The first study showed that mammals and octopuses are more similar than we thought – they also feel emotional distress when hurt physically.
Pain isn’t located where the injury has taken place, it is a more complex experience in mammals, and scientists used to doubt this invertebrates’ capacity, as they are built with a much simpler nervous system.
Only a small number of scientists focused to understand the ability of octopuses to experience negative emotions even octopuses have the most complex neurological system amongst invertebrates.
Neurobiologist Robyn Crook from San Francisco State University provided pioneering insights in this matter using the same methods to test pain on lab rodents and octopuses. He lead experiments for years, applying detailed measurements of involuntary behaviours associated with distress and neural activity.
He received three different confirmation that octopuses experience unpleasant emotions when they encounter physical pain.
How Octopuses Respond to Pain Stimuli
It is no easy work to understand animals’ feelings and emotions, especially cephalopods, that are so fundamentally different from us. However, Crook outlines that the behaviours displayed by the octopuses in the testing labs show that they are not unlike rodents regarding the lasting effects in their affective disposition, what we call in human terms “attitudes”, “moods” etc.)
“Even in the absence of proof on conscious awareness or sentience in cephalopods, it remains clear that the responses demonstrated by octopuses in this study are so similar to those that would be expressed by mammals experiencing pain, that a reasonable, cautionary argument can be made that internal state of these disparate species is likely also similar.”
Former studies have shown that octopuses are able to respond spontaneously to harmful stimuli by knowing to avoid adverse environments and situations. In Crook’s study, the subjects responded distinctively after a single training session in a box with three chambers. The octopuses that underwent a painful acetic vaccine in one arm displayed aversion toward the room they received the injection. On the other hand, the subjects that received an unpainful saline injection showed no resistance towards being placed in the same chamber.
Also, the octopuses that have been given an analgesic(lidocaine) after the painful shot showed a preference towards the chamber they felt the pain relief.
This action of putting themselves out of a threatening place is a strong indicator of a past affective experience. Also, the octopuses were able to distinguish between different types of pain in the body and their intensities. After the shot, they started to groom the painful area for the entire 20-minute training trial and try to eliminate a small part of the skin with their beak.
Misterious Link Between Octopuses and Mammals
Crook used electrophysiological recordings to measure the effects exerted by the acid injections, and the records pinpoint an extensive peripheral response in the pathway to the brain. Also, the signals suddenly stopped after the analgesic administration, which outlines the presence of emotional distress again.
The experiment demonstrates the presence of a “lasting, negative affective state in octopuses”. Ongoing pain was only acknowledged in mammals, and it’s astonishing to see that invertebrates own this ability despite the neurological variations.
Science amazed us with another breakthrough earlier this week – cuttlefish are able to pass the marshmallow test, which is a tool that estimates children’s self-regulation.
“Our goal with this study was to move the question of invertebrate pain beyond reasonable doubt,so that efforts to better regulate their humane use can proceed with a strong evidentiary foundation that until now, has been lacking.”
These findings can only dig into human awareness of the animal kingdom and raise a bunch of ethical question, such as how should be cephalopods handled and regarded from now on and what is the best treatment we can provide for their well-being.