You’re free to take those off
I can’t tell you for sure which is quicker or more painless. I’m not a marine biologist and even if I were I don’t think I’d have the answer on another creature’s consciousness. Personally I think it’s really just cope and it’s splitting hairs at that point. You just need to face the fact that you’re killing and eating a living creature.
No it hasn’t been. Cockroaches, lobsters, and other arthropods have a decentralized nervous system. They have ganglia throughout their entire body instead of one centralized brain. These ganglia can react to stimuli independent of the other ones.
scientificamerican.com/…/fact-or-fiction-cockroac…

Fact or Fiction?: A Cockroach Can Live without Its Head
A nuclear war may not trouble them, but does decapitation?
Scientific AmericanWhich states are having a hard time getting food to people?
They don’t have a nervous system like vertebrates do. They can still feel pain if you slice them through the head because they have a network of ganglia throughout their body, not one centralized brain.
It doesn’t actually kill them, and it’s so small that you’re likely to miss it anyway.
None, because knowledge and the search for it is an end unto itself, so all facts are useful to learn and know.
I’d rather have holidays and birthdays fall on different days through the years.