Seafood & Fish
Seafood comprises all bony fishes and the more primitive sharks, skates, rays, sawfish, sturgeons, and lampreys; crustaceans such as lobsters, crabs, shrimps, prawns, and crayfish; mollusks, including clams, oysters, cockles, mussels, periwinkles, whelks, snails, abalones, scallops, and limpets; the cephalopod mollusks—squids, octopuses, and cuttlefish; edible jellyfish; sea turtles; frogs; and two echinoderms—sea urchins and sea cucumbers.
Seafood & Fish are comprise of varied species and varieties, therefore I have used the generic or most common family name in the list.
A broad term for fish that have, or have had, a shell of some kind. The shell is a type of external skeleton that gives protection and structural support to the fish. Shellfish are divided into two basic categories based on the degree of shell hardness. Crustaceans have a shell-like exoskeleton—usually jointed. This group includes lobsters, spiny lobsters, crabs, shrimp, crayfish and barnacles. The second group, mollusks, has one or two harder shells or have moved beyond the need for a shell. They include the unipods (one shell—also called gastropods), such as the abalone, conch, snail and periwinkle; the bivalves (two shells), such as the clam, scallop, mussel and oyster; and the cephalopods (without shells), such as the octopus and the squid.
Mollusks are one of the two main classifications of shellfish (the other is crustacean). Mollusks cover their soft bodies with a shell of one or more parts, or have developed beyond the need for a shell. There are three classes of mollusks: gastropods, also called univalves, with a single, usually spiral shell (e.g. snail, conch); bivalves, with two shells held together by a muscle (e.g. mussel, oyster); and cephalopods, who have shed their need for external shells (e.g., octopus, squid) but have an internal shell, which is called a pen.
The term “fish” most precisely describes any non-tetrapod craniate (i.e. an animal with a skull and in most cases a backbone) that has gills throughout life and whose limbs, if any, are in the shape of fins. A typical fish is ectothermic, has a streamlined body for rapid swimming, extracts oxygen from water using gills or uses an accessory breathing organ to breathe atmospheric oxygen, has two sets of paired fins, usually one or two (rarely three) dorsal fins, an anal fin, and a tail fin, has jaws, has skin that is usually covered with scales, and lays eggs.