In some crayfish populations dominance status is important in shelter and food acquisition, as well as reproductive success. An organism’s status within a population is determined over time by agonistic interactions with population members. Physical characteristics such as body size, chelae size and number can affect the results of these interactions and the overall probability that an organism will have a dominant or subordinate status.

Several species of crayfish, including Procambarus clarkii, have also been shown to establish dominance relationships. Crayfish behavior towards an individual is influenced by the outcome of past conflicts with that individual, and possibly the other individual's status, which leads to shorter interactions between organisms. It was originally thought that these subsequent behaviors depended upon learned individual recognition of dominant members by subordinate members . Copp (1986), using results from Thorpe and Ammerman (1978), suggests that it is not recognition of individuals that is occurring, but recognition of aggressive state. Since Thorpe and Ammerman (1978) did not quantify aggression or agonistic interactions, the only conclusion that can be drawn is that animals can detect two conspecifics in the same tank. So the debate as to whether it is individual recognition or recognition of aggressive state occurring is still open to interpretation. Some authors suggest that recognition occurs through visual cues such as initiation or rate of escalation (Thorpe and Ammerman, 1978; Winston and Jacobson, 1978). If crayfish use aggressive state as a recognition signal, it may be due to some aspect of the physiological state of a crayfish and not individual recognition (Copp, 1986).

Chemical signals are important for many crayfish behaviors such as foraging, predation, and mating. Crayfish use chemoreception to find food sources, regardless of the substrate type, through chemical cues by orientating to odor plumes emanating from food (Moore and Grills, 1998). Some chemical signals have also been shown to be alarm signals. Crayfish avoid areas where a conspecific has been injured or killed based on the chemicals released from an injured or dead conspecific (Hazlett, 1985a, 1990). In social situations, chemical signals allow crayfish to distinguish between male and female conspecifics (Ameyaw-Akumfi and Hazlett, 1975; Dunham and Oh, 1996), and to identify the correct species in mate choice (Tierney and Dunham, 1982). Ameya-Akumfi and Hazlett (1975) discovered that male P. clarkii can distinguish females from males through a putative sex pheromone. Dunham and Oh (1996) found the same behavior occurs in female P. clarkii.

Since both chemical communication and status relationships are integral parts of a crayfish's life, we are interested in the neurochemical, behavioral, and chemical mechanisms that underlie social behavior in crayfish.