To what extent can freshwater crayfish recognise other crayfish?

Abstract

The ability for sophisticated and flexible recognition by vertebrates has been known for a very long time, probably because it features so strongly in human social behaviour and is therefore easily recognised in other species. Recent years have seen increased interest in the occurrence and properties of this response in non-vertebrates where it may not be so easily identified. Studies have now been undertaken on a wide range of organisms exemplified by the chapters of this review collection but our understanding of this phenomenon is still at an early stage and we can make few generalisations beyond its wide occurrence. In retrospect, its incidence should not be surprising. The advantages that it confers are apparent so that, all things being equal, it should be selected for. What characteristics of life history and interaction with con-specifics are likely to predict its presence and what factors predict the level of sophistication and flexibility? These questions remain to be answered but, based on what has already been discovered, we postulate here that it will evolve wherever there is a capacity for analysis of sensory signals that carry identifying information.