Low aggression in juvenile burrowing crayfish, Fallicambarus fodiens (Cottle, 1863) (Decapoda, Cambaridae)

[Informal observation suggested that Fallicambarus fodiens, which lives in close aggregations of mud burrows, exhibits less aggression than related epigean Cambarus spp. Interactions between size-matched, same sex pairs of F. fodiens were analysed in the laboratory. The analysis shows that these crayfish use behaviours similar to those used by Cambarus spp. in initiating agonistic interactions. However, approximately 84% of such interactions never proceed to the point of physical contact between the two opponents, whereas almost all comparable interactions in Cambarus spp. involve physical contact (fights). F. fodiens gather sufficient information for conflict resolution in a number of bouts of interaction comparable to that of other crayfish (differences not significant), but without physical interaction. Thus, these burrowing crayfish seem to have lower levels of aggression in comparison to more solitary, surface water crayfish species. This may be an adaptation for living in aggregations, where close co-habitation would be compromised by physical fighting and the subsequent extreme avoidance. Certaines observations ont suggere que Fallicambarus fodiens, qui habite dans des terriers vaseux agreges, est moins agressive que des especes epigees Cambarus proches. Les interactions entre paires de meme taille et meme sexe de F. fodiens ont ete analysees au laboratoire. Les analyses montrent que ces ecrevisses utilisent des comportements similaires a ceux de Cambarus spp. en debut d'interactions. Cependant, environ 84% de ces interactions n'arrivent pas jusqu'au contact physique entre les deux adversaires, alors que, au contraire, toutes les interactions comparables chez Cambarus spp. comprennent des contacts physiques (combats). F. fodiens rassemble assez d'information pour la resolution des conflits au cours d'un nombre d'assauts comparable au cas d'autres especes (difference non significative), mais sans contact physique. Donc, ces ecrevisses fouisseuses semblent presenter un niveau d'agressivite comparativement plus faible que celui d'ecrevisses plus solitaires, d'eaux de surface. Ce pourrait etre une adaptation leur permettant de vivre en groupes au niveau desquels la cohabitation serait compromise par des combats corporels et les comportements d'evitement qui en decouleraient. , Informal observation suggested that Fallicambarus fodiens, which lives in close aggregations of mud burrows, exhibits less aggression than related epigean Cambarus spp. Interactions between size-matched, same sex pairs of F. fodiens were analysed in the laboratory. The analysis shows that these crayfish use behaviours similar to those used by Cambarus spp. in initiating agonistic interactions. However, approximately 84% of such interactions never proceed to the point of physical contact between the two opponents, whereas almost all comparable interactions in Cambarus spp. involve physical contact (fights). F. fodiens gather sufficient information for conflict resolution in a number of bouts of interaction comparable to that of other crayfish (differences not significant), but without physical interaction. Thus, these burrowing crayfish seem to have lower levels of aggression in comparison to more solitary, surface water crayfish species. This may be an adaptation for living in aggregations, where close co-habitation would be compromised by physical fighting and the subsequent extreme avoidance. Certaines observations ont suggere que Fallicambarus fodiens, qui habite dans des terriers vaseux agreges, est moins agressive que des especes epigees Cambarus proches. Les interactions entre paires de meme taille et meme sexe de F. fodiens ont ete analysees au laboratoire. Les analyses montrent que ces ecrevisses utilisent des comportements similaires a ceux de Cambarus spp. en debut d'interactions. Cependant, environ 84% de ces interactions n'arrivent pas jusqu'au contact physique entre les deux adversaires, alors que, au contraire, toutes les interactions comparables chez Cambarus spp. comprennent des contacts physiques (combats). F. fodiens rassemble assez d'information pour la resolution des conflits au cours d'un nombre d'assauts comparable au cas d'autres especes (difference non significative), mais sans contact physique. Donc, ces ecrevisses fouisseuses semblent presenter un niveau d'agressivite comparativement plus faible que celui d'ecrevisses plus solitaires, d'eaux de surface. Ce pourrait etre une adaptation leur permettant de vivre en groupes au niveau desquels la cohabitation serait compromise par des combats corporels et les comportements d'evitement qui en decouleraient. ]