Communication and mutual resource exchange in north Florida hermit crabs

The patterns of shell exchange in three species of hermit crabs which overlap in distribution and shell use were observed in the laboratory. Crabs showed no tendency to initiate more exchanges with conspecifics as compared with nonconspecific individuals and there were no specific size dominance effects. Lack of common communicatory patterns between Clibararius vittatus and Pagurus pollicaris was correlated with minimal actual exchange, while Pagurus impressus exchanged with both species and executed patterns in common with both. The pattern of shell exchanges and preferences indicated that, in some cases, both individuals may gain in interspecific exchanges.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46904/1/265_2004_Article_BF00569198.pd

Estrutura populacional de Petrolisthes armatus (Gibbes) (Decapoda, Anomura, Porcellanidae) da Ilha do Farol, Matinhos, Paraná, Brasil Population structure of Petrolisthes armatus (Gibbes) (Decapoda, Anomura, Porcellanidae) from Farol Isle, Matinhos, Paraná, Brazil

<abstract language="eng">Population structure of the porcelain crab Petrolisthes armatus (Gibbes, 1850) from the rocky shore of the Farol isle (25º51'S, 48º32'W) was carried out in the following aspects: annual fluctuation of the density, distribution of the developmental stages and sexes over year round, size composition and recruiting period of juveniles into the population. Monthly collections were made in the three sites of the midlittoral, from November/89 to April/91, with the aid of a trap. The air temperature ranged from 13ºC to 28ºC, that of the surface water from 16ºC lo 29ºC and the salinity of the surface water from 06.7‰ to 31.5‰. A total of 5.585 individuals of Petrolisthes armatus was collected, among which, 116 were in the megalopa stage, 1,579 juveniles, 830 immature males, 729 immature females, 1,161 mature males, 744 mature females and 426 ovigerous females. The population density ranged from 15.3 to 305.0 ind.m-2, with a peak in January. This density is the highest among the porcelain crab populations known from the literature. The species has continuous reproduction, but, there were two main cohorts in the year: summer one that was longer and more abundant and the winter one that was shorter and the less numerous