Defensive strategies of European spiny lobster Palinurus elephas during predator attack

Abstract

The aim of the present work was to reveal the behaviour of the European spiny lobster Palinurus elephas (Fabricius, 1787) during encounters with predators. The study was conducted in a tank, exposing lobsters individually or in groups to a single specimen of the European conger eel or the common octopus. The behaviours of the lobsters, their sounds and the behaviours of the predators were recorded using a digital audio-video underwater acquisition system and analysed. A behavioural event not found in literature, dubbed 'Alert' by the authors, was described. The results showed that the most recurrent events were Alert, Point and Whip, which have the function of controlling the predator with the antennae, while maintaining the predator-prey distance. Moreover, a strong association between Tail Flip and Lunge (events that were stimulated in response to an imminent danger to life) with the sounds emitted by lobsters was observed. Significantly more sounds were emitted during the tests with single lobsters compared to grouped lobsters. As a result of the present study, the European conger eel may also be considered a potential natural predator of the European spiny lobster.

Acoustic behaviour of the European spiny lobster Palinurus elephas

“…Mean number (± standard deviation) of acoustic signals produced by the lobsters under different conditions nated by ultrasound frequencies) and without any association with a particular behavioural event. During the trials with an octopus, both the ultrasound screech and the audible rasp were recorded, and the latter were always associated with anti-predator behaviours: tail flip, lunge, parry, whip and point (Buscaino et al 2011). As shown in Fig.…”

“…The audible rasp occurs in association with specific anti-predator behaviours (tail flip, lunge, parry, whip and point) (Buscaino et al 2011) consisting of largeamplitude body movements that significantly affect the movements of the antennae. Various functional hypotheses have been offered as explanations for stridulation in lobsters.…”

“…Overall, we performed 20 trials: a single lobster (no stimuli/stress: n = 5 trials), grouped lobsters (only conspecific stimuli/stress: n = 5 trials), a single lobster with a predator (predation stimuli/stress: n = 5 trials), and grouped lobsters with a predator (conspecific stimuli/stress and predation stress: n = 5 trials). The synchronised audio-video system also recorded the behaviour of the lobsters visually (Buscaino et al 2011) and permitted us to characterise and define the acoustic signals produced in association with particular behavioural events.…”

“…The rasp duration, number of pul ses per rasp and pulse rate have only been assessed after stress caused by human manipulation, and the spectral characteristics of the rasp were not studied (Patek & Oakley 2003). Moreover, studies on the production of sound by spiny lobsters have primarily focussed on the audible range, and information on acoustic emissions under different ecological conditions remains rare and fragmentary (Patek & Oakley 2003, Buscaino et al 2011, Staaterman et al 2010. Information about the context in which lobsters emit acoustic signals is important because it allows improved knowledge of the ecological role of these signals.…”

Physiological and agonistic behavioural response of Procambarus clarkii to an acoustic stimulus

“…We identified the agonistic behavioural events reported in other decapods (Buscaino et al, 2011a) and other Procambarus species (Bergman and Moore, 2003;Buscaino et al, 2012): fights and tail flips. Moreover, we considered an event to be an 'encounter' when a specimen approached another one without any threat display (Bergman and Moore, 2003;Buscaino et al, 2012).…”