How to kill a crab humanely

by Meagan

To cook crab you must buy it live. This creates a problem most home cooks don’t often face – before you cook the crab you need to kill it.

The flesh of a dead crab spoils very quickly. This means that crabs are almost unique among the animals we commonly eat, in that they must be cooked so fresh that the task of killing them comes right into the kitchen. Indeed in our world of plastic-wrapped meat most of us are disconnected from the reality of killing the animals we eat. And facing this task can be quite confronting.

There are many different ways to kill a crab. Some of the most widely used methods are forms of torture.

This page is written for those whose personal food ethics permit them to eat crab but who would prefer not to inflict unnecessary suffering.  It will show you the most humane way to kill a crab – a method which is not only endorsed by animal welfare agencies but preferred by most restaurants because it results in a tastier end product!

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Do crabs even feel pain?

Many assume that crustaceans, as invertebrates, are incapable of feeling pain.  Yet anyone who has ever seen live crabs dropped into boiling water knows that the reaction can be quite violent.  They move around vigorously as if trying it escape and “squeal” as if begging to be freed. 

We know that the “squealing” is actually the result of air escaping from their shells (crustaceans don’t have vocal chords).  And, based on the relative simplicity of the crustacean nervous system, the physical reaction was often assumed to be merely a reflex response with no feelings of pain attached.

The weight of scientific evidence now seems to suggest otherwise.  Studies at the University of Belfast on pain in prawns and crabs have provided further evidence that crustaceans do in fact feel and respond to pain.  Whatsmore, it seems that they remember pain – not only reacting instantly to it but later going to lengths to avoid the causes of past pain.

Personally I would rather err on the side of caution.  It takes no extra effort on my part to use a humane method.  And besides it’s the method used by restaurants because it tastes better!

Dungeness Crab, Pike's Place Market, Seattle, Washington, USAFresh Crab in Pike Street Market, Seattle, Washington, USADungeness Crab at Pike Place Public Market, Seattle, Washington State, USA
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My first time - a cautionary tale!

I will never forget the first time I cooked a live crab.  I’d risen bright and early to visit Billingsgate Market where I had bought up big having made promises of a seafood feast for my friends that evening.  I rode the tube home with three crabs rustling about in a plastic bag by my side.

I hadn’t thought much about the fact that they were alive and would need to be killed.  I’d always heard you ought drop them live into a pot of boiling water so assumed that’s what I would do.  Then my vegetarian friend informed me that this was the most inhumane method.  The right way to kill a crab was to simply put them in the freezer and allow them to get a little cold before entering a deep sleep from whence they die.  I saw no reason for cruelty so in the freezer it was.

An hour or two later I removed them from the freezer and left them on the bench.  You can guess what happens, right?  Within about 30 minutes I heard the rustling of plastic and realised the poor little tackers were still alive and kicking (literally)!  I sent them back into their icy den.

Crabs for Sale at Pike Place Market, Seattle, Washington, USA
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Five hours seemed enough time and I was eager to get this dish cooking.  For whatever reason I decided to start by removing the legs.  I was half way through the second crab when I detected movement in one of the last remaining legs – and my heart stopped!  I looked at the other crab – and saw beady black eyes looking up at me from a helplessly legless body.  What had I done?!  Clearly the freezer trick was only the first step in a process.  My misguided attempts to treat these crabs humanely had left me unwittingly inflicting torture!

Although I took pleasure in slurping the delicious flavours of Singapore Chilli Crab from those poor crabs’ legs later that evening, I was left somewhat traumatised by this experience (yes, clearly less so than the crab!)

I learned an important cookery lesson that day – never buy live animals unless you are ready to kill them for your meal!

Probably the most common approach to killing crab is to simply drop it into a pot of boiling water.  If crabs do indeed feel pain then this seems a particularly nasty approach.  Further, many chefs avoid this method because some crabs self-amputate their legs and claws in response to the trauma and because it tends to result in tougher crab meat.  (If you were dropped into a pot of boiling water I daresay you would tense up your muscles too!)

kill crab

Other common yet inhumane approaches include the leaving crabs in freshwater to drown, which can be a particularly slow process, and simply cutting up or removing flesh from the live animal, a self-evidently cruel method.

Step 1. Comatose the crab

The very important first step is to place the crab in the freezer for 1-2 hours.  This will desensitise the crab so that it feels no pain in the following procedure.

Step 2. Ensure the crab is unconscious
Kill crabkill crab humanely
Step 3. Destroy the crab's nerve centres
kill crabkill crab humanely

When you are sure the crab is desensitised you need to identify the crab’s nerve centres.  Turn the crab onto its back.  At the front you will find a shallow depression near to the crab's mouth (but on the underside).  This is the front nerve centre.  Lift the tail flap and you will see a tender area or even a small hole in the shell.  This is the hind nerve centre.  Pierce the hind nerve centre with a knife until you feel it hit the shell on the other side.  Then quickly revert to the front nerve centre and do the same.

Remove the crab from the freezer and check for any signs of consciousness.

Begin by turning the crab over and tapping on the shell while checking for any eye reactions.  Then touch the crab around the mouth parts while checking for any reactions or movement in this area.

If you see any reaction at all, or if you feel any resistance as you are handling the crab then place the crab back in the freezer for another 30-60 minutes.

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Smiling Crab on Beach with Knife and Fork
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Updated: 04/05/2012, Meagan
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LianaC on 06/25/2016

In response to someone else who posted here about steaming being a humane method: I have my doubts. I steamed some crab last week, and when they went into the pot, they scrambled about, and tried to climb out of the pot by scurrying up the rounded edges of the steamer. It was quite sad to see, and I deeply regretted not researching beforehand for a more humane method of dispatching them. If it's true that they cannot sense heat (which I doubt is true), then they wouldn't have reacted to it like that, since they were very calm when they went into the pot (before it warmed up.)

Thanks so much for this blog post. I've read elsewhere that destroying the two nerve centers is a more humane way to kill crabs, and I'll be trying it tonight.

Chef Patrick on 02/28/2015

IF you are concerned about your dining guests eating tough crab meat, wouldn't you freeze the crabs for 5 to 6 hours first, and then de-nerve them?

Makes sense to me, and I have always tried my bst to create the best tasting dishes!
Same as with all animals, we do not want the muscles to be infused with all the chemicals of fear, like adrenaline, and muscle contractants! Many of us also prefer spear fished marine creatures, which taste better than those taken in nets or on hooked lines!

frankbeswick on 07/12/2014

Excellent article.A combination of sensitivity and pragmatism. I note that you have written 9 articles in three years.That's not much for a good writer. Let us have more from you. You are good enough.

Gerald Vegas on 07/12/2014

Cooked my first crab today at the ripe old age of 41. Had done a lot of research on the net if the most humane way to kill it as this was always the step that put me off.

One hour in the freezer and turned on its back it seemed pretty dead, but got a shock when i peeled back the tail for the knife plunge as it started moving. I am afraid i went ahead and put it out of its misery with a knife to the hole under the tail. Then it was straight to the pot of readily boiling water... It moved a bit but stopped pretty quickly..

Next one will be freezer for at least two hours and then severing the two nervous centres as you describe. Many thanks for your post!

The killing part isn't pleasant but in the other hand as a meat eater i sure i gave the crab much more respect and thought about its demise than all the processed shrink wrapped meat i buy in the supermarket.

Plus it tasted absolutely fantastic and would eat in preference to meat any day..

Lelele on 07/18/2013

wow, my mom always had steamed them alive... i feel so guilty now! but my mom steamed them in one piece. i read somewhere if you steam/boil them they instantly die? i love crab, but knowing society hates people like me who just cook the crab live, i feel kinda sad. but next time, i'll try to convince my mom to freeze them first :) thank you!

saib on 06/27/2012

amazing page.. a complete eye-opener..
i think choosing the most considerate method for turning a living animal into a food product is important. and keeping this as the top reasons, we can also think secondarily about the meat losing its quality with the boiling water method.

[and by the way, your page made me read in detail about crabs - crustaceans - arthropods - exoskeletons - fossils and finally pangaea; can you believe it!?]

John on 06/03/2012

I like to remove the crabs eyes while it is alive and then pull the legs off one by one until it's just a pile of shells, then I drop it in the boiling water to finish it off. I guess I am a crab genitorturer.

Meagan on 04/18/2012

RainDefence I did wonder if I should put a rating or warning of graphic content at the top of the page!

And to those of you who don't think you could kill one, I do understand. I confess that I felt more than a little discomfort about publishing an article entitled "How to kill...". I don't think it feels entirely comfortable to kill a living being of any kind (oh except mosquitoes, I do that without even thinking!)

Thank you for your comments.

Meagan on 04/12/2012

Great question Sam! Many crabs actually die in the freezer - but not all and as far as I know there is no way to tell whether they are dead or just comatosed so you always need to follow through with the next step. Presumably they would die very quickly after being thrown into boiling water. The RSPCA and other humane societies state that rapid destruction of the nerve centres is the only humane method apart from electro-stunning (which requires a specialised machine). I can only assume that this method is more instant than boiling water - though the time difference may be negligible.

Sam on 04/11/2012

I am wondering, would it work to first put the crab in the freezer for several hours (six or more) and then drop it directly into boiling water? Would save the operation and I guess / assume that they are cooked before they come to their senses again? Or am I wrong?

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