Shellfish are animals with no fins, vertebrae or skull, living in a shell. Their muscles are soft, which makes the meat tender. Like finfish, they are very nutritious. They are rich in the minerals calcium, phosphorous, iron, copper, magnesium, and iodine. Although the amounts vary with the type of shellfish, vitamins A, B, and D are usually present. Shellfish are also a good source of protein. Unlike finfish, which have varying fat contents, all shellfish are lean and low in salt, making molluscs and crustaceans excellent choices for low calorie and low sodium diets. There are two types of shellfish: Mollusks and Crustaceans. **MOLLUSCS** Latin molluscus = soft. Molluscs are soft bodied animals with a hard external shell (mussels, winkles, snails), or an internal shell (sea hares, cuttlefish) or have lost their shell in the course of evolution (nudibranchs). Molluscs have a mantle that secretes the calcium carbonate that makes up the shell. They inhabit numerous different environments with a large number living in the sea. Octopuses and squids have evolved to intelligent mobile forms with complex behaviour. A shellfish with a soft body which may be completely or partially enclosed in a shell e.g. Clams, mussels, scallops, and oysters. 1. **CLAMS** There are different types of clam: Hard, soft, and surf clams are found in the Atlantic. Butter, littleneck, razor and piso clams are scattered along the floor of the Pacific. Clam meat is orange in colour and can be used in any recipe which calls for oysters. They can be eaten raw, steamed, boiled, baked or fried; the method of preparation depends partly on size and species. Clam chowder is a popular soup in the U.S. and Canada. In Italy, they are often an ingredient of mixed seafood dishes, or are eaten together with pasta. 2. **MUSSELS** Mussels are found in fresh and salt-water, but only the salt-water mussels are eaten. Marine mussels are abundant in the low and mid intertidal zone in temperate seas of the northern and southern hemispheres. Within their geographic range, some species prefer salt marshes or quiet bays, while others thrive in pounding surf, completely covering exposed wave-washed rocks. The mussel's external shell is composed of two halves that protect it from predators and desiccation. Protruding from a valve is an enlarged structure called the umbo, which indicates the dorsal surface of the mussel. Mussels can be smoked, boiled or steamed. As for all shellfish, mussels should be alive just before they are cooked because they quickly become toxic after they die. A simple criterion is that live mussels, when in the air, are tightly shut; open mussels are dead and should be discarded. Also closed mussel shells that are unusually heavy should be discarded as well. They usually contain only mud and can be tested by slightly moving the two shells away from each other. The mussel shells open by themselves when cooked. 3. **SCALLOPS** There are different types of scallops: Sea scallops are the larger variety and are taken from the North and Mid-Atlantic waters. Bay scallops are smaller and taken from bays, ranging from New England to the Gulf of Mexico. Calico scallops from Florida have become more popular in recent years Sea scallops from Alaska are also becoming increasingly popular. Scallops differ from other molluscs as they are active swimmers. It snaps its shell and spurts out a jet of water allowing it to move about. This strange form of locomotion causes the development of an over-sized muscle called the abductor muscle. Scallops may be substituted for shrimp in most recipes. 4. **OYSTERS** Oysters can be eaten half shelled, raw, smoked, boiled, baked, fried, roasted, stewed, canned, pickled, steamed, broiled (grilled) or used in a variety of drinks. Preparation can be as simple as opening the shell, while cooking can be as spare as adding butter and/or salt, or can be very elaborate. One dozen raw oysters contain approximately 110 calories, and are rich in zinc, iron, calcium, and vitamin A. Fresh oysters must be alive just before consumption. There is a simple criterion: oysters must be tightly closed; oysters that are already open are dead and must be discarded. To confirm if an open oyster is dead, tap the shell. A live oyster will close and is safe to eat. Dead oysters can also be closed, but will make a distinct noise when tapped and are called "clackers." Opening oysters requires skill, for live oysters, outside of the water, shut themselves tightly with a powerful muscle sealing their fluids. An alternative is to cook them in the shell – the heat kills the oysters and they open by themselves. Cooked oysters are slightly sweet-tasting and considered savory, and the varieties are mostly equivalent. There are three types of oysters around the coasts of America: Eastern oysters are found or cultivated from Massachusetts to Texas along the East and Gulf coasts. Pacific oysters are found or cultivated along the West coast from Washington to Mexico. Western, or Olympia, oysters are also found or cultivated along the West coast from Washington to Mexico. In England, Whitstable in Kent is well known for it’s oysters, so much so, they have annual oyster festivals. 5. **COCKLES** Cockles(Cardium edule)are common edible European bivalve molluscs, having a rounded shell with radiating ribs. A cockle's shell is more domed and much smaller than the similar shaped clam. Each animal has two of these shells (bivalve: marine or freshwater mollusc having a soft body with platelike gills enclosed within two shells hinged together). Cockles live on open sandy areas of the intertidal zone, feeding in shallow water when submerged and burying themselves just under the ground surface while the tide is out. They are relatively easy to harvest with a rake and bucket around the coasts while the tides are out, which can be a dangerous activity due to quicksands and changing tides. Cockles are edible and usually enjoyed pickled in vinegar. They have a meaty, firm texture similar to lobster and have a sharp, acid taste. **CRUSTACEANS** A shellfish with ‘crust-like’ shells which possess segmented, elongated bodies with eyes mounted on stalks. Their bodies may or may not be symmetrical e.g. Lobsters, crabs, shrimps and prawns. 1. **LOBSTERS** Lobsters vary in general appearance: Northern lobsters have pincers and they are found off the coasts of Maine and Massachusetts. Spiny or rock lobsters do not have pincers. They pick their way along the Florida and California coasts. Like most arthropods, lobsters must molt in order to grow, leaving them vulnerable during this time. During the molting process, several species may experience a change in color.Lobsters live on rocky, sandy, or muddy bottoms from the shoreline to beyond the edge of the continental shelf. They generally live singly in crevices or in burrows under rocks. 2. **CRABS** True crabs have five pairs of legs, the first of which are modified into a pair of claws and are not used for locomotion. About 850 species of crab are freshwater or (semi) terrestrial species; they are found throughout the world's tropical and semi-tropical regions. Crabs make up 20% of all marine crustaceans caught and farmed worldwide, with over 1½ million tonnes being consumed annually. There are three common types of crabs found in America: Blue crabs are found along the Atlantic and Gulf coasts. They are soft shelled crabs. This is not a separate species, they have molted and their new shell has not had time to harden. Dungeness crabs inhabit the Pacific. King crabs lives in colder waters off the Alaskan coast. 3. **SHRIMPS** There are various species of shrimp. Raw shrimp is distinguished by colour. When cooked, however, all shrimp turn pinkish-red in colour. For example: Common or White shrimp is greenish- grey in colour. Brown or Brazilian shrimp is brownish-red in colour. Pink or coral shrimp is coloured pink or coral. Recipes using shrimp form part of the cuisine of many cultures: examples include scampi. As with other seafood, shrimp is high in calcium and protein but low in food energy.. A shrimp-based meal is also a significant source of cholesterol from 7mg to 251 mg per 100g of shrimp, depending on the method of preparation 4. **PRAWNS** Prawns are found in temperate and tropical waters. They resemble and are often mistaken for large shrimp. Unlike shrimp, however, prawns do not possess a visible vein which requires cleaning. In Spain, gambas al ajillo (translated to prawn pilpil) is a popular dish with both the locals and tourists. Traditionally, gambas al ajillo and other tapas are served in cazuelas de barro (translated to earthenware ramekins.