Bivalve molluscs are any shellfish with a double hinged shell, many of which are commonly referred to as clams; ‘clam’ once meant ‘shut’ and these creatures can shut their shells tightly to protect themselves from predators.Many of Australia’s most popular shellfish, such as Oysters, Scallops and Mussels, are bivalves. But there are also have some equally delicious, less commonly used (therefore less expensive) bivalves, mainly Vongole and Pipis. Although Australia doesn’t have the large range of clams available in North America and Europe, we do have some other occasionally-seen clams, such as Surf Clams, Sydney Cockles, Blood Cockles and Razor Clams.
Vongole (Katelysia scalarina, K.peronii and K.rhytiphora) are members of the venus shell family (their name means ‘clams’ in Italian). Found around the southern Australian coast from Fraser Island in Queensland to Cape Leeuwin in WA (including Tasmania) and harvested from sheltered or sandy sub-tidal sediment of tidal flats and estuary mouths, they were previously known as sand cockles. The larger K.scalarina are tidal, while the smaller K.rhytiphora are inter-tidal. Both the SA and Tasmanian fishery are increasing and there have been aquaculture trials in Port Stephens (NSW) with K.rhytiphora. Shells are almost oval with concentric ridges, and range from white to light brown in colour, sometimes with darker zigzag markings; K.scalarina are pale yellow and K.rhytiphora, greyish-purple. Shell diameter ranges from about 2-5cm, with K.scalarina being the largest and K.rhytiphora the smallest.
Pipi (Donax deltoides) belongs to a related family (the Donacidae, or Pipi, family), and is also known as Coorong cockle, eugarie, Goolwa cockle and ugari. It’s found all around the Australian coast but is mainly hand-harvested from the inter-tidal zone of sandy surf beaches south from the NSW-Queensland border to the beginning of the Great Australian Bight in SA. Its smooth, wedge-shaped, cream to pale brown shell can sometimes be slightly yellow or green and have pinky-purple bands and averages 5-6cm in diameter (but can grow to around 8cm); those harvested from SA are typically smaller than those from NSW and Victoria. As the most common sizeable mollusc found along ocean beaches in NSW, they constituted an important food source for indigenous Australians for thousands of years, as is evidenced by the many middens of Pipi shells left behind.
Surf Clam (Dosinia caerulea), also called dosinia, is another member of the venus shell family, the same family as the American Quahogs (or Hardshell Clams), the Warty, and Smooth, Venus Clams and Carpet-shell Clams found in the Mediterranean. Its rough, circular shell, about 3-4.5cm in diameter, varies in colour from cream through greyish white or pale yellow to light brown, and has sculpted, concentric ridges, often with darker patterning.
Main Article : Surf Clam
Other clams occasionally seen in retail shops or harvested recreationally in various parts of Australia include:
Sydney Cockle (Anadara trapezius) is found in estuaries, mud flats and sea-grass beds. Its shell can be up to 8cm in diameter and has prominent, outward-radiating ribs.
Blood Cockle (Anadara granosa) is named for the reddish liquid released when it’s opened and the sometimes reddish tinge of its shell, which is usually about 6cm in diameter. It is found inter-tidally in northern Australia.
Razor Clams, also sometimes referred to as razor fish, have either a long narrow shell, (like an old-fashioned cutthroat razor), or a long wedge-shaped shell (like an elongated fan). Two species, Atrina tasmanica and Pinna bicolor, both with wedge-shaped shells, are harvested in sand or mud near the low water mark on very sheltered bays in SA.
Buying Bivalve Molluscs
Clams, Cockles and Pipis are all sold live. Look for brightly coloured, intact, lustrous shells, that are closed or close when tapped or gently squeezed, and a pleasant fresh sea smell.
Due to their sandy habitat, they can contain a bit of grit; ask your fishmonger if they have been purged (stored in aerated saltwater for at least 24 hours to eliminate sand), if they haven’t, see purging instructions.
Storing Bivalve Molluscs
Live shellfish should be consumed as soon as possible after purchase. Place them in a container, cover with a damp cloth and store in the warmest part of the refrigerator, which is usually the crisper (optimum 5°C), ensuring that the covering remains damp.
Before cooking, discard any shells that are open and don’t close when tapped or gently squeezed (you may need to give them 10-20 minutes out of the fridge to warm up first). Freeze meat for up to 3 months below -18ºC.
Cooking Bivalve Molluscs
- If they haven’t been purged, place them in a solution of cool water and sea salt (30g salt to each litre of water) for several hours, or overnight, in a cool part of the house (if you refrigerate them they’ll close up and won’t ‘spit out’ the sand).
- The shells yield an average of 20-30% meat, so allow around 600g of whole shells per person as a main course.
- Vongole have a medium flavour and moist, firm flesh. Pipis have a slightly stronger, richer flavour, and can occasionally be a bit chewy.
- All clams, cockles and pipis go well with chilli, coriander, garlic, parsley, tomato and white wine, while pipis also work with stronger flavours such as anchovies, Chinese black beans, ginger, soy sauce and Worcestershire sauce. They all lend themselves to a wide range of cooking styles, including steaming, poaching, stir-frying, baking, grilling, barbecuing (in the shell), smoking and pickling; and, when very fresh, they’re great served raw (sashimi). The firm flesh works particularly well in soups, curries and stir-fries.
- Due to their similarities, Vongole, Pipis and other clams can be substituted for one another in many recipes and are often a good substitute for Blue Mussels.
- Remember that they need very little cooking and are ready virtually as soon as the shell opens. When cooking a large batch, it’s best to remove the individual shells from the pan as each one opens, so as not to overcook them. There are often a few stubborn shells that don’t open regardless of how long they’re cooked, traditional wisdom was to discard these (as they may have already been dead prior to cooking), you can however pry them open over the sink, and, if they smell good, they’re good to eat; if they’re bad your nose will tell you!
- Remove the meat from the shells or serve them shell and all. If serving in the shell, remember to put a large bowl on the table for discarded shells with some finger bowls and big napkins.