crab {condvis}R Documentation

Brockmann's crab data


Abstract from original paper: Horseshoe crabs arrive on the beach in pairs and spawn in the high intertidal during the springtime, new and full moon high tides. Unattached males also come to the beach, crowd around the nesting couples and compete with attached males for fertilizations. Satellite males form large groups around some couples while ignoring others, resulting in a nonrandom distribution that cannot be explained by local environmental conditions or habitat selection. In experimental manipulations, pairs that had satellites regained them after they had been removed whereas pairs with no satellites continued nesting alone, which means that satellites were not simply accumulating around the pairs that had been on the beach the longest. Manipulations also revealed that satellites were not just copying the behaviour of other males. Based on the evidence from observations and experiments, the most likely explanation for the nonrandom distribution of satellite males among nesting pairs is that unattached males are preferentially attracted to some females over others. Females with many satellites were larger and in better condition, but did not lay more eggs, than females with few or no satellites.

satellites response variable; number of satellites around female crab
color color of crab
spine condition of spine
weight weight of crab
width width of carapace


173 observations on 5 variables.



Brockmann, H. (1996), "Satellite male groups in horseshoe crabs," Ethology, 102-1, pp. 1-21.



[Package condvis version 0.5-1 Index]