Couple excerpts:
My research examines animal minds and ethics, and to me, the phrase “octopus culture” brings to mind Octopolis and Octlantis, two communities of wild octopuses in Jarvis Bay, Australia."
In Octopolis, numerous octopuses share — and fight over — a few square metres of seabed. In these watery towns, octopuses form dominance hierarchies, and they’ve started developing new behaviours: male octopuses fight over territory and, perhaps, females by throwing debris at one another and boxing.
There are many reasons to worry that an octopus farm will not be easy to manage. Unlike other farmed animals, octopuses need their space. Octopolis is already a battleground of boxing octopuses; one can only wonder what that will look like on a scale of thousands.
Octopuses are sentient — they are emotional animals that feel pain. A recent report commissioned by the department for Environment, Food & Rural Affairs in the United Kingdom reviewed the scientific evidence for pain experience in cephalopod molluscs (octopuses, squid and cuttlefish).
I would say it depends on the insect species involved. Some don't feel pain in a mammal like way, other species respond very mammal like.
From my experience, I would say that crickets can't comprehend pain in way we and other mammals do, kind of intermediate between complete robot and mammal like sentience, but spiders and moth larvae respond to "pain" in a much more mammal like way.
I'm no scientist or anything though. Just worked at an exotic pets store and looked after a tarantula for a while.