Tonically immobilized selfish prey can survive by sacrificing others

Abstract

Death-feigning, also called tonic immobility, is found in a number of animal species across vertebrate and invertebrate taxa. To date, five hypotheses have been proposed for the adaptive significance of tonic immobility. These are that tonic immobility is effective for prey because (i) avoiding dead prey is safer for predators, (ii) immobility plays a role in physical defence, (iii) immobility plays a role in concealment and/or background matching, (iv) predators lose interest in unmoving prey, and (v) the characteristic immobilization posture signals a bad taste to predators. The fourth and fifth hypotheses have been considered suitable explanations for tonic immobility of the red flour beetle against its predator, the jumping spider. In the present study, we used chemical analyses of secretions by the red flour beetles under attack by the jumping spider to reject the fifth hypothesis for this system. More importantly, we tested a selfish-prey hypothesis for the adaptive significance of death-feigning as an anti-predator strategy, in which individuals adopting tonic immobility survive by sacrificing neighbours. Findings showed that survival rates of feigners were higher when in the presence of non-feigners or prey of a different species, compared to when alone, thus confirming our selfish-prey hypothesis. In summary, our results suggest that immobility following a spider attack is selfish; death-feigning prey increase their probability of survival at the expense of more mobile neighbours.

Distance-dependent switching of anti-predator behavior of frogs from immobility to fleeing

“…Predictions of escape theories have been confirmed and developed by experimental studies using real prey animals, mainly lizards and crickets (Cooper 1997(Cooper , 2003Cooper et al 2003;Lagos et al 2014). The repertoires and effectiveness of anti-predator tactics against real predators have also been reported (Wasson and Lyon 2005;Ford and Reeves 2008;Miyatake et al 2009;Toledo et al 2011). In spite of the piles of studies reporting anti-predator tactics, studies that compare multiple tactics for clarifying the optimal decision of tactic choice are scarcely explored (but see Ducey and Brodie 1983), especially those from the view point of the optimal tactic-choice model, such as the Broom and Ruxton model (2005).…”

Thanatosis in the Brazilian seahorse Hippocampus reidi Ginsburg, 1933 (Teleostei: Syngnathidae)

“…Feigning death is a secondary strategy, adopted when the animal has already been captured by the predator. This can prevent sequential predator attacks, allowing for possible escape (Miyatake et al 2004) or as an anti-stimulus for predators that only attack moving prey (Miyatake et al 2009). Seahorses have no specific predators, but some records are found regarding predation by crabs, tuna, shark, and anglerfish (Lourie et al 1999).…”

Gravidade psicopatológica em mulheres vítimas de violência doméstica

“…A dissociação peritraumática pode estar ligada ao que etiologicamente é estudado como imobilidade tônica, comportamento encontrado em vários vertebrados e invertebrados, usado como mecanismo de defesa para situações extremas de perigo 17 .…”