# Deadly Shellfish **URL:** \ **Category:** Factual Questions\ **Created:** [March 11, 2002, 9:54pm UTC](https://boards.straightdope.com/t/deadly-shellfish/97697 "2002-03-11T21:54:43Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [March 11, 2002, 9:54pm UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/1 "2002-03-11T21:54:43Z")
Lobsters have to be eaten freshly cooked because a toxin develops once they are dead. What is the nature of this toxin and how does it develop? What about related shellfish, such as crayfish? I note that when crayfish (or crawlfish) are served in restaurants, only the “tips” are served. What part of the crayfish is the “tip”? Does the rest of the crayfish develop the same toxin? In addition, what about bivalves, such as clams, mussels, etc.? Those are served whole and not necessarily fresh, so the toxin apparently is not found in them. Let’s see. That’s five questions. What’s my limit? Did you say six?😃 ---
**Author:** ![Lisa\_Ann](https://avatars.discourse-cdn.com/v4/letter/l/bc79bd/32.png) [@Lisa\_Ann](https://boards.straightdope.com/u/Lisa_Ann)\ **Post date:** [March 11, 2002, 10:46pm UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/2 "2002-03-11T22:46:29Z")
Craw **l** fish or crawfish? 🙂 I found this link to Canada’s Red Tide: http://www.pac.dfo-mpo.gc.ca/ops/fm/shellfish/Biotoxins/PSP.htm > [@](#): > > Agent: Paralytic Shellfish Poison (PSP)Classification: Marine Biotoxin > > Fish Products Most Affected: > > Clams; Mussels; Whelks, Moon-Shells and Dogwinkles; Oysters; Whole Scallops; Crabs and Lobster hepatopancreas (tomalley). > > The majority of the toxin within shellfish is normally found within the digestive gland. > > Properties of the Agent Relative to the Food and Illness: > > Paralytic shellfish poisoning (PSP) results from eating shellfish which have fed upon toxic dinoflagellates, a type of one celled microscopic organism which forms an important part of the ocean plankton. During ‘blooms’, that is rises in the number and concentration of phytoplankton, filter-feeding shellfish such as clams and mussels accumulate the poisons from the dinoflagellates when feeding on them. The uptake and clearance rates of the toxins vary widely with species and are influenced by a number of factors. However, it should be noted that some species (e.g. butter clams) can retain the toxins for long periods after the bloom has finished. > > PSP has occurred world-wide. ---
**Author:** ![mmmiiikkkeee](https://avatars.discourse-cdn.com/v4/letter/m/edb3f5/32.png) [@mmmiiikkkeee](https://boards.straightdope.com/u/mmmiiikkkeee)\ **Post date:** [March 12, 2002, 6:19am UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/3 "2002-03-12T06:19:12Z")
I’ve never heard of a toxin building up in lobster after it’s cooked, but then again I’m too poor to buy lobster anyway so I may not be in the loop. AFAIK you won’t want to eat week-old cooked lobster any more than you’d want to eat ANY week-old refrigerated seafood; it tends to go bad (or at least smell that way) quicker than say chicken or turkey. But no special toxins that I know of other than the usual crap that breeds on dead meat in the fridge… you can buy lobster that’s long dead under cellephane in the stores too, so I think they deteriorate the same way other meat does. Like the previous link said, psp poisoning found in shellfish, usually filter feeders, has nothing to do with the critters themselves being dead or alive - it’s a toxic algae they suck in and retain for a long time. This algae doesn’t kill them, but it can sometimes take a long time for them to get rid of it, perhaps years… which is partly why some beaches get closed for extended periods of time for shellfish harvesting. If you drank enough of the seawater with red tide cells in it, you’d die from that too (although the salt would do you in long beforehand) They can make you sick in other ways depending on what they’ve eaten… on polluted beaches with high fecal colliform counts, they of course suck the stuff up, get dug up by us, and dumped onto your plate 2 days later. And you guessed it; you’re swallowing tiney amounts of raw sewage and bacteria still inside their little tummies. They can be depurated to get rid of bacteria, or cooked really well, but red tide doesn’t cook out. As far as shellfish go, it’s more important what happened to them in the water than what happens once they hit the packing plant or refigerator. ---
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [March 12, 2002, 5:10pm UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/4 "2002-03-12T17:10:09Z")
If you order lobster in a restaurant, the lobster is always alive until after you order it. It must be eaten freshly cooked. I’ve heard it’s the same with crabs. They’re boiled alive and eaten fresh. I don’t know about crayfish, but all they ever serve in restaurants are crayfish tips, whatever they are. OTOH, you can buy crab meat in the shell at a restaurant, which are not freshly killed. In fact, crabs served in a restaurant are not freshly killed, but lobsters are. Nonetheless, I’ve heard that if you catch crabs, you have to eat them immediately, right after boiling them. 😕 ---
**Author:** ![Ike\_Witt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ike_witt/32/283_2.png) [@Ike\_Witt](https://boards.straightdope.com/u/Ike_Witt)\ **Post date:** [March 12, 2002, 5:21pm UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/5 "2002-03-12T17:21:13Z")
I don’t know where you guys are eating your crawfish, but around here the whole damn thing is served. How can you suck the head if you are only getting the ‘tip’ (I assume you mean the tail)? ---
**Author:** ![dwyr](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dwyr/32/363_2.png) [@dwyr](https://boards.straightdope.com/u/dwyr)\ **Post date:** [March 13, 2002, 1:54am UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/6 "2002-03-13T01:54:55Z")
I seem to remember that on an episode of “Good Eats”, Alton Brown said that as soon as a lobster was killed, digestive enzymes started working and would soon turn the meat to mush and that’s why they have to be cooked immediately. Heat from cooking would destroy the enzyme’s activity. I don’t know about crabs and crawfish though. But definitely not a toxin, the enzymes just make the meat very unpalatable. ---
**Author:** ![Motog](https://avatars.discourse-cdn.com/v4/letter/m/85e7bf/32.png) [@Motog](https://boards.straightdope.com/u/Motog)\ **Post date:** [March 13, 2002, 2:26am UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/7 "2002-03-13T02:26:58Z")
Only toxic after they’re dead? pshawww! Here in Australia - where most animals, except a few of the sheep, are deadly - we’ve got cone shellfish that can deliver a neurotoxin through a small tooth. We also have the blue ring octopus that can deliver a neuromuscular toxin that causes respiratory paralysis and don’t even get me started on sea snakes! ---
**Author:** ![jb\_farley](https://avatars.discourse-cdn.com/v4/letter/j/9d8465/32.png) [@jb\_farley](https://boards.straightdope.com/u/jb_farley)\ **Post date:** [August 13, 2002, 9:43am UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/8 "2002-08-13T09:43:43Z")
well, this is great! i was searching for threads on inedible crab parts (last time i had crab, i discovered what my friend called the gills- dark greenish, and with a texture like an orange- yummy! (YMMV) anyway, another friend later told me the gills are poisonous). searching for that made me think of a GQ i’ve been meaning to ask for a while. this was my only search result for the former, and what do you know? OP’s same as my original question. but it doesn’t seem to have been answered. i’m not too sure if i should bump this one, or write a new GQ, so i will err on the side of caution, and bump this. i guess my GQ would have been- i’ve been told crabs (and lobster) _must_ be cooked before they die. unlike most everything else, which tends to be killed first, then eaten (notable exception- foods which were never alive in the first place- such as eggs and that soil that picish anemic african women ate). an explanation was never given. i had always thought poison, or infection, or something. what is the straight dope? can crabs be cooked whenever? if not, why not? jb ---
**Author:** ![clairobscur](https://avatars.discourse-cdn.com/v4/letter/c/839c29/32.png) [@clairobscur](https://boards.straightdope.com/u/clairobscur)\ **Post date:** [August 13, 2002, 10:38am UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/9 "2002-08-13T10:38:11Z")
I always assumed that shellfish were cooked alive because there wasn’t any way to conveniently kill the critter (you can’t slice its throat nor break its neck, like you would do with other animals, and it doesn’t die just because it’s out of the water, like fish, either), so the simplest way is to throw it directly in the pan/boiling water. Never considered it could be related to them been poisonous or toxic… ---
**Author:** ![Stana\_Claus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stana_claus/32/13874_2.png) [@Stana\_Claus](https://boards.straightdope.com/u/Stana_Claus)\ **Post date:** [August 13, 2002, 1:31pm UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/10 "2002-08-13T13:31:59Z")
Most of my experience related to this topic is with crawfish, but I would think it applies equally to lobsters and crabs. At a crawfish boil, you want to select and eat only the crawfish with tightly curled tails. A tightly curled tail indicates the crawfish was alive when it went into the pot. A straight tail indicates the crawfish was dead before it was cooked. The problem with dead crawfish is you don’t know how long it had been dead before going into the pot. All creatures, once dead, begin to decompose unless preserved in some manner. Past a certain point, any decomposing flesh consumed will make you violently ill unless, of course you are a vulture or some other specially adapted carion eater. Shellfish decompose quickly upon death and reach an illness producing state post haste. Therefore, rather than take chances on just how long our shellfish has been dead and whether or not it is still safe to eat, if you throw it in the pot while it’s still kicking, you are pretty certain it’s at least fresh. As for toxins that may have been absorbed from the water they were in, well, that’s a whole 'nuther matter. As to the OP, I don’t know what specific toxins are created by decomposing flesh. I do know that different creatures decompose at different rates in different environments (you can age beef before cooking, but only if properly handled) and most shellfish reach the point of inedibility pretty quickly after death. ---
**Author:** ![jb\_farley](https://avatars.discourse-cdn.com/v4/letter/j/9d8465/32.png) [@jb\_farley](https://boards.straightdope.com/u/jb_farley)\ **Post date:** [August 13, 2002, 1:39pm UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/11 "2002-08-13T13:39:30Z")
to clarify, i was informed early and often that if a crab died at any point (and for any reason) before cooking, said crab could kill you. jb ---
**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\ **Post date:** [August 13, 2002, 3:58pm UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/12 "2002-08-13T15:58:13Z")
> [@](#): > > \*Originally posted by clairobscur \* > \*\*I always assumed that shellfish were cooked alive because there wasn’t any way to conveniently kill the critter (you can’t slice its throat nor break its neck, like you would do with other animals, and it doesn’t die just because it’s out of the water, like fish, either), so the simplest way is to throw it directly in the pan/boiling water. > > Never considered it could be related to them been poisonous or toxic… \*\* Cookbook claims you can kill the critter by stabbing it between the eyes with a sharp knife, if you don’t like the idea of boiling it alive. I seem to recall another source suggesting a skewer in a strategic spot. I’m sure it would be more convenient to sell them already dead if it was acceptable. ---
**Author:** ![clairobscur](https://avatars.discourse-cdn.com/v4/letter/c/839c29/32.png) [@clairobscur](https://boards.straightdope.com/u/clairobscur)\ **Post date:** [August 13, 2002, 5:14pm UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/13 "2002-08-13T17:14:11Z")
> [@](#): > > \*Originally posted by yabob \* > \*\* > Cookbook claims you can kill the critter by stabbing it between the eyes with a sharp knife, if you don’t like the idea of boiling it alive. I seem to recall another source suggesting a skewer in a strategic spot. I’m sure it would be more convenient to sell them already dead if it was acceptable. \*\* Yes, but only recently people began to worry about whether their food was killed in a cruel way or not. I would suspect that since there’s no real point in killing the crab/lobster (it can’t flee, you don’t need to skin it, etc…), people just used to cook it alive, and still do so because it’s the tradition. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [August 13, 2002, 6:15pm UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/14 "2002-08-13T18:15:59Z")
I seem to recall hearing that male crabs were stabbed in the back with an ice pick to keep them from tearing each other apart while in the bucket before being cooked. Does anyone know about this? If it is done, does it kill them or just disable them? ---
**Author:** ![dwyr](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dwyr/32/363_2.png) [@dwyr](https://boards.straightdope.com/u/dwyr)\ **Post date:** [August 13, 2002, 11:50pm UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/15 "2002-08-13T23:50:09Z")
Well, a quick search shows that most sources say the main reason to cook lobster while alive is that they quickly go bad as bacteria rapidly multiply, especially since lobsters are scavengers and eat already dead or decaying materials. But if kept sufficiently cold they can be kept for some hours after death and still be safe to eat. [Boston Globe Archives](http://www.boston.com/globe/search/stories/health/how_and_why/052096_1.htm) [USA Today](http://www.usatoday.com/news/science/wonderquest/2001-09-19-lobsters.htm) [Maine Lobster Co.](http://www.mainelobsterco.com/faqscook.htm) I don’t know but would imagine that similar rules apply to other shellfish such as crabs which also seem to be highly perishable. ---
**Author:** ![mmmiiikkkeee](https://avatars.discourse-cdn.com/v4/letter/m/edb3f5/32.png) [@mmmiiikkkeee](https://boards.straightdope.com/u/mmmiiikkkeee)\ **Post date:** [August 14, 2002, 1:32am UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/16 "2002-08-14T01:32:22Z")
I’ve seen (and bought, then eaten) crabs under cellephane in the supermarket sans getting sick, and they were most definately dead. I beleive the reason most people cook them live is due to the rate at which they go bad after dying; although they do have a short “shelf life” after the fact if kept cold enough. Add to that the freshness/gourmet aspect - most of us don’t eat lobster like we do cereal, so they few times a year we spend the money we want the best/freshest we can get, which is almost always the “still wiggling” stage. And since it’s usually a rare occurance, we just do what everyone else suggests rather than taking a chance and experimenting. ---
**Author:** ![jb\_farley](https://avatars.discourse-cdn.com/v4/letter/j/9d8465/32.png) [@jb\_farley](https://boards.straightdope.com/u/jb_farley)\ **Post date:** [August 15, 2002, 1:06am UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/17 "2002-08-15T01:06:48Z")
**mmmiiikkkeee** , were the crabs in cellophane pre-cooked? cuz i’ve seen shellfish for sale all the time, but they appear to have been already cooked (mussels open, etc). jb ---
**Author:** ![reprise](https://avatars.discourse-cdn.com/v4/letter/r/ea666f/32.png) [@reprise](https://boards.straightdope.com/u/reprise)\ **Post date:** [August 15, 2002, 1:16am UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/18 "2002-08-15T01:16:13Z")
I’d always thought that the reason we cooked yabbies and prawns live (rather than drowning or otherwise killing them first) was because the stress caused them to empty their alimentary tract. This is very probably an urban legend as it’s something I’ve “known” since childhood but am unable to recall it coming from any authoritative source. ---
**Author:** ![jb\_farley](https://avatars.discourse-cdn.com/v4/letter/j/9d8465/32.png) [@jb\_farley](https://boards.straightdope.com/u/jb_farley)\ **Post date:** [August 15, 2002, 5:56am UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/19 "2002-08-15T05:56:24Z")
**reprise** , that’s not too bad of an idea. but do smaller animals excrete in the same way we do? i’ve always thought that we shit and piss in terror because of a slackening of muscle tone. same reason people void upon death. jb ---
**Author:** ![Deadly\_Nightlight](https://avatars.discourse-cdn.com/v4/letter/d/6a8cbe/32.png) [@Deadly\_Nightlight](https://boards.straightdope.com/u/Deadly_Nightlight)\ **Post date:** [August 15, 2002, 8:22am UTC](https://boards.straightdope.com/t/deadly-shellfish/97697/20 "2002-08-15T08:22:22Z")
nothing new to add except I like deadly shellfish better than the name i have now 😃