The entrails of octopus, for example, can be used in bird feed manufacture because of their high protein content, and the enzymes derived from the mollusc’s liver are used in the industrial manufacture of skin-care creams.
If you are going to raise an animal for food, not wasting the parts is a good thing in my book. Cows and pigs are more intelligent than cephs and we typically (I know some people aren't but globally speaking, we are meat eaters) accept that an animal dies to feed us. Each of us has a line we draw somewhere and it is arbitrary depending upon our upbringing, body requirements and stages of mental outlook.
A lot of folks like to eat octo, and I dont think that will change. That being said, farm raising them, I think, is better than catching the wild ones. I personally think they taste like a rubberband but to each his own. I have to agree with D, since we are going to eat them we may as well put the leftovers to good use.
Since I personally have a major problem with the methods used in intensive chicken farming, horrible treatment of the animals and devastaing effects on the local environment, I'm going to have to side with Ob on this one. The pfiesteria problems in the Chesapeake Bay were caused by those farming techniques.
Just to clarify, I have no issues with eating fish, meat (octopus, "the chicken of the sea") and certainly not with "using" as much of the animals we kill as we can, but I do have big issues with intensive farming. This includes intensive octopus farming.
Just something funny when i first tried eating an octo. My family and i went to a fancy restaurant and one of the appetizers was calamari(i thought that was just squid) and i am fine with eating squid. The plate came and it had the normal looking calamari. I saw this odd looking shape. It was literally a tiny octo that was deep fried. the mantle was about 1/2 in and they had the legs curled so it looked more appetizing. The funny thing is that was the exact same day i got a new octo.