Invertebrate Sentience: Do Invertebrate Experiences Deserve Respect & Welfare Protection?

Posted byKeiron Derek BrownPosted inBlog, entoLIVE Blog

To be sentient is to have positive or negative experiences, such as experiences of pain, pleasure, comfort, warmth, hunger, anxiety or joy. Humans are sentient, but are we alone? In the UK, a new law requires all policymakers to have due regard for animal sentience. This law has given new urgency to the question: which other animals are sentient? Might some invertebrates, such as octopuses, crabs, snails, or even insects, have experiences that deserve respect and welfare protection? Prof Jonathan Birch played a key role in amending the new legislation to include octopuses, crabs and lobsters. Here he talks about the evidence for invertebrate sentience.

Q&A with Prof Jonathan Birch

Jonathan Birch is a Professor of Philosophy at the London School of Economics and Principal Investigator (PI) on the Foundations of Animal Sentience project. In 2021, he led a “Review of the Evidence of Sentience in Cephalopod Molluscs and Decapod Crustaceans” that led to invertebrate animals including octopuses, crabs and lobsters being included in the UK government’s Sentience Bill. In addition to his interest in animal sentience, cognition and welfare, he also has a longstanding interest in the evolution of altruism and social behaviour. His first book, The Philosophy of Social Evolution, was published by Oxford University Press in 2017.

  • Do octopuses have more than one brain?
    People wonder a lot about octopuses because they have a substantial amount of the nervous tissue in their arms and then they have ganglia at the top of the arms that are linked, as well as the central brain. There is then a question about if each of those arms has subjective experiences of their own. However, other octopus experts will argue that the central brain is still in control, so we don’t have as detailed a picture as we’d like about how autonomous each of the arms is.
  • Can we study sentience in a way that doesn’t focus on human experience to versions of sentience that don’t exist in humans?
    We have to be open to the likelihood that animals may have sensory experiences that do not exist in humans – that we wouldn’t even have words for as we don’t experience them. This is particularly true of animals that have sensory abilities that we don’t have, for example, animals that have electroreception. What does that feel like? We don’t have words for that and the language that we have for talking about sentience is incredibly anthropocentric and limited so we do need to find frameworks for including this. However, for communicating with policymakers terms like pain are quite useful for conveying the urgency and importance of what we are talking about.
  • Are there ways other than inducing pain to study sentience?
    I would love to see the field of animal sentience move away from pain and no longer focus on such an extent to it. I’d like to see more of a focus on the positive side of sentience. The issue is that there is a lack of rigorous ways to study states like joy and pleasure. There was a really interesting study that came out recently on play behaviour in bumblebees involving ball rolling in their environment, and it showed that they will roll balls when there is no reward associated with the behaviour and they will roll them just for the sake of rolling balls. Hopefully, these kinds of studies will lead to more similar studies focusing on the positive side of mental life as well as the negative.
  • How are the ethics of experiments using pain monitored?
    Where animals are protected there are measures in place. This just includes vertebrates and cephalopods as the law has not been amended to protect decapods or insects. For those that are protected, there is a framework that is based on the 3 R’s: replace, reduce, refine. Scientists have to get their work approved by an animal welfare review board and justify that they have really tried to minimise the number of animals involved, minimise the painfulness of the stimuli involved and replace animals wherever possible. Sadly animal research does still involve inflicting pain.
  • Are the experimental methods used suitable for invertebrates, such as insects, suitable for testing sentience when they experience the world differently?
    We’ve used experimental techniques used for mammals and where we’ve shown that invertebrates display the same behaviours we are able to take them as evidence of pain. The flip side of that is that if we’d conducted these experiments and invertebrates had not displayed these behaviours, does that mean that they don’t experience pain or simply that we’ve looked for it in the wrong way and we need to find ways of testing their behaviour that fits with their way of life?
  • Are the human medications working the same way in invertebrates as they do in humans?
    To me, it was amazing that it works at all! With octopuses, they have good effectiveness with a topical local anaesthetic (lidocaine) that goes on the skin and suppresses the first part of the pain pathway. It really seems to work right across the animal kingdom. It’s much more difficult to get painkillers that would be consumed and act on the brain and still work. With mammals the standard painkiller is opioids and these don’t appear to work on invertebrates.
  • What are your thoughts on octopus farming?
    Our report recommends against it as there will be animal welfare issues. It looks like it will happen in other countries so we need to think about if the UK should have measures to stop the import of octopus products coming from these farms.
  • Will a simar report to the decapod and cephalopod report be produced to assess insect sentience?
    The government has not commissioned such a report on insects. However, the review that we have conducted has been published and is available for researchers and policymakers. There are a lot of evidence gaps but there is also evidence, and where we have studied an insect group more closely (such as bees or fruit flies) the evidence suggests there is sentience present in insects.
  • Shouldn’t we assume everything is sentient and focus research on finding creatures that are not sentient?
    It depends on what you want the concept of sentience to do. For me and my team it’s important that once we recognise sentience in another animal, we must then take precautionary steps to protect welfare. It has to lead to action. We have to take action in the case of lobsters, crabs and octopuses to ensure these animals are not treated appallingly. If it is going to have that practical importance, there does need to be an evidence base there to justify and inform that. For example, there are microscopic animals where there is no evidence that they are sentient. This enables us to prioritise where we take action.

Literature references

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Published by Keiron Derek Brown

A blog about biological recording in the UK from the scheme organiser for the National Earthworm Recording Scheme.

3 thoughts on “Invertebrate Sentience: Do Invertebrate Experiences Deserve Respect & Welfare Protection?”

  1. Strange that science today equates neurons with brains and consciousness, when in reality they are just a physiological device to manage a swarm of cells and form a large life form. The number of neurons equate to the number and types of cells and whether they easily form groups or not. There is no proof or even theory as to how neurons might form consciousness and yet dogma suggests that without x number of neurons an animal can’t possibly be aware or feel anything. Descartes lives on, it seems.

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