page_title: Pain in invertebrates
section_title: Insects
hierarchical_section_title: Pain in invertebrates / Opioid receptors, effects of local anaesthetics or analgesics / Insects
caption_attribution_description: English: Male of cricket Gryllus assimilis. Español: Macho de grillo Acheta domesticus.
context_page_description: Pain in invertebrates is a contentious issue. Although there are numerous definitions of pain, almost all involve two key components. First, nociception is required. This is the ability to detect noxious stimuli which evokes a reflex response that moves the entire animal, or the affected part of its body, away from the source of the stimulus. The concept of nociception does not imply any adverse, subjective feeling; it is a reflex action. The second component is the experience of "pain" itself, or suffering—i.e., the internal, emotional interpretation of the nociceptive experience. Pain is therefore a private, emotional experience. Pain cannot be directly measured in other animals, including other humans; responses to putatively painful stimuli can be measured, but not the experience itself. To address this problem when assessing the capacity of other species to experience pain, argument-by-analogy is used. This is based on the principle that if a non-human animal's responses to stimuli are similar to those of humans, it is likely to have had an analogous experience.
context_section_description: Morphine extends the period that crickets remain on the heated surface of a hotplate.
caption: The house cricket, Acheta domestica
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