There happen to be two main criteria that most ethicists agree on for determining whether a living creature has the capacity to suffer and so has genuine interests that it may or may not be our moral duty to consider.16 One is how much of the neurological hardware required for pain-experience the animal comes equipped with—nociceptors, prostaglandins, neuronal opioid receptors, etc. The other criterion is whether the animal demonstrates behavior associated with pain. And it takes a lot of intellectual gymnastics and behaviorist hairsplitting not to see struggling, thrashing, and lid-clattering as just such pain-behavior. According to marine zoologists, it usually takes lobsters between 35 and 45 seconds to die in boiling water. (No source I could find talked about how long it takes them to die in superheated steam; one rather hopes it’s faster.)
There are, of course, other fairly common ways to kill your lobster on-site and so achieve maximum freshness. Some cooks’ practice is to drive a sharp heavy knife point-first into a spot just above the midpoint between the lobster’s eyestalks (more or less where the Third Eye is in human foreheads). This is alleged either to kill the lobster instantly or to render it insensate—and is said at least to eliminate the cowardice involved in throwing a creature into boiling water and then fleeing the room. As far as I can tell from talking to proponents of the knife-in-the-head method, the idea is that it’s more violent but ultimately more merciful, plus that a willingness to exert personal agency and accept responsibility for stabbing the lobster’s head honors the lobster somehow and entitles one to eat it. (There’s often a vague sort of Native American spirituality-of-the-hunt flavor to pro-knife arguments.) But the problem with the knife method is basic biology: Lobsters’ nervous systems operate off not one but several ganglia, a.k.a. nerve bundles, which are sort of wired in series and distributed all along the lobster’s underside, from stem to stern. And disabling only the frontal ganglion does not normally result in quick death or unconsciousness. Another alternative is to put the lobster in cold salt water and then very slowly bring it up to a full boil. Cooks who advocate this method are going mostly on the analogy to a frog, which can supposedly be kept from jumping out of a boiling pot by heating the water incrementally. In order to save a lot of research-summarizing, I’ll simply assure you that the analogy between frogs and lobsters turns out not to hold.
Ultimately, the only certain virtues of the home-lobotomy and slow-heating methods are comparative, because there are even worse/crueler ways people prepare lobster. Time-thrifty cooks sometimes microwave them alive (usually after poking several extra vent holes in the carapace, which is a precaution most shellfish-microwavers learn about the hard way). Live dismemberment, on the other hand, is big in Europe: Some chefs cut the lobster in half before cooking; others like to tear off the claws and tail and toss only these parts in the pot.
And there’s more unhappy news respecting suffering-criterion number one. Lobsters don’t have much in the way of eyesight or hearing, but they do have an exquisite tactile sense, one facilitated by hundreds of thousands of tiny hairs that protrude through their carapace. “Thus,” in the words of T.M. Prudden’s industry classic About Lobster, “it is that although encased in what seems a solid, impenetrable armor, the lobster can receive stimuli and impressions from without as readily as if it possessed a soft and delicate skin.” And lobsters do have nociceptors,17 as well as invertebrate versions of the prostaglandins and major neurotransmitters via which our own brains register pain.
Lobsters do not, on the other hand, appear to have the equipment for making or absorbing natural opioids like endorphins and enkephalins, which are what more advanced nervous systems use to try to handle intense pain. From this fact, though, one could conclude either that lobsters are maybe even more vulnerable to pain, since they lack mammalian nervous systems’ built-in analgesia, or, instead, that the absence of natural opioids implies an absence of the really intense pain-sensations that natural opioids are designed to mitigate. I for one can detect a marked upswing in mood as I contemplate this latter possibility: It could be that their lack of endorphin/enkephalin hardware means that lobsters’ raw subjective experience of pain is so radically different from mammals’ that it may not even deserve the term pain. Perhaps lobsters are more like those frontal-lobotomy patients one reads about who report experiencing pain in a totally different way than you and I. These patients evidently do feel physical pain, neurologically speaking, but don’t dislike it—though neither do they like it; it’s more that they feel it but don’t feel anything about it—the point being that the pain is not distressing to them or something they want to get away from. Maybe lobsters, who are also without frontal lobes, are detached from the neurological-registration-of-injury-or-hazard we call pain in just the same way. There is, after all, a difference between (1) pain as a purely neurological event, and (2) actual suffering, which seems crucially to involve an emotional component, an awareness of pain as unpleasant, as something to fear/dislike/want to avoid.