Context

As part of the Sentient Futures' Project Incubator, I am currently studying the state of the art of shrimp sentience. I would be highly interested to get some insights into your own views on the specific topic of whiteleg shrimps.

Most of you may be familiar with Birch et al's sentience framework and the influence it had on the consideration of all decapod crustaceans to be regarded as sentient.

However, a recurring critique (such as from this post, this debate, or this conference paper) of this consideration is that Whiteleg shrimps (L. vannamei), and the Penaeid shrimps more broadly -- the most farmed shrimps/prawns by far -- actually shows little evidence for sentience criterions, and that the extrapolation from studies on other species is farfetched. This information gap is especially important for organizations working on decapod welfare, such as Shrimp Welfare Project, Crustacean Compassion or Rethink Priorities.

Comprehension note: Penaeid shrimps (Dendrobranchiata order) should not be confused with “true shrimps” that are species from the Caridea infraorder (see also this explanation). Penaeid shrimps are often called “prawns” and include those commonly named:

• The Pacific white shrimp (or White shrimp or King prawn)
• The Atlantic white shrimp
• The Giant tiger prawn (or Asian tiger shrimp or Black tiger shrimp)
• The Indian prawn

Considering the current literature, “true shrimps” and other decapod crustaceans arguably show relatively satisfying evidence on multiple sentience markers. The information gap mostly relies specifically on Penaeid shrimps, including Whiteleg shrimps.

To argue that all decapod crustaceans should be considered sentient, Birch et al.’s report constructed sentience evidence by grading confidence for 4 neurobiological and 4 behavioral criterions, taking into account "both the amount of evidence for a claim and the reliability and quality of the scientific work".

Consider Birch et al. framework’s criterions, simply put and explained by Shrimp Welfare Project:

1. Possession of nociceptors - Let's say you accidentally touch a hot stove. Instantly, you will withdraw your hand from the stove.  A simple circuit of neurons saved your hand from a noxious stimulus (the hot stove) and prevented you from a burn.  This is referred to as nociception, named after nociceptors, the sensory receptors that detect the noxious stimuli.
2. Possession of integrative brain regions - Being able to integrate information from multiple different sensory sources.
3. Connections between nociceptors and integrative brain regions - Neural pathways connecting nociceptors to the brain (though it should be noted that the nervous system is organised very differently in elongated species such as shrimps, compared to compact species, such as crabs).
4. Responses affected by potential local anaesthetics or analgesics - If you have been to the dentist, you have probably been applied a substance to numb an area of your mouth so that the dentist can perform a procedure that otherwise would be uncomfortable or painful. That’s an anaesthetic, a substance that creates a lack of feeling. When used locally, anaesthetics reduce any sensation (not only pain) in a target area, while the individual remains conscious. If an animal responds differently to stimuli while under the influence of anaesthetics, this suggests the lack of feeling is mitigating an animal's experience of pain or distress.
5. Motivational trade-offs that show a balancing of threat against opportunity for reward - An animal can make a decision, like avoiding negative stimuli, such as an electric shock, rather than experience a positive stimuli (i.e. their actions cannot be explained by reflexes alone).
6. Flexible self-protective behaviours in response to injury and threat - Guarding, grooming or otherwise tending to an injured body part are protective behaviours. These are typically long term responses to injury, seen over periods of hours and days rather than seconds and minutes. In humans, protective behaviour is often controlled by the conscious feeling of pain, such as avoiding using an injured limb.
7. Associative learning that goes beyond habituation and sensitisation - If an animal can experience something, learn from it, and then make different decisions in the future, it provides good evidence of sentience.
8. Behaviour that shows the animal values local anaesthetics or analgesics when injured - For example, learning to self-administer anaesthetics or analgesics, or could learn to prefer a location where these can be accessed, or prioritise obtaining these over other needs (i.e. food) when injured.

Here is their summary for decapods:

We can note that, as Birch et al.’s report insists: “low/very low confidence implies only that the scientific evidence one way or the other is weak, not that the animal fails or is likely to fail the criterion”. We can legitimately argue that evidence is lacking for Penaeid shrimps, as the report acknowledges, but we can also argue that these taxons are genetically close enough for evidence to translate well, even if more specific research would be greatly valuable.

Poll

Considering this specific context, please find attached to this poll a few questions I’d be grateful for you to answer in the comments:

• How easily would you be able to change your confidence based on new evidence?
• Which criterions do you think are the most convincing to update your confidence?
• If you were to allocate money towards building more evidence for one or more criterions, which ones would you choose?
• Do you have other types of evidence that better influence your confidence?

Thanks a lot! :)

Transparency note: As part of Sentient Futures’ Project Incubator, my work is supervised by Aaron Boddy. This post has been reviewed and validated by Aaron, but is part of an independent research project.