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Cephalopod Sentience - the study of the octopus


Octopus Covering Camera with Caption text
Cephalopod Sentience

The aliens have invaded! They have eight arms, three hearts, nine brains, and bleed blue blood. They even shapeshift and change color to match their surroundings. The octopus has been making headlines for decades, from the fantastic story of the Kraken to the lesser-known but equally incredible stories of escape artist octopuses wreaking havoc on their caregivers. Most recently, you may have heard of events in the UK based around these alien creatures. A group of scientists from the London School of Economics and Political Science reviewed the animal welfare law; after evaluating over 300 scientific studies (7 Crump et al.), they concluded that octopus and many decapods (shrimp, crabs, and lobsters), and other types of cephalopods show evidence of being sentient. Determining which creatures are sentient is based on eight criteria;


  1. Possession of pain receptors.

  2. The ability to process information and respond accordingly.

  3. The ability to react and gain information from the pain (what caused the pain, where is the pain, Ect.)

  4. Response affected by potential local anesthetics (temporary numbing pain relievers) and analgesics (pill-type pain relievers).

  5. Balance threat against reward (motivational trade-offs).

  6. Self-protection in response to threat/ injury.

  7. The ability to be able to learn new things outside their natural environment.

  8. The animal prefers local anesthetics or analgesics when injured.


If animal studied falls into more than one of these categories, they could be considered sentient. We've talked a lot about the criteria of being sentient, but what is sentience? Simply put, it is responsive consciousness, or the capacity to have both painful and pleasurable feelings. A few other sentient animals are; dogs, cats, birds, dolphins, and bears. We are also learning as science advances, many fish and various invertebrates are also sentient. Why does it matter that an animal is labeled as sentient? Labeling animals as sentient allows us to treat these animals humanely. As a person, you wouldn't want to be chopped on the head and put in a stew barely alive. That is unnecessary pain and is not ethical, so by discovering which animals are sentient, we can adjust animal welfare laws to best suit that animal and keep our fishing practices ethical and safe. Sentient beings have interests. Therefore, putting these animals through severe harm is unethical and even illegal. The team at LSE conducting this research used the eight criteria to identify how strong the evidence of sentience is by using confidence levels; VH- Very high, H- high, M- Medium, L-light, and VL- Very low. Below is the summary of their findings:



Our main focus will be the evidence of cephalopods. But we encourage you to read the entire review on your own time; it will be linked at the end.


Criteria one is the Possession of pain receptors. The scientists say that the pain receptors would only fire under extreme or repeated touch allowing the octopus to recognize that it was sustaining tissue damage. Proving that Octopus and other Cephalopods have different sensory neurons that respond to varying types of Pain or touch feelings. This almost absolutely proves the octopus's qualifications for criteria one; it does prove by itself that octopuses are sentient. Still, it helps us understand the octopus’s mind and how it responds to things relative to how other sentient beings would respond.

Criteria two is the ability to process information and respond accordingly. With very high confidence, scientists found that cephalopods have a very complex brain capability to integrate data and learn from its collected information. The octopus brain contains ~170 million nerve cells and can combine data from the arms with information retrieved with the eyes to guide movements. It's no wonder they can control all those arms.

Criteria Three is the ability to react and gain knowledge from the pain or touch. There is an indirect reaction to touch and pain. However, this has not been demonstrated beyond all doubt. For this, it received high confidence.

Criteria Four is Response affected by potential local anesthetics. Again, Birch et al. gave octopus high confidence. The LSE researchers found a 2021 study that provided evidence of the modified response of an octopus when treated with lidocaine—checking off just another box towards complete sentience identification.

Criteria five, balance threat against reward. No study gave enough evidence to solidify confidence in criteria 5. So the scientist came up with the hypothesis that cephalopods will change priorities when injured or threatened.

Criteria six Self-protection in response to threat/ injury. With Octopus, it's hard to dispute this criterion. If you have ever seen an ocean documentary, you've more than likely seen an octopus use shells, trash, and various debris found on the sea floor to create armor to protect itself. They have also been seen wiping a wound as if to scrape off anything that may hurt it more.

Criteria seven, The ability to learn new things outside their natural environment. The Octopus has shown this time and time again with various puzzles cre