WikiFindings

Healthier beadlet anemones are more likely to use weapons to injure others during fights

Background

Fighting can require lots of effort. This puts stress on the immune system, reducing our ability to fight illness. This is because the energy that would normally be used to prevent disease is used during and recovering from the fight. Instead, animals might avoid physical fights or use noncontact aggressive displays. The beadlet sea anemone is one of the simplest animals to take part in physical fights. Injuries are caused not only by being attacked, but also from injuring others. These anemones have stinging tentacle weapons which they scrape across enemies. These leave behind patches of stingers which damage the body. During this, stingers are ripped from the attacker’s body, damaging themselves in the process. This tactic makes them an interesting species for learning about aggressive behaviour and immune response (our ability to fight disease) during animal fights. It is commonly believed that healthier animals are more likely to be aggressive and win fights. However, it is unclear whether this is actually true.

Findings

After testing the effect of fighting on the strength of immune responses, we suggest that healthier anemones are not always more likely to win, as previously believed. Instead, healthier anemones are more likely to use their stinging weapons to cause injury than those fighting infection. Although anemones that use their weapons also suffer self-inflicted injury, they are able to maintain their health after fighting. Whereas, victims suffer a decline in health afterwards. Additionally, winners regain their strength much quicker than losers. In fact, winners start to return to their pre-fight health within just 24 hours.

Implications

Our findings show that beadlet anemones use different fighting tactics depending on the condition of their immune system. While healthier individuals are more aggressive, they are not necessarily more likely to win. However, anemones that do win might be more likely to win in the future, as they recover more quickly. Overall, we show that fight success does affect health, while health in turn will affect an animal’s decision to fight. This research improves our knowledge of what causes beadlet anemones and possibly other animals to behave a certain way during aggressive scenarios. By increasing our understanding of how health and immune response affects behaviour, we may also discover why and how such behaviours evolve.