Shellfish as survival food
Main types of edible shellfish
A shellfish is an aquatic animal having a shell including crabs, lobsters and other crustaceans. There are over 50,000 different types of mollusc known to exist and these are an important source of protein in a survival situation. Molluscs include seawater and freshwater shellfish, snails, (terrestrial and aquatic), squid, cuttlefish, octopus and sea urchins. Snails and bivalve shellfish are found in all waters worldwide. All molluscs (with the exception of oysters and sea urchins) must be cooked by steaming, boiling or roasting in their shells; individual cooking instruction are added below. Not to everyone's taste, even when starving, but molluscs can be added to stews of vegetables to make a tastier and more nourishing meal (than you might otherwise have had). Shellfish accumulate pollutants and biological pathogens, in particular shellfish that live in sediment (clams) or filter feeders (mussels) as these can host E. Coli. Always harvest shellfish in areas where the water is clear and the beaches are clean. Never harvest shellfish in waters that have lots of shipping traffic or where industrial pollutants or human waste is fed into the sea.
Bivalves (pelecypoda) are soft–bodied animals that are protected by two hard shells, hinged together. Common edible bivalves are clam, mussel, cockle, oyster and scallop.
How to prepare and cook bivalves
Rest the hinge of the shell on a flat surface, insert a small knife into one of the openings on either side of the shell, just above the hinge and prise open slightly. Insert the blade in the opposite side and prise open. Sever the muscle attaching the meat to the shell to remove the flesh discarding the dark coloured meat. Rinse well under cold running water. If the scallops are large, slice the white flesh in half horizontally.
Scallops only require a very short cooking time or they become tasteless and rubbery. Poach for a couple of minutes in water or grill for 5-10 minutes or until cooked through. Scallops can be fried in pre–heated oil or butter in a frying pan for 2-3 minutes.
Wash the clams well before cooking, the best way is to scrub them under cold running water with a stiff brush. Throw away (or use as bait) any that have broken, cracked or open shells or any that do not close when tapped firmly.
Steam clams over boiling water until the shells have just opened (takes 5–10 minutes). Discard any clams that do not open during the cooking as they were dead before you started.
Wash and scrub the shells thoroughly under cold running water. Discard any damaged shells and any open ones that do not close when tapped firmly.
Cook cockles in a large pan with a little water (adding any flavourings available to enrich the cooking liquid), heat gently, shaking the pan occasionally for about 5 minutes or until the shells have opened. Drain well and eat them straight away. Discard any unopened cockles.
Use oysters that are tightly shut or which close when tapped. Any oysters that stay open are dead and must be discarded. To separate the shells, place the oyster on a level surface with the flat shell uppermost and the hinged edge facing you. Hold by firmly pressing down with the palm of your hand. Insert the tip of a knife blade into the small gap in the hinge and ease the shells apart by levering upwards with a twisting movement. Slide the blade along the inside edge of the upper shell to sever the muscle that holds the shells together. Discard the top shell and retain as much of the liquor in the lower shell as possible. Remove any broken shell with the point of the knife. To cut the oyster loose, grip the lower shell firmly and run the knife blade under the oyster meat to sever the muscle attaching it to the shell.
Oysters are usually eaten raw but can be grilled lightly.
Blue Mussel (Mytilus edulis):
These are found worldwide in most Polar and temperate waters. In North America, mussels are circumpolar in distribution extending south in the western Atlantic Ocean to South Carolina. They may be found in habitats ranging from slightly brackish shallow estuaries to highly saline deep offshore environments, but tend to occur in bays and estuaries that have elevated levels of nutrients from land run–offs, causing an increase in phytoplankton. In other regions of the world, mussels are found in the rocky shores along the coastlines, bays and river mouths, where the mussels attach themselves to submerged surfaces.
Scrub the mussels well under cold running water using a stiff brush and remove any barnacles or weed. Cut off the beards with scissors or sharp knife. Discard any shells that are broken, cracked or open or any shells that do not close when tapped firmly.
Live mussels are usually steamed directly in stock or wine; in a survival situation water may have to suffice – use anything available to flavour the water. Bring the water to the boil and add the closed mussels. Steam for 5 minutes and discard any that have not opened.
The Asian green mussel (Perna viridis)
The Asian green mussel is a native of the tropics, from the north–west Indian Ocean and western Pacific Ocean. It is found from the Persian Gulf to the Philippines and from the East China Sea in the north to Indonesia in the south. It is an important aquaculture species, particularly in China, India, Thailand, Singapore, Indonesia and the Philippines. It has also been introduced for culture in many south Pacific islands, such as Fiji and eastern Polynesia. The Asian green mussel has been accidentally introduced to Trinidad in the Caribbean and then spread (probably by currents and shipping) to the coast of nearby Venezuela. In 1999, it was found clogging the intake canals of power plants on the Florida coast. It is expected that the mussels will spread south in water currents along the American coastline to the Florida Keys.
Preparation and cooking:
The same as blue mussels.
In the summer, all tropical mussels should be regarded as poisonous.
Do not eat shellfish that are not covered by water at high tide.
Gastropods (also called univalves) are a type of mollusc that have a single valve (a shell, which is sometimes reduced or even absent) and a muscular foot. There are over 90,000 species of gastropods worldwide, both in the water and on land.
How to prepare and cook Gastropods
Common Limpet (Patella vulgata)
This mollusc is found in cooler waters of the Atlantic Ocean and the Pacific Ocean. Limpets cling tightly to a rock (using the muscular foot). During the day, limpets move around by rippling the muscles of the foot in a wave–like fashion, looking for food. They return to the same place on their rock each night.
Rinse in fresh water.
Fry them (shell side up) for 4–5 minutes when they fall out of their shells. The dark green dome on the top of the limpet is the gut. It is easily separated. Some people like to eat the limpet with the gut sack in place other prefer not to, but it is harmless and can be eaten. Limpets have a distinct taste, fishy and seaweed flavour but they are very chewy. They can be more palatable if fried then added to a stew and slow cooked for a long time.
The nobbled whelk lives subtidally and is migratory, alternating between deep and shallow water, depending on the time of year. During the weather extremes of the summer and winter months, these sea snails live in deep water, at depths of up to 48 m. In the milder weather of the spring and autumn they live in shallow water, on near-shore or intertidal mud flats and sand flats.
If you do cook them from fresh then make sure you wash them thoroughly in several changes of water then leave them to soak for a couple of hours.
They only need minimal cooking of about 10 to 15 minutes in boiling salted water, otherwise the flesh will be rubbery.
The common periwinkle or winkle (Littorina littorea) is a species of small edible sea snail native to the rocky shores of the northeastern, and introduced to the northwestern, Atlantic Ocean. The common periwinkle is mainly found on rocky shores in the higher and middle intertidal zone. It sometimes lives in small tide pools. It may also be found in muddy habitats such as estuaries. The meat is high in protein (15%), omega-3 fatty acids and low in fat (1.4%).
Drop the periwinkles into several changes of clean water and stir around gently until no sand or sediment is present in the cleaning water.
Bring salted water to a rolling boil and drop the periwinkles in to it. Boil for 3–5 minutes (if you cook them longer they will be chewy). To get at the flesh you need to use a matchstick or toothpick.
The Queen Conch or Pink Conch (Strombus gigas, named by Linnaeus in 1758), is found in warm shallow waters in grass beds of the Caribbean Sea. In North America, a conch is often identified as a queen conch, found off the coast of Florida. All parts of the conch meat are edible raw or cooked.
To prepare smaller shells:
Lightly scrub and rinse off the conch shells with cold water.
To cook smaller shells:
Fill a pot with salted water and bring to a boil. Reduce heat to a simmer and add the conch shells to the pot. Simmer them for 3 to 5 minutes and remove from heat, letting them cool briefly in the liquid. Pick out the meat with a small stick.
To prepare larger shells:
Break open the shell and trim around the meat. Slice off all the dark skin to leave the white internal flesh. Slice this white meat up.
To cook larger shells:
Boil or fry the sliced up white meat for 3 to 5 minutes. Conch meat can be tough and if this is the case add to a stew of vegetables and simmer for 20 minutes.
The Cone Shells
All freshwater river and sea snails are edible but the cone shell is venomous. The cone shell is the most highly evolved species of all shellfish. These carnivores use a poison dart to capture their prey. When the prey is located and is sufficiently close, a hollow, barbed poison dart that is attached to the end of the proboscis is impaled into the hapless victim like a harpoon.
The venom contains a cocktail of toxins called conotoxins (similar in its actions to curare), which target the nerve centres bringing about a total or partial paralysis of the prey. The harpoon is tethered by a fine thread (like a fishing line) that enables the predator to reel in the immobilised prey into its now dilated mouth. Although human encounters are rare and documented deaths are low, if you find these molluscs, be aware that they are fatal to humans.
Five more cone shells, which are dangerous to humans but not necessarily fatal:
These molluscs will attack if handled; they are mentioned here because they are widespread, some are fatal with no known anti–venom for their toxin.
Chitons are large snails of 1 – 5 cm (0.4 – 2 inches). They cling to rocks above the surf line. They are widespread around the world and come in many shapes, ranging from flat oblong to almost round and in many colours. Roast them in their shells and eat them by picking out the flesh.
Part two will be published in April 2017.