Let me comment on a few of the recent postings on this thread regarding blue-rings and keeping them as pets. I have studied blue-rings for several years and have kept hundreds in our lab as well as having worked with them in the field. I have also made frequent postings and have written articles warning against keeping blue-rings as pets. I will assume that the blue-rings referred to, since they showed up in the aquarium trade, were Hapalochlaena lunulata, the greater blue-ringed octopus, common in Indonesia and the Philippines. This is almost always the species available for sale.
Eight months is a long time for one of these animals to survive in captivity, although in the field they may live up to a year. Generally, only adults are shipped and they only have a few months left before they reproduce and/or die. A juvenile that is kept at a fairly low temperature and not over-fed could last several months.
H. lunulata is not normally an aggressive species and fears that they will pounce on any hand bold enough to enter their tank are greatly over-stated. They USUALLY will not attack a passing hand. However, it can happen. Animals trained to feed from a feeding stick become increasingly aggressive and will sometimes attack the stick - or a finger - that is presented in the same way as food. I have also seen females brooding eggs act very aggressively, although typically females brood in a cavity or shell and are very hesitant to come out.
Several people have referred to H. lunulata as being "shy". They are secretive and spend a lot of time in rubble or alage. However, I would not consider this species "shy". Probably because of their aposomatic coloration and toxicity, when in the open, they typically do not retreat when approached. This is one of the things that worries me about people keeping them. An animal on the side of a tank, a favorite place for H. lunulata to hang out, can be approached by a curious finger and often will allow you to prod it before moving. You or I probably would not do this without protection, but people, particularly children who don't know the danger, might. Once contact is made, these animals often escape, but they do sometimes bite.
Reference was made to H. lunulata fleeing and inking rather than attacking. Diagnostic of Hapalochlaena is that they have a reduced inksac and do not ink as part of an escape behaviour.
Finally, contributors justifying keeping them as pets often comment that blue-rings are no more venomous than other animals such as some snakes, scorpions, spiders, stonefish, etc. True. In fact, we don't even know how venomous H. lunulata is or if all animals are equally potent. The few studies conducted have almost all been done on H. maculata and H. fasciata from southern Australia. However, most people have some knowledge that snakes and spiders are dangerous and will treat them as such. Small, pretty octopus do not generally elicit the same caution in people who do not know what they are and there in lies the problem.
Roy
