[show abstract][hide abstract] ABSTRACT: Schejter, L. and Mantelatto, F.L. 2011. Shelter association between the hermit crab Sympagurus dimorphus and the zoanthid Epizoanthus paguricola in the southwestern Atlantic Ocean. —Acta Zoologica (Stockholm) 92: 141–149.The available literature on zoanthid–hermit crab associations deals only with records of this phenomenon, providing no detailed information. We describe, for the first time, the shell-like colonies of Epizoanthus paguricola associated with the hermit crab Sympagurus dimorphus from benthic samples taken in the Argentine Sea, between 85 and 131 m depth, and provide information about morphometric relationships between the hermits and the zoanthids. In total, 260 specimens (137 males and 123 females) of S. dimorphus were collected, 240 (92.3%) of which were living in symbiosis with E. paguricola. The remaining 20 (7.7%) were living inside gastropod shells. As the initial structure of the pseudoshell, 12 different gastropod species were found (all were almost totally covered with colonies of E. paguricola). The hermit crab lives in the spiral cavity inside the soft colony, which seemed to be slightly different depending on the initial gastropod. Aperture pseudoshell morphology did not seem to be related to the sex of the hermit crab host, although males showed larger apertures for a given colony size. This fact is probably related to a larger size of male’s cheliped (sexual dimorphic character) used like a gastropod operculum and that may serve as a template for the growing of the aperture pseudoshell edge. The number of epizoanthid polyps per colony increased in relation to the weight of the colony and to the size of the hermit crab. A process of selection of the initial shell was evident, because species of Naticidae were not the most common gastropods in this benthic community, but were those most used by hermit crabs (>60%). The puzzling association between hermit crab, shell and zoanthid presumably occurs during the hermit juvenile phase, when the crab occupies a small shell, and a zoanthid larva settles on it. Given the close relationship between S. dimorphus and E. paguricola found in this region, we support the idea that due to the low availability of adequate gastropod shells for hermit life cycle, this association allows the establishment and the continuity of the hermit crab population in the studied area.
[show abstract][hide abstract] ABSTRACT: An unidentified species of hermit crab from the Maldives was photographed using a plastic box as shelter instead of a natural shell. This could be a result of increased pollution and shell collection disrupting the natural processes in coral reefs.
[show abstract][hide abstract] ABSTRACT: Hermit crabs of the species Pagurus criniticornis (Dana, 1852) parasitized by the poorly known colonial rhizocephalan Peltogasterella socialis (Müller, 1863), were collected in the infralittoral rocky/sandy area of Anchieta Island (São Paulo), Brazil. We report the presence and pattern of occurrence of this rhizocephalan in the P. criniticornis population. The hermit crabs were obtained monthly during 1999 by two people using SCUBA methods. A total of 992 hermit crabs were captured and examined for rhizocephalans. The studied population showed non-normal size distribution and only 2.11% of the sample specimens carried externae of P. socialis. The parasite occurrence was seasonal and varied with host size. Some signs of feminization were observed on P. criniticornis pleopods (elongation of the endopod and reduction of the exopod of pleopods for males and reduction in the size of endopods for females). This is the first report on this parasite/host relationship for this South American host species. This is the first record of P. socialis (Müller, 1863) subsequent to the species' description, and possible occurrence of the parasite on hermit crabs in the Bahamas is also reported.
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