Sentience in cephalopod molluscs: an updated assessment
Sentience in cephalopod molluscs: an updated assessment
This article evaluates the evidence for sentience - the capacity to have feelings - in cephalopod molluscs: octopus, cuttlefish, squid, and nautilus. Our framework includes eight criteria, covering both whether the animal’s nervous system might support sentience and whether their behaviour indicates sentience. There is very strong evidence of sentience in octopuses, which satisfy seven of the eight criteria. There is less evidence for cuttlefish and squid (4/8 criteria), although this is still substantial evidence. By contrast, whether nautiluses are sentient remains unknown (1/8 criteria), since this group of cephalopods have attracted little research. This reflects a general pattern: when criteria were not satisfied, this invariably reflected a lack of positive evidence. In no cases were we confident that a taxon failed a criterion. In our review, we explore the nuances of evidence for sentience, examining both neural and behavioural markers. This paper draws from and updates our review (Birch et al., 2021), shedding light on the implications for ethical treatment and welfare within this class of animals while also revealing areas where further research is needed
Schnell, Alexandra K.
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Browning, Heather
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Burn, Charlotte
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Crump, Andrew
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Birch, Jonathan
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Schnell, Alexandra K.
c3ef9566-077e-4bfa-b09e-72e9b275c04a
Browning, Heather
8d13aa04-7648-4403-b29c-11f7674f6618
Burn, Charlotte
e1e86d62-d220-4953-9855-d8e1d3a71b5d
Crump, Andrew
b50d4787-53da-4efd-a494-4020bbaf5b99
Birch, Jonathan
1710e22f-873a-4d7e-bbb3-43ecde11f8ae
Abstract
This article evaluates the evidence for sentience - the capacity to have feelings - in cephalopod molluscs: octopus, cuttlefish, squid, and nautilus. Our framework includes eight criteria, covering both whether the animal’s nervous system might support sentience and whether their behaviour indicates sentience. There is very strong evidence of sentience in octopuses, which satisfy seven of the eight criteria. There is less evidence for cuttlefish and squid (4/8 criteria), although this is still substantial evidence. By contrast, whether nautiluses are sentient remains unknown (1/8 criteria), since this group of cephalopods have attracted little research. This reflects a general pattern: when criteria were not satisfied, this invariably reflected a lack of positive evidence. In no cases were we confident that a taxon failed a criterion. In our review, we explore the nuances of evidence for sentience, examining both neural and behavioural markers. This paper draws from and updates our review (Birch et al., 2021), shedding light on the implications for ethical treatment and welfare within this class of animals while also revealing areas where further research is needed
Text
Schnell et al. Evidence of sentience, cephalopods
- Accepted Manuscript
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Biological Reviews - 2026 - Schnell - Sentience in cephalopod molluscs an updated assessment
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Accepted/In Press date: 19 December 2025
e-pub ahead of print date: 20 January 2026
Identifiers
Local EPrints ID: 508993
URI: http://eprints.soton.ac.uk/id/eprint/508993
ISSN: 1464-7931
PURE UUID: 5baa38ee-44b2-4df1-91a5-39b6ef7be914
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Date deposited: 09 Feb 2026 17:57
Last modified: 10 Feb 2026 03:17
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Author:
Alexandra K. Schnell
Author:
Heather Browning
Author:
Charlotte Burn
Author:
Andrew Crump
Author:
Jonathan Birch
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