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Pain in crustaceans is contentious as there is debate whether they are capable of the subjective experiences of pain and suffering, or only the non-subjective, reflex response of nociception. Most definitions of pain involve the two key components of nociception and suffering. Nociception is an 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 simple reflex action, not processed by the brain. Suffering is the subjective experience of the pain; the internal, emotional interpretation of the nociceptive experience and therefore a private, emotional experience. Suffering 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. In vertebrates, endogenous opioids are neurochemicals that moderate pain by interacting with opioid receptors. Opioid peptides and opioid receptors occur naturally in crustaceans, and although "...at present no certain conclusion can be drawn",〔 some have interpreted their presence as an indication that crustaceans may experience pain.〔〔 Opioids may moderate pain in lobsters similar to the way they moderate pain in vertebrates.〔 ==Background== The belief that non-human animals might not feel pain in the same manner as humans dates back to at least the 17th century, when French philosopher René Descartes argued that animals do not experience pain because they lack consciousness.〔(The Ethics of research involving animals ) Nuffield Council on Bioethics, Accessed 27 February 2008 〕 Bernard Rollin of Colorado State University, the principal author of two U.S. federal laws regulating pain relief for animals, wrote that researchers remained unsure into the 1980s as to whether animals experience pain. Veterinarians trained in the U.S. before 1989 were simply taught to ignore animal pain.〔 Cited in Carbone 2004, p. 150.〕 In his interactions with scientists and other veterinarians, Rollin was regularly asked to prove that animals are conscious and to provide scientifically acceptable grounds for claiming that they feel pain.〔 Veterinarian and author Larry Carbone has written that the view that animals feel pain differently is now a minority view. Academic reviews of the topic are more equivocal, noting that although the argument that animals have at least simple conscious thoughts and feelings has strong support, some critics continue to question how reliably animal mental states can be determined.〔 Pain is a private experience and therefore we cannot know with certainty whether other animals, or other humans, experience pain. However, the capacity for experiencing pain can be inferred using argument-by-analogy and physiological and behavioral reactions.〔Sherwin, C.M., (2001). Can invertebrates suffer? Or, how robust is argument-by-analogy? Animal Welfare, 10 (supplement): S103-S118〕〔Elwood, R.W., (2011). Pain and suffering in invertebrates? Institute of Laboratory Animal Resources Journal, 52(2): 175-84 ()〕 Specialists currently believe that all vertebrates can feel pain, and that certain invertebrates, like the octopus, might too. Nociceptors, the neurones required for the sensation of pain, have been found in nematodes, annelids, molluscs〔St John Smith, E. and Lewin, G.R., (2009). Nociceptors: a phylogenetic view. Journal of Comparative Physiology. A. Neuroethology Sensory Neural and Behavioral Physiology, 195: 1089-1106〕 and in the arthropod, Drosophila, despite earlier claims that nociceptors were absent in insects. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pain in crustaceans」の詳細全文を読む スポンサード リンク
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