Coevolutionary attack and avoidance strategies in predators and grouping prey.

The formation of groups by prey is one of the most widespread evolutionary responses to predation. However, while the anti-predation benefits provided to prey within groups have been extensively explored in the literature, the subsequent response of predators to grouping behaviour has lacked attention. In particular, what strategies predators use to attack grouping prey, and whether predation strategies have evolved to explicitly exploit the behaviour of prey groups, remains underexplored. In this review, we discuss the behavioural strategies predators have evolved to counteract the collective defences of prey groups, and in some cases capitalize on the prey's grouping behaviour. Specifically, we focus on the different strategies predators use to break apart and disrupt groups, while also exploring how predators capitalize on cohesion and coordinated movement to increase the likelihood of a successful attack. Overall, this review challenges the assumption that grouping is universally advantageous for prey, showing that predators have evolved a variety of successful strategies to overcome, and even exploit, grouping prey. This article is part of the theme issue 'Multi-predator feeding aggregations in the pelagic waters'.