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The main goals of this investigation were to describe the community structure of anomuran and brachyuran crabs inhabiting reefs constituted by colonies of Schizoporella unicornis, and to provide a species importance ranking for this community. Collections were carried out on S. unicornis reefs at two-month intervals from May 2003 to May 2004, in the rocky sublittoral of the southeastern Brazilian coast. Relative abundance and occurrence were used to rank these species in the hierarchy importance. A total of 2,018 individuals were obtained, in 11 families, 22 genera and 31 species. Porcellanidae and Pilumnidae were the most abundant families, comprising respectively almost 60% and 15% of individuals sampled. The species ranking indicated four main groups A, B, C and D, with group A subdivided. Subgroup A1 contained 9 species, including the species of greatest ecological importance for community regarding abundance and occurrence. The great abundance of crabs associated with S. unicornis seems to be the result of its recognized importance during the crab developmental cycle, and as shelter and food for some Decapod species. These observations reveal the importance of conserving the areas occupied by these reef colonies, which appear to be an important environment for maintaining local biodiversity.Os principais objetivos deste estudo foram descrever a estrutura da comunidade de caranguejos anomuros e braquiúros que habitam recifes constituídos por colônias de Schizoporella unicornis, e fornecer uma ordenação das espécies mais importantes para esta comunidade. As coletas foram realizadas bimestralmente desde maio de 2003 até maio de 2004, no infralitoral rochoso da costa sudeste brasileira. A abundância e ocorrência relativas foram usadas para ordenar estas espécies em hierarquia de importância. Obteve-se um total de 2.018 indivíduos, distribuídos em 11 famílias, 22 gêneros e 31 espécies. Porcellanidae e Pilumnidae foram as famílias mais abundantes, compreendendo, respectivamente, cerca de 60% e 15% dos indivíduos amostrados. A ordenação das espécies indicou quatro grupos principais A, B, C e D, sendo o grupo A subdividido em dois. O subgrupo A1 contém 9 espécies, incluindo as espécies de maior importância ecológica para a comunidade, com relação à abundância e ocorrência. A grande abundância de caranguejos encontrados associados com S. unicornis é resultado de sua importância reconhecida durante o ciclo de desenvolvimento, e como abrigo e alimento para algumas espécies de decápodos. Estas observações revelam a importância de conservar as áreas ocupadas por essas colônias de briozoários, que parece ser um ambiente importante para a manutenção da biodiversidade local.

The main goals of this investigation were to describe the community structure of anomuran and brachyuran crabs inhabiting reefs constituted by colonies of Schizoporella unicornis, and to provide a species importance ranking for this community. Collections were carried out on S. unicornis reefs at two-month intervals from May 2003 to May 2004, in the rocky sublittoral of the southeastern Brazilian coast. Relative abundance and occurrence were used to rank these species in the hierarchy importance. A total of 2,018 individuals were obtained, in 11 families, 22 genera and 31 species. Porcellanidae and Pilumnidae were the most abundant families, comprising respectively almost 60% and 15% of individuals sampled. The species ranking indicated four main groups A, B, C and D, with group A subdivided. Subgroup A1 contained 9 species, including the species of greatest ecological importance for community regarding abundance and occurrence. The great abundance of crabs associated with S. unicornis seems to be the result of its recognized importance during the crab developmental cycle, and as shelter and food for some Decapod species. These observations reveal the importance of conserving the areas occupied by these reef colonies, which appear to be an important environment for maintaining local biodiversity.