From tiny Oyster Crabs that make their homes in live oysters to the world’s heaviest crab, the Giant Crab, found in our southern waters, there are well over 1,000 species of Decapoda reptantia (‘ten footed crawlers” or Crabs) worldwide. They are found in a wide range of marine habitats and vary greatly in size and appearance, but many have delicious soft, moist, sweet flesh and are less expensive than other comparable shellfish.[no_toc]
Most edible crabs in Australia belong to the “swimmer” family, and can be identified by flat paddles on the end of their back legs. Only a few species are targeted around Australia, with the rest being bycatch. The three main species seen in Australia are:
Blue Swimmer Crabs (Portunus pelagicus), distinctive for the mottled bright blue to purple of the males” shells (the females tend to be more mottled brown), are caught year round with peaks from November to April. They weigh an average of 200-300g and, like all crustacea, turn orange when cooked. They are one of the few crabs not sold live, but cooked or green (uncooked), as they don’t survive well once captured. They yield about 35% meat, are medium priced and have a mild, sweet, nutty flavour.
Mud Crabs, also swimmer crabs, are found mainly on the muddy bottoms of shallow coastal mangroves. A number of closely related Mud Crabs, are differentiated by colour, but the Giant Mud Crab (Scylla serrata), with its dark blue-green to mottled brown shell, is by far the major species in Australia. Most common in Queensland, where only the males are caught, they are available year round. Supply peaks from January to April in Queensland and NSW and from May to August in the NT. They have large front legs and developed claws and generally weigh 500g-1kg. They”re mostly sold live (as they can live out of water for days) but are also available cooked. It is best not to buy dead uncooked Mud Crabs as it’s difficult to determine their quality. They yield about 25% meat, largely from the front claws, and are high priced with sweet flesh that has a slightly stronger flavour and firmer texture than that of other crabs.
Spanner Crabs (Ranina ranina), with their long, almost goblet-shaped, bright orange shells (even when uncooked) and spanner-shaped front claws, are quite distinctive. Usually found close inshore, often buried in sand, they are mainly fished off NSW and Queensland from January to October, peaking from July to October with the fishery closed for most of December. They average about 400g and are usually sold cooked, although they can occasionally be found live. Although they only yield 25% meat, they are lower priced than other crabs and some chefs prefer their distinctive flavour.
Other Australian Crabs
(Pseudocarcinus gigas), the world’s heaviest crabs, are found only in Australia’s southern waters. They have an almost triangular-shaped orange-red shell with cream flecks and very developed front legs and claws with black tips. Very popular in the 1990s, especially in Chinese restaurants where they are often still seen, there is increasing realisation that the fishery for these slow growing, long living creatures needs to be carefully managed. There is some experimental aquaculture in Tasmania. Incorrectly called King Crab in the past, they are not related to the King Crabs of Alaska. Sometimes known as the Tasmanian giant crab, giant deep-water crab, giant southern crab or queen crab.
(Chaceon bicolor) are large chalky-white crabs of increasing importance, caught commercially off WA. Previously known as Snow Crabs, they are unrelated to the true Snow Crabs of the northern hemisphere. Crystal Crab has a firm textured, succulent white flesh with a distinctive sweet taste. In fact the Australian crystal crab is considered the best tasting crab of all crab species around the world. Crystal Crab is very adaptable for many western and eastern cuisine presentations.
(Hypothalassia armata) have a mottled pale brown to cream shell with spiny edges, black tips on their claws and spines along their legs. The spiny crab, also known as the champagne crab, are caught in very small quantities and are primarily exported to the Chinese market. They are caught in the southern waters of Western Australia at depths between 145 to 200 metres in water temperatures of 16.1–17.1°C.
Four other swimmer crabs are caught as a bycatch of Blue Swimmer Crab fishing: Three-spotted Crabs (Portunus sanguinolentus) named for the three distinct white-edged purple/red spots towards the back of their greenish-yellow shells. Hairyback Crabs (Charybdis natator) with a covering of fine hairs all over their shells. Sand Crabs (Ovalipes australiensis) with pale blue/grey shells and two prominent red spots at the back of their shells. Coral Crabs (Charybdis feriata) with distinctive vertical dark brown to purple stripes on their shells.
Regardless of the type of crab, look for ones which feel heavy for their size and have their legs and claws intact. With dead crabs, if possible, give them a gentle shake to ensure there’s no sound of sloshing water. Live crabs should be vigorous. Females with eggs are always protected, and in Queensland catching any female crabs is prohibited (except for Spanner Crabs without eggs).
The RSPCA has guidelines for the humane killing of all crustaceans. The most acceptable, and easiest, method is to chill them in the freezer for about 45 minutes until they become insensible (but not long enough to freeze them). Once chilled, they should be killed promptly by splitting them in half or dropping them into rapidly boiling water.
Keep live crabs in a cool place with a damp cloth over the container, ensuring that the cloth remains damp. Cooked or dead crabs should be wrapped in plastic wrap or foil and stored in an airtight container in the fridge for up to 3 days or frozen, at -18ºC or lower, for up to 3 months. Picked crab-meat can be stored in the same way.
Crabs can be steamed, poached, deep-fried, stir-fried, pan-fried, grilled or barbecued. Don’t try to pick raw crab-meat, it’s almost impossible as the flesh is too watery.
If you need crab-meat, place chilled whole crabs in a large pot of rapidly boiling water, that has been well salted (½ cup table salt to 2.5 litres water), for 8 minutes per 500g up to 1kg, or 5 minutes per 500g for larger specimens (timed from when the water returns to the boil). Refresh them in iced water then twist off legs and claws, crack and remove the meat with a crab pick, skewer or crochet hook. Tip the body of the crab over and, from underneath, lift off the top shell, most of the inedible organs will come away attached to the shell. Break off the eyes and the shell holding them in place. Lift out and discard the grey feathery gills (deadman’s fingers) from the body, use a small spoon to remove the internal organs, then wipe clean with a damp cloth. Some people like to keep the yellow “mustard” (liver) to add a deeper flavour to the dish. Quarter the crab and pick out all the meat from the body.
If stir-frying or marinating crabs, it is easiest to work with uncooked (green) Blue Swimmers as they are already dead, clean as above without removing legs and claws, quarter the body and crack legs and claws with nut crackers so flavours can penetrate.
Serve boiled crab with Asian dipping sauces or mayonnaise (flavoured with mustard, garlic, or herbs), or hot melted butter with a squeeze of lemon juice. Do not re-cook cooked crabs, pick the meat and use it in salads, as a garnish for soups, tossed through hot pasta or in dishes where it’s only lightly reheated such as crab cakes and omelettes.
Other Crab Information
All crabs shed their shells from time to time as they grow. Once they’ve moulted they have a period of about 2 hours when their new shell is developing and hardening and they are edible shell-and-all. So “soft shell crabs” are not a particular species of crab, but any crab that’s undergoing this process. Some crabs, however, are more commonly sold with soft shells. On the east coast of the USA it’s the highly prized Blue Crab that is harvested from the wild. In Australia high-tech aquaculture has begun, with Blue Swimmer and Mud Crabs being carefully monitored by robotics that detect when the crabs have just moulted. The crabs are then removed from the water which stops the recalcification of their shells (as they can no longer access calcium from the water).
Crab sticks aren’t made from crab. Their official name is surimi and they’re made from inexpensive fish with flavourings and colourings added.
Many British and North American recipes talk about brown and white meat in Crabs. The brown meat is the internal organs (sometimes also called oily, or fatty, meat), prized in some cultures, but generally not used in Australia (except for the “mustard” mentioned above).
Dressed Crabs, often sold in the UK, refers to cooked crab-meat presented in the cleaned top shell in rows, usually with a row of brown meat on both sides and a row of white meat in the middle. It may be pure, but may also have breadcrumbs or seasonings added.