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Animals utilize an incredible array of traits for offence and defence during conflict. These traits range from exaggerated morphological structures such as the antlers of stags and the horns of beetles, to an arsenal of noxious chemicals emitted, secreted, and injected. However, the breadth of these traits appears to be underappreciated in our current thinking about aggression in animals. Use of the term "weapon" in the current literature is largely restricted to studies of conspicuous morphological structures used by males during contests over access to females, and as a result, our understanding of other types of weapons is limited. In this article, I explore the diversity of traits utilized by animals to manipulate and control the behavior of other individuals in a number of agonistic contexts, with the aim to encourage a reappraisal of the way in which behavioral and evolutionary biologists view animal weapons. I discuss the advantages of including this broader range of traits in studies of animal weaponry and explore the unifying features that distinguish animal weapons from other traits. [ABSTRACT FROM AUTHOR]

Fighting experience (specifically winning or losing a fight) can significantly alter boldness, a component of resource-holding potential (RHP). Previous studies have shown that both the repeatability of boldness and mean-level boldness can be affected by fighting experience and that these effects are strongest in the recipients of agonistic behaviour. However, whether these postfight changes in boldness impact future contest success and whether subsequent contests further affect boldness remain unknown. Furthermore, little is known about the effects of the specific tactics used within a fight (within-fight experience) and how these might influence future fight performance and boldness. Here, we investigated the relationship between fighting success and boldness (measured as recovery time when startled) across repeated contests in the beadlet sea anemone, Actinia equina , measuring boldness on five occasions before, between and after two contests. We found that boldness (both repeatability and mean-level) was generally robust to the effects of fighting experience, apart from a decrease in the immediate boldness of losers after their second fight. Furthermore, we found that while prefight boldness significantly predicted fighting success and the level of aggression used in an individual's first fight, it did not predict victory or aggression in the second fight. Our findings thus indicate that different traits may be important in determining fighting success in consecutive fights and, moreover, that fighting experience may alter which traits contribute to an individual's RHP. [ABSTRACT FROM AUTHOR]

Theoretical models of injurious animal contests, such as the cumulative assessment model (CAM), predict that an individual's decision to give up and retreat from a fight is determined by reaching a maximum cost threshold ( C max ). Under this model, an individual gives up when the accumulated costs of persisting exceed this threshold. CAM predicts that the velocity with which C max is reached depends on both the energetic (physiological) costs of remaining in the fight and the damage costs of injuries received. Here we propose that damage costs are accumulated not only by receiving injuries, but in some cases also by inflicting injury (attacking). We argue that these self-inflicted damage costs need to be incorporated into theoretical frameworks to fully understand what drives an individual to make the decision to give up, and we call for further research into this area. [ABSTRACT FROM AUTHOR]