Pros and cons of a framework for evaluating potential pain in decapods

The rigorous framework for research into potential pain in decapods was successful in allowing legislators in the United Kingdom to evaluate a complex scientific issue. However, it might produce problems for research. I discuss doubts about the usefulness of the eight criteria. Some have yet to receive any investigation and others do not allow much inference about pain. In addition, some existing studies are not covered in the framework. Most worrying, however, is the potential for stifling future research of novel areas that are excluded from the framework

Do arthropods respond to noxious stimuli purely by reflex?

Mikhalevich & Powell (2020) argue that it is wrong to dismiss the idea of sentience in invertebrates. Here, I expand on the evidence for crustaceans responding to noxious stimuli in ways that are not explained by mere reflexes, and that are consistent with pain. I consider the idea that male praying mantids must not feel pain because they may continue to mate whilst being consumed by the female. I finish with thoughts about the idea that because robots may be constructed to act as if they experience pain, the argument that animals might experience pain is diminished

Might insects experience pain?

The aim of this commentary is to expand the discussion about subjective experience to other arthropods, notably crustaceans. Various species of crustaceans show responses consistent with their feeling pain. Hermit crabs also show prolonged investigation of new shells. They clearly attend to and integrate information from a wide variety of sources that enable them to evaluate the quality of the new shell relative to their current shell. These observations too are consistent with their having subjective experience

Assessing negative and positive evidence for animal pain

Jonathan Birch suggests that we should take one well-conducted study that produces results consistent with the idea of pain as being sufficient to invoke the animal sentience precautionary principle. Here, I consider how to balance negative and positive results from such studies using examples from my own work. I also consider which criteria of pain might provide strong inference about pain and which may prove to be weaker

Do arthropods respond to noxious stimuli purely by reflex?

Mikhalevich & Powell (2020) argue that it is wrong to dismiss the idea of sentience in invertebrates. Here, I expand on the evidence for crustaceans responding to noxious stimuli in ways that are not explained by mere reflexes, and that are consistent with pain. I consider the idea that male praying mantids must not feel pain because they may continue to mate whilst being consumed by the female. I finish with thoughts about the idea that because robots may be constructed to act as if they experience pain, the argument that animals might experience pain is diminished

Fish learn collectively, but groups with differing personalities are slower to decide 1 and more likely to split

We tested zebrafish shoals to examine whether groups exhibit collective spatial learning and whether this relates to the personality of group members. To do this we trained shoals to associate a collective spatial decision with a reward and tested whether shoals could reorient to the learned location from a new starting point. There were strong indications of collective learning and collective reorienting, most likely by memorising distal cues, but these processes were unrelated to personality differences within shoals. However, there was evidence that group decisions require agreement between differing personalities. Notably, shoals with more boldness variation were more likely to split during training trials and took longer to reach a collective decision. Thus cognitive tasks, such as learning and cue memorisation, may be exhibited collectively, but the ability to reach collective decisions is affected by the personality composition of the group. A likely outcome of the splitting of groups with very disparate personalities is the formation of groups with members more similar in their personality