Effects of Acetic Acid and Morphine in Shore Crabs, Implications for the Possibility of Pain in Decapods.

Noxious chemicals, coupled with morphine treatment, are often used in studies on pain in vertebrates. Here we show that injection of morphine caused several behavioural changes in the crab, , including reduced pressing against the sides of the enclosure and more rubbing and picking at the mouth parts and, at least for a short time, more defensive displays. Subsequent injection of acetic acid into one rear leg caused rubbing of the injected leg and the injected leg was held vertically off the ground.

Negative Social Exchanges During the Pandemic, Loneliness, and the Mediating Role of Stress and Feeling Misunderstood Among People at High-Risk for COVID-19 Related Complications.

The goal of this study was to investigate the links between social interactions and mental health for people who are high-risk for COVID-19 complications. Specifically, we tested the relationships between negative social exchanges during the pandemic and loneliness through two mediators: stress and feeling misunderstood about one's health status. Data were collected via Amazon's MTurk from participants ( = 271) who self-identified as being high-risk for COVID-19.

Trade-Offs between Avoidance of Noxious Electric Shock and Avoidance of Bright Light in Shore Crabs Are Consistent with Predictions of Pain.

The suggestion that decapod crustaceans might experience pain has been dismissed by some authors who claim decapods only respond to noxious stimuli by nociceptive reflexes. Because reflexes do not require complex neuronal processing, but pain does, demonstrating reflex responses to noxious stimuli would not support the case for pain. Here, we report an experiment in which shore crabs are repeatedly placed in a light area (20 trials), but the animals can avoid the light by moving to a dark shelter.

The Effects of Caustic Soda and Benzocaine on Directed Grooming to the Eyestalk in the Glass Prawn, , Are Consistent with the Idea of Pain in Decapods.

Acceptance of the possibility of pain in animals usually requires that various criteria are fulfilled. One such criterion is that a noxious stimulus or wound would elicit directed rubbing or grooming at the site of the stimulus. There is also an expectation that local anaesthetics would reduce these responses to damage.

Behavioural Indicators of Pain and Suffering in Arthropods and Might Pain Bite Back?

Pain in response to tissue damage functions to change behaviour so that further damage is minimised whereas healing and survival are promoted. This paper focuses on the behavioural criteria that match the function to ask if pain is likely in the main taxa of arthropods. There is evidence consistent with the idea of pain in crustaceans, insects and, to a lesser extent, spiders.