Chemical communication in lobsters

Abstract

Lobsters are fascinating animals that use chemicals as messages regarding their sexual status, their standing in a social hierarchy, and whether they affiliate with or avoid conspecifics. This, plus their economic importance, makes them important models for the study of intraspecific chemical communication. Our chapter is an overview of these processes, including the types of interactions between lobsters influenced by chemicals, how those interactions are affected by chemicals, and how these chemicals are detected. Since "lobster" refers to a common body plan rather than a taxonomic group and thus includes animals of differing phylogenetic relatedness and lifestyles - most notably clawed lobsters, spiny lobsters, and slipper lobsters, their use of chemicals in intraspecific interactions is diverse. Whenever possible, we compare the different groups of lobsters, though the amount of data available for relevant behaviors varies with the lifestyle of lobsters. Clawed lobsters use urinary chemicals processed by the olfactory pathway to identify previous opponents and maintain a stable social order, which is important because only the most dominant males will mate. After a hierarchy has been established by fighting, subsequent rematches are shorter and less violent, with urinary chemicals playing a key role in this process. Mate choice and mating behavior are also mediated by urinary olfactory cues. These behaviors are disrupted when one of the animals either has a compromised olfactory sense or is not allowed to release urine. Although there is less available data, the picture seems similar in spiny lobsters, with females using urinary chemicals from males as one of the cues in mate selection. Both spiny and slipper lobsters form dominance hierarchies, but little is known about how they are influenced by chemical signals. Conversely, spiny lobsters have been extensively studied regarding the mechanisms of aggregation and avoidance. Aggregation is mediated by urine-borne chemicals and avoidance is mediated by blood-borne chemicals, both processed by the olfactory system. Molecular identification of these compounds will be critical in allowing researchers to study the neural processing of intraspecific chemicals.