming damaged or the probability of a hermit crab inhabiting that shell carrying an anemone. We compared the frequency of shells with anemones to the overall frequency of the various shell species and found no effect of shell species on the probability of = 8.8, = 9, df p> .25 ) . Similarly, finding an anemone on a shell (chi-squared the distribution of damaged shells also is not different from that predicted by chance alone, based on the total number of shells of each species (chi-squared = = 13.2, df 9, p > . i o ) . Thus, the distribution of shell species in the five sites cannot explain the differences in the frequencies of damage or anemones between sites. Discussion. - It appears that the higher the intensity of predation by shelldamaging predators at a particular site, the higher the frequency of the mutualistic interaction between P. pollicariJ and C. tricolor. This relationship is not simply a function of different shell assemblages at the five sites, nor is it likely to be a function of different availabilities of anemones, since all sites were similar in depth, substrate, and salinity patterns. In fact, the difference in anemone frequency is much greater between different locations on the same sand bars than between certain sites on different sand bars; e.g., site C on the offshore Dog Island Shoal and site E on the inshore Turkey Point Shoal. Although the number of sites is not as large as would be desirable, the large amount of variance explained by the linear regression is indicative of a biologically realistic relationship. Obviously a more direct way to test whether the presence of an anemone on a Fig. 1. Relationship between predation pressure and percentage of Pagttrus pollicari.r Say carrying anemones. Predation pressure is measured by the percentage of crabs in shells recently damaged by Calappa flammea (Herbst). The equation for the regression line is y = .84 x + 2.61 (r2 = .83, p<.05). Sample sizes of the collections at the five sites were: A (N = 75), B (16), C (29), D (80), and E (27). Standard errors of estimates of the percentagesare indicated. 107 shell protects its hermit crab inhabitant, would be to analyze the relationship between predation pressure and anemone frequency for individual crabs (i.e., do those crabs which are carrying anemone(s) have a lower frequency of damaged this kind of is because hermit analysis shells?). However, clearly inappropriate crabs are continually changing shells and also can transfer their anemones to their new shells (Hazlett, 1972). It must be pointed out that frequency of shell damage is only a relative estimate of predation pressure. In addition to the characteristic damage to shell apertures, C. f lammea may also break spires and render shells unfit for habitation by hermit crabs. Other species may also damage some shells while removing epibiota. Finally, other hermit crab predators, such as Octopus joubini, which do not damage shells, may contribute to the phenomenon of increased incidence of anemones. Despite these limitations, our data support the hypothesis that the anemone, C. tricolor, may indeed provide protection for P. pollicaris. The predictions derived from laboratory experiments seem to be supported in the field. However, a more complete test of this hypothesis would involve studying survivorship of marked crabs both with and without anemones and obtaining accurate density information on predators. - We thank the Florida State Acknowledgements. University Marine Laboratory and the Psychobiology Program for support of this research. Also we thank Brian Hazlett and William Lindberg for assistance in data collection, and Diane Deand David Wethey for Steven, Pat Dillon, Brian Hazlett, John Vandermeer, comments on the manuscript. LITERATURECITED 1974. The behavior of Dardanus arrosor in association with Calliactis J. & V. MENGUAL, BALASCH, parasitica in artificial habitat. Mar. Beh. Phys., 2: 251-260. BLOOM,S. A., 1975. The motile escape response of a sessile prey: sponge-scallopmutualism. Journ. exp. mar. Biol., 78: 311-328. DALES,R. P., 1966. Symbiosisin marine organisms. In: S. M. HENRY,ed., Symbiosis,1 (Academic Press, New York). Fox, H. M., 1965. Confirmation of old observations on the behavior of a hermit crab and its commensal sea anemone. Ann. Mag. nat. Hist., (13) 8: 173. FRICKE,H. W., 1975. The role of behavior in marine symbiotic animals. Soc. expl. Biol. Symp., 29: 581-594. HAZLETT,B. A., 1972. Ritualization in marine Crustacea. In: H. E. WINN & B. L. OLLA,eds., Behavior of Marine Animals, 1: 97-125. (Plenum Press, New York). 1973. Protection of a hermit crab by its symbiotic sea anemone MCLEAN,R. B. & R. N. MARISCAL, Calliactis tricolor. Experientia, 29: 128-130. R. N., 1970. The nature of the symbiosisbetween Indo-Pacific anemone fishes and sea MARISCAL, anemones.Mar. Biol., 6: 58-65. Ross, D. M., 1967. Behavioral and ecologicalrelationships between sea anemones and other invertebrates. Ann. Rev. Oceanogr. mar. Biol., 5: 291-316. 1971. Protection of hermit crabs (Dardanus spp.) from Octopus by commensalsea anemones -, (Calliactis spp.). Nature (London), 230: 401-402. 1974. Evolutionary aspects of associationsbetween crabs and sea anemones. In: W. B. VERN--, BERG,ed., Symbiosisin the Sea. (Univ. South Carolina Press, Columbia, South Carolina). Ross, D. M. & L. SUTTON,1961. The associationbetween the hermit crab Dardanus arrosor (Herbst) and the sea anemone Calliactis parasitica (Couch). Proc. roy. Soc. London, 155: 282-291. . 108 SHOUP,J. B., 1968. Shell opening by crabs of the genus Calappa. Science,New York, 160: 887-888. WEST,D. A., 1976. Aposematic coloration and mutualism in sponge-dwellingtropical zoanthids. In: G. O. MACKIE,ed., Coelenterate Ecology and Behavior: 443-452. (Plenum Press, New York). AN INDIAN OCEAN RECORD FOR SADAYDSHIA BABA (DECAPODA, ANOMURA) ACROPORAE BY NASIMA M. TIRMIZI Invertebrate Reference Museum, University of Karachi, Karachi, Pakistan The genus Sadayoshia Baba, 1969 of the family Galatheidae contains five species, all Indo-Pacific. Only one, S. edwardsi (Miers), was previously recorded from the Indian Ocean. Three male specimens, obtained by the International Indian Ocean a new Indian Ocean record for Sadayoshia Expedition (IIOE) 1963-1964, provide acropora.e Baba known only from the type locality: Ryukyu Islands (Baba, 1972: 43 ). The specimens at hand agree well with the holotype except in some details which are noted in the following account. Sadayoshia acroporae Baba, 1972 Sta. AB 29, Anton Bruun Cruise 1; 11°23'N 93°31'E, 80 m, 28 March 1963; 1 Sta. 363 P, Anton Bruun Cruise 7; 23°17'S 43°33'E, 1225 m, 6 August 1964 2 a a mutilated and therefore not included in the detailed study). (one badly Measurements (in mm; of the male from Sta. AB 29 and the least damaged male from Sta. 363 P, respectively). - Carapace length (including rostrum, but extreme tip broken), 10, 9; carapace breadth, 6, 5.5; length of cheliped, 20 (left), 19 (right), -, (broken in the second specimen but at least 12 mm long). The material will be deposited in the National Museum of Natural History, Smithsonian Institution, Washington, D.C. The rostrum and the supraorbital spines are without scales in the larger specimen from Sta. AB 29 (fig. 1); with a few scattered ones in the smaller specimen from Sta. 363 P (fig. 2). The outer orbital angle is rather acute. The carapace, excluding the rostrum, is either as long as or slightly longer than wide. A small additional stria (fig. 1, s) is present behind the second stria of the carapace, in the larger specimen. In the smaller specimen the number of striae m front of the cervical groove is reduced. There are only three striae behind the additional stria. Only one or two coarse setae are present on the dorsal surface of the carapace. In the larger specimen there is an additional marginal tooth on the right side, as illustrated. The third maxilliped has the inner terminal tooth of the ischium poorly devel-