Claim
There is broad scientific agreement that mammals, birds and fish can experience pain, and growing evidence that some invertebrates such as decapod crustaceans can too.
The animals we farm can feel pain. For fish the evidence is strong; for crabs and lobsters it is now considered substantial.
Why this rating: Multiple independent reviews and expert bodies reach the same conclusion for vertebrates; invertebrate evidence is newer but substantial.
Supported by multiple systematic reviews or large, consistent studies using different methods, with few plausible alternative explanations.
Explanation
Sentience cannot be measured directly. Scientists use criteria such as nerve receptors for harmful stimuli, brain processing, responses to painkillers, and learning to avoid harm.
Mammals, birds and fish meet most of these criteria. A 2021 review of over 300 studies concluded that octopuses and crabs also show strong evidence of sentience.
Limitations
- Subjective experience is inferred, not observed; how intense animals' experiences are remains debated.
Methodology
- Criteria-based assessment of behavioural, physiological and neurological evidence.
Sources for this claim
Each source links to our record of what it found, its limitations and what we used it for, with a link to the original.
- 1Review of the evidence of sentience in cephalopod molluscs and decapod crustaceans
Jonathan Birch, Charlotte Burn, Alexandra Schnell et al. (2021). Report commissioned by the UK Government (Defra).
- 2Defining and assessing animal pain
Lynne Sneddon, Robert Elwood, Shelley Adamo et al. (2014). Animal Behaviour.