The trade-off between feeding, mate seeking and predator avoidance in copepods: behavioural responses to chemical cues

The behavioural responses of adult Temora longicornis to chemical signals from predators and potential sexual partners was studied using an automated three-dimensional (3-D) tracking system and a 2-D high-resolution filming set-up. The animals adapted their swimming speed and turning behaviour in reaction to chemical signals to increase or decrease encounter probability with other organisms. Female copepods were shown to react to the smell of males with little ‘hops’, quite distinct from both their normal smooth swimming motion and escape responses. These hops are likely to be signals intended to increase the encounter probability with males. Swimming behaviour was shown to be a trade-off between conflicting motivations such as predator avoidance on the one hand, and the search for food and sexual partners on the other.