The only animals that I consume from the ocean are the sustainable clams and scallops, and even then, I keep a weather eye on the yields from season to season. If any sort of ceph should be consumed, it should not be octopus, but squid, which seem to be filling alot of niches historically taken by fish species that have been radically depleted by overfishing. I stopped eating fish years ago, after reading the reports of wild stock declination.
Cows, on the other hand, contribute to the depletion of the ozone layer, are easily bred and maintained, and taste quite good. Growing up on a dairy farm in Minnesota, I also loathe them, and have no problem with killing them and preparing their flesh for consumption.