How To Anesthetize an Octopus
sciencehabit writes Researchers have figured out how to anesthetize octopuses so the animals do not feel pain while being transported and handled during scientific experiments. In a study published online this month in the Journal of Aquatic Animal Health, researchers report immersing 10 specimens of the common octopus in seawater with isoflurane, an anesthetic used in humans. They gradually increased the concentration of the substance from 0.5% to 2%. The investigators found that the animals lost the ability to respond to touch and their color paled, which means that their normal motor coordination of color regulation by the brain was lost, concluding that the animals were indeed anesthetized. The octopuses then recovered from the anesthesia within 40 to 60 minutes of being immersed in fresh seawater without the anesthetic, as they were able to respond to touch again and their color was back to normal.
My brother in law is an anesthesiologist. Until I met him, I never realized how dangerous anesthesia is. You are basically turning over your life and your breathing/heart to one person's knowledge of drugs and how your body responds to them. Too much, and your heart or lungs stop working... too little, and you wake up and can feel and remember what's going on. The comforting stat is that only about 1 in 200,000 cases actually die, but just 25 years ago, it was 2 in 10,000.
For a field whose motto is "do no harm," I can see why they didn't want to do very much experimentation at all with anesthesia on babies -- the line between wake and death gets even smaller. And when you think about it, less than 150 years ago, ALL surgery was done without anesthetic..
Should be doable. They are quite capable of Pavlovian association. Knock them out, apply suitable stimulus - say, a moderately painful electric shock plus a distinctive scent in the water. Repeat enough time for your unsedated control group to show a fear response to the scent, and see if your sedated octopods have learned the association too.
I remember a little interview (in the New Scientist I think) with a marine biologist who said he stopped experimenting on octopi when, after inserting a probe into the head of an octopus he thought was anaesthetised, the octopus calmly raised its tentacle and pulled the probe back out.