Crabs are crustaceans.
Female crabs are called “hens”; male crabs are called “cocks.” Males are very narrow tails and larger claws. Females have broader tails that are somewhat heart-shaped.
Which species of crab is popular where depends basically on what’s available there: in Europe, it’s the spider and brown crabs; in North America, on the Atlantic Coast, it’s blue crabs, and on the Pacific coast, dungeness crabs. In the UK, the most commonly sold crab is the brown one, though the spider crab started to become popular in the early 2000s.
Dungeness crabs and blue crabs are two examples of crabs that have edible meat in both their bodies and their claws, but not all crabs do.
Light and dark crabmeat
Just as there is light and dark meat on a turkey, there is light and dark meat in a crab. In general, their claws have white, sweet flesh, and their bodies have brown, rich flesh. Males have more white meat because they have larger claws, but even still, a white crab will be about three-quarters dark meat. Most recipes will ask for the white meat, which is flaky and mild-tasting; the dark meat is sweeter and coarser. You can use the dark meat in soups, but usually to get enough white meat for a recipe you need to buy it already separately plucked out. Fresh crab meat sold in fish counters is sometimes pasteurized to give it a better shelf life.
Crabs shed their exterior shells as they grow, and develop new ones.
Boyce Rensberger, writing for the Washington Post, says:
“Molting, which all crabs do many times, is necessary for growth. Having only part of its skeleton inside, the crab body gains greater structural strength from a rigid, external skeleton. This ‘exoskeleton’ has one drawback — it can’t grow. So the shell is shed periodically, and the crab immediately gulps water to make its body swell before the soft, new shell underneath hardens, a process that takes only a few hours. Later, as the crab’s tissues grow, they displace the water stored throughout the body, filling the shell. The molt is always a dangerous time for a crab. Without a hard shell, it is defenseless and easily killed by predators, especially other crabs.” Rensberger, Boyce. The Blue Crab’s Life and Death. Washington, DC: The Washington Post. 14 August 1996.
Understanding that moulting happens, and particularly the water intake part, can help you select better crabs to buy (see Buying Crabs below.)
Don’t buy any crabs that don’t show any signs of life (though they won’t be all that energetic if refrigerated, they should still make some kind of attempt to move their claws if poked at.)
Though this may seem obvious, the larger the crab, the more meat there will be on it, and the less fiddly it will be to get that meat out of the body.
Try to avoid ones that have recently moulted (shed their old shell.) If a lot of water comes out of the crabs when you crack them open after cooking, what you were sold is ones that recently moulted and got new shells. They haven’t yet grown fully into their new shells, so there will be a lot of water inside them. If the bottom of the crab is white, chances are their shells are brand new. Look for ones that are stained or rusty-looking on the bottom.
Crabs should not smell fishy at all.
Dungeness crabs and blue crabs have edible meat in both their bodies and claws. To open a cooked blue crab or dungeness crab, or other type of crab that has edible body meat, break off and set aside all the limbs, flip the body upside down, and use a knife to pry off the shell in the centre of its bottom (called the “apron” flap.)
Turn it right side up, lift off the top shell. Discard both shells, of course (or, if you are doing this in the kitchen, you can freeze them for making a stock later.)
You will see a membrane covering the crabmeat, and on top of that some body parts (lungs and other things.) The grey, furry-looking things are the lungs (sometimes called “dead men’s fingers”.)
The stomach is a grey sack just below the head. Scrape the lungs and stomach off, along with other innards and discard (they are not poisonous, but they are indigestible.) Then pull the halves apart, remove the gills and take out the dark meat. There’s a bony bit in the centre.
Crack the legs and the claws, and use a skewer to get the white meat out of them.
Alaska King Crab
Alaska king crabs gave edible meat in claws and legs.
Break off the claws and legs. Use your knife handle to crack them open so you can get at the meat inside them.
Discard the body.
Stone crabs have edible meat in their claws only.
Break off the claws. Use your knife handle to crack them open so you can get at the meat inside them.
Discard the body and legs.
Lump crabmeat is large pieces of crab from any type of crab that can be used for “presentation”, such as in salads, open-face sandwiches, pastas, etc.
You may see it in tubs in grocery store chillers.
Backfin crabmeat is smaller, broken flakes or chunks of crab meat that can be used in sauces, salads, dips, fried rice, crab cakes, etc.
It often comes tinned.
Crab mustard (aka tomalley)
Many people love the strong-tasting, yellow stuff inside a crab. It is a gland that branches out on both sides of the crab’s stomach to function as its liver and pancreas. In areas where the water may be doubtful, it’s best not to eat this, as part of its function is to filter impurities, so any chemical contaminants will be concentrated in the mustard.
Still, aficionados gauge their entire cooking of the crab on what state they want the mustard in — neither hard nor runny, they feel it is best cooked just until it is like a soft-boiled egg.
Allow about 500 g (1 pound) of unshelled crab per person. In the summer, ask your seafood dealer for female crabs; in the spring, ask for male crabs.
Before cooking crabs, let them come to room temperature so that you can see if they are alive or not. Discard any dead ones.
Crabs may “drop” their claws in an attempt to escape while being cooked. To prevent this, either drop them in ice water a few minutes before cooking to stun them, or kill them by poking an ice pick or a nut pick through their heads (flip the crab upside down — stab them through the shell just below their mouth.) Alternatively, you can pop the live crabs in the freezer until there is no movement from them when poked. This may take up to 1 1/2 hours, but don’t leave them in there longer than 2 hours. This also is considered a “humane” way of killing them, because — or so the theory goes — they painlessly slide into unconsciousness. When removing them from the freezer, bear in mind that their claws will now be very brittle, so be careful not to knock them off.
If you have kitchen scales, they’ll come in handy now. Weigh each crab, and plan to cook according to the following guide:
- Weight up to 500 g (1 pound): 15 minutes;
- Weight up to 1 kg (2 pounds): 20 minutes;
- Weight up to 1.5 kg (3 pounds): 25 minutes;
- Any weight over that, 30 minutes.
Bring a large pot of water to the boil. Add about 1 teaspoon of salt per litre / quart of water.
Cook the crabs until their shells turn red and the meat inside is white. A crab’s shell turns red when cooked because the heat destroys all the other pigments except the red. The red pigment, which is called astaxanthin, is heat stable, and comes to prominence when the others disappear.
1 cup of crab meat in lumps = 4 oz / 125 g
Store fresh crabs in fridge wrapped in a wet tea towel and use within 24 hours.
Literature & Lore
Clementine Paddleford, a famous food writer, wrote this for Gourmet Magazine in 1944:
“Cooked crab meat comes in two forms, washed and unwashed, and therein lies that little difference in flavor. Which of the two styles you prefer is merely a matter of taste. Washing removes the ‘fat,’ or immature roe, and gives the whiter meat. Florida supplies 50 per cent of the crab meat on the Eastern markets, and sends the washed only, for the good business reason that the average shopper prefers white meat to ivory-toned. But there is an exclusive group of crab meat epicures who, breathing the rarefied Olympic air of gourmetdom, are willing to pay a dividend for the meat unwashed, claiming it to be richer and more flavorful. Maryland, North Carolina, Virginia send the bulk of the meal unwashed. And no doubt about it, the flavor is more staunchly crab. But you may prefer the meat of greater whiteness, the more delicate taste.” Paddleford, Clementine (1898 – 1967). Food Flashes Column. Gourmet Magazine. August 1944.