Motivational trade-offs and potential pain experience in hermit crabs

Shock avoidance by discrimination learning in the shore crab (Carcinus maenas) is consistent with a key criterion for pain

“…These findings indicate swift avoidance learning, which is a key criterion/expectation for pain experience, but this alone does not prove that crabs can experience pain. Other studies have shown prolonged rubbing after noxious stimuli (Barr et between shock avoidance and holding resources of different values (Elwood and Appel, 2009;Appel and Elwood, 2009a), prolonged memory of shock and giving up vital resources to avoid shock (Appel and Elwood, 2009b), which are all consistent with the concept of pain. Furthermore, injury results in marked physiological changes that mirror those related to corticosteroid release in vertebrates (Patterson et al, 2007).…”

“…Leaving a shelter in the field, even when being severely disturbed by a potential predator, is likely to be a tactic of last resort. Hermit crabs abandon their shell if the abdomen is shocked and some even walk away from that essential resource (Elwood and Appel, 2009;Appel and Elwood, 2009a;Appel and Elwood, 2009b). When vertebrates are induced to give up a valuable resource by an aversive experience, the idea of pain is typically invoked (Dunlop et al, 2006;Millsopp and Laming, 2008).…”

Trade-offs between predator avoidance and electric shock avoidance in hermit crabs demonstrate a non-reflexive response to noxious stimuli consistent with prediction of pain

“…This long-term reduction of tissue damage by avoiding the noxious stimuli in the future is a key criterion for pain (Bateson, 1991). Further, hermit crabs that have been shocked within their shell show an increased likelihood of changing shells that lasts at least 24hrs (Appel & Elwood, 2009a;Elwood & Appel, 2009) indicating a long-term shift in motivation to avoid the shell in which shock was experienced. Further evidence consistent with pain is a general anxiety after noxious stimuli, as evidenced by crayfish avoiding brightly lit areas of a maze after being repeatedly subject to an aversive electric field in another arena (Fossat et al, 2014(Fossat et al, , 2015.…”

Subjective resource value and shell abandoning behavior in hermit crabs

“…Beyond the examples given above, a broad literature search returned very few studies on shell abandoning behavior of these animals (but see, Appel and Elwood, 2009;Elwood and Appel, 2009); a concerning discovery given the increasingly frequent and extensive scale of coastal disturbance (e.g., dredging, land reclamation and increased coastal erosion; Airoldi and Beck, 2007) that increase the risks of burial and entrapment for crabs and other species. Given that the threat of burial and entrapment will differ across a spectrum of estuarine and coastal habitats, we theorized that benthic fauna inhabiting different intertidal zones may exhibit contrasting responses with respect to resource holding potential and subjective resource value (sensu, Gherardi, 2006).…”