Seafood facts for kids
Types of seafood
The following table is based on the ISSCAAP classification (International Standard Statistical Classification of Aquatic Animals and Plants) used by the FAO for the purposes of collecting and compiling fishery statistics. The production figures have been extracted from the FAO FishStat database, and include both capture from wild fisheries and aquaculture production.
|fish||Fish are aquatic vertebrates which lack limbs with digits, use gills to breathe, and have heads protected by hard bone or cartilage skulls. See: Fish (food).
Total for fish:
|Pelagic fish live and feed near the surface or in the water column of the sea, but not on the bottom of the sea. The main seafood groups can be divided into larger predator fish (sharks, tuna, billfish, mahi-mahi, mackerel, salmon) and smaller forage fish (herring, sardines, sprats, anchovies, menhaden). The smaller forage fish feed on plankton, and can accumulate toxins to a degree. The larger predator fish feed on the forage fish, and accumulate toxins to a much higher degree than the forage fish.||
|Demersal fish live and feed on or near the bottom of the sea. Some seafood groups are cod, flatfish, grouper and stingrays. Demersal fish feed mainly on crustaceans they find on the sea floor, and are more sedentary than the pelagic fish. Pelagic fish usually have the red flesh characteristic of the powerful swimming muscles they need, while demersal fish usually have white flesh.||
|diadromous||Diadromous fish are fishes which migrate between the sea and fresh water. Some seafood groups are salmon, shad, eels and lampreys. See: Salmon run.||
|freshwater||Freshwater fish live in rivers, lakes, reservoirs, and ponds. Some seafood groups are carp, tilapia, catfish, bass, and trout. Generally, freshwater fish lend themselves to fish farming more readily than the ocean fish, and the larger part of the tonnage reported here refers to farmed fish.||
|molluscs||Molluscs (from the Latin molluscus, meaning soft ) are invertebrates with soft bodies that are not segmented like crustaceans. Bivalves and gastropods are protected by a calcareous shell which grows as the mollusc grows. Cephalopods are not protected by a shell.
Total for molluscs:
|bivalves||Bivalves, sometimes referred to as clams, have a protective shell in two hinged parts. A valve is the name used for the protective shell of a bivalve, so bivalve literally means two shells. Important seafood bivalves include oysters, scallops, mussels and cockles. Most of these are filter feeders which bury themselves in sediment on the seabed where they are safe from predation. Others lie on the sea floor or attach themselves to rocks or other hard surfaces. Some, such as scallops, can swim. Bivalves have long been a part of the diet of coastal communities. Oysters were cultured in ponds by the Romans and mariculture has more recently become an important source of bivalves for food.||12,585|
|gastropods||Aquatic gastropods, also known as sea snails, are univalves which means they have a protective shell that is in a single piece. Gastropod literally means stomach-foot, because they appear to crawl on their stomachs. Common seafood groups are abalone, conch, limpets, whelks and periwinkles.||526|
|cephalopods||Cephalopods are not protected with a shell. Cephalopod literally means head-foots, because they have limbs which appear to issue from their head. They have excellent vision and high intelligence. Cephalopods propel themselves with a water jet and lay down "smoke screens" with ink. Examples are octopus, squid and cuttlefish. They are eaten in many cultures. Depending on the species, the arms and sometimes other body parts are prepared in various ways. Octopus must be boiled properly to rid it of slime, smell, and residual ink. Squid are popular in Japan. In Mediterranean countries and in Britain squid are often referred to as calamari. Cuttlefish is less eaten than squid, though it is popular in Italy and dried, shredded cuttlefish is a snack food in East Asia. See: Squid (food) Octopus (food).||3,653|
|other||Molluscs not included above||4,033|
|crustaceans||Crustaceans (from Latin crusta, meaning crust ) are invertebrates with segmented bodies protected by hard crusts (shells or exoskeletons), usually made of chitin and structured somewhat like a knight's armour. The shells do not grow, and must periodically be shed or moulted. Usually two legs or limbs issue from each segment. Most commercial crustaceans are decapods, that is they have ten legs, and have compound eyes set on stalks. Their shell turns pink or red when cooked.
Total for crustaceans:
|shrimps||Shrimp and prawns, are small, slender, stalk-eyed ten-legged crustaceans with long spiny rostrums. They are widespread, and can be found near the seafloor of most coasts and estuaries, as well as in rivers and lakes. They play important roles in the food chain. There are numerous species, and usually there is a species adapted to any particular habitat. Any small crustacean which resembles a shrimp tends to be called one. See: shrimp (food), shrimp fishery, shrimp farming, freshwater prawn farming.||6,917|
|crabs||Crabs are stalk-eyed ten-legged crustaceans, usually walk sideways, and have grasping claws as their front pair of limbs. They have small abdomens, short antennae, and a short carapace that is wide and flat. See: crab fisheries.||1,679|
|lobsters||Clawed lobsters and spiny lobsters are stalk-eyed ten-legged crustaceans with long abdomens. The clawed lobster has large asymmetrical claws for its front pair of limbs, one for crushing and one for cutting (pictured). The spiny lobster lacks the large claws, but has a long, spiny antennae and a spiny carapace. Lobsters are larger than most shrimp or crabs. See: lobster fishing.||281|
|krill||Krill are like baby shrimps, except they have external gills and more than ten legs (swimming plus feeding and grooming legs). They are found in oceans around the world where they filter feed in huge pelagic swarms. Like shrimp, they are an important part of the marine food chain, converting phytoplankton into a form larger animals can consume. Each year, larger animals eat half the estimated biomass of krill (about 600 million tonnes). Humans consume krill in Japan and Russia, but most of the krill harvest is used to make fish feed and for extracting oil. Krill oil contains omega-3 fatty acids, similarly to fish oil. See: Krill fishery.||215|
|other||Crustaceans not included above||1,359|
|other aquatic animals||
Total for other aquatic animals:
|aquatic mammals||Marine mammals form a diverse group of 128 species that rely on the ocean for their existence. Whale meat is still harvested from legal, non-commercial hunts. About one thousand long-finned pilot whales are still killed annually. Japan has resumed hunting for whales, which they call "research whaling". In modern Japan, two cuts of whale meat are usually distinguished: the belly meat and the more valued tail or fluke meat. Fluke meat can sell for $200 per kilogram, three times the price of belly meat. Fin whales are particularly desired because they are thought to yield the best quality fluke meat. In Taiji in Japan and parts of Scandinavia such as the Faroe Islands, dolphins are traditionally considered food, and are killed in harpoon or drive hunts. Ringed seals are still an important food source for the people of Nunavut and are also hunted and eaten in Alaska. The meat of sea mammals can be high in mercury, and may pose health dangers to humans when consumed. The FAO record only the reported numbers of aquatic mammals harvested, and not the tonnage. In 2010, they reported 2500 whales, 12,000 dolphins and 182,000 seals. See: marine mammals as food, whale meat, seal hunting.||?|
|aquatic reptiles||Sea turtles have long been valued as food in many parts of the world. Fifth century BC Chinese texts describe sea turtles as exotic delicacies. Sea turtles are caught worldwide, although in many countries it is illegal to hunt most species. Many coastal communities around the world depend on sea turtles as a source of protein, often gathering sea turtle eggs, and keeping captured sea turtles alive on their backs until needed for consumption. Most species of sea turtle are now endangered, and some are critically endangered. The FAO reports 1,418,975 crocodiles were harvested in 2010, but they do not record the tonnage.||296+|
|echinoderms||Echinoderms are headless invertebrates, found on the seafloor in all oceans and at all depths. They are not found in fresh water. They usually have a five-pointed radial symmetry, and move, breathe and perceive with their retractable tube feet. They are covered with a calcareous and spiky test or skin. The name echinoderm comes from the Greek ekhinos meaning hedgehog, and dermatos meaning skin. Echinoderms used for seafood include sea cucumbers, sea urchins, and occasionally starfish. Wild sea cucumbers are caught by divers and in China they are farmed commercially in artificial ponds. The gonads of both male and female sea urchins, usually called sea urchin roe or corals, are delicacies in many parts of the world. See: sea cucumber (food).||373|
|jellyfish||Jellyfish are soft and gelatinous, with a body shaped like an umbrella or bell which pulsates for locomotion. They have long, trailing tentacles with stings for capturing prey. They are found free-swimming in the water column in all oceans, and are occasionally found in freshwater. Jellyfish must be dried within hours to prevent spoiling. In Japan they are regarded as a delicacy. Traditional processing methods are carried out by a jellyfish master. This involve a 20 to 40 day multi-phase procedure which starts with removing the gonads and mucous membranes. The umbrella and oral arms are then treated with a mixture of table salt and alum, and compressed. Processing reduces liquefaction, odor, the growth of spoilage organisms, and makes the jellyfish drier and more acidic, producing a crisp and crunchy texture. Only scyphozoan jellyfish belonging to the order Rhizostomeae are harvested for food; about 12 of the approximately 85 species. Most of the harvest takes place in southeast Asia.||
|other||Aquatic animals not included above, such as ducks, sea squirts (pictured), spoon worms, lancelets and frogs.||336|
|aquatic plants and microphytes||
Total for aquatic plants and microphytes:
|seaweed||Seaweed is a loose colloquial term which lacks a formal definition. Broadly, the term is applied to the larger, macroscopic forms of algae, as opposed to microalga. Examples of seaweed groups are the multicellular red, brown and green algae. Edible seaweeds usually contain high amounts of fibre and, in contrast to terrestrial plants, contain a complete protein. Seaweeds are used extensively as food in coastal cuisines around the world. Seaweed has been a part of diets in China, Japan, and Korea since prehistoric times. Seaweed is also consumed in many traditional European societies, in Iceland and western Norway, the Atlantic coast of France, northern and western Ireland, Wales and some coastal parts of South West England, as well as Nova Scotia and Newfoundland. See: edible seaweed, seaweed farming, aquaculture of giant kelp, laverbread.|
|microphytes||Microphytes are microscopic organisms, and can be algal, bacterial or fungal. Microalgae are another type of aquatic plant, and includes species that can be consumed by humans and animals. Some species of aquatic bacteria can also be used as seafood, such as spirulina (pictured), a type of cyanobacteria. See: culture of microalgae in hatcheries.|
|Total production (thousand tonnes)||168,447|
- See also: Fish processing
Live food fish are often transported in tanks at high expense for an international market that prefers its seafood killed immediately before it is cooked. This process originally was started by Lindeye. Delivery of live fish without water is also being explored. While some seafood restaurants keep live fish in aquaria for display purposes or for cultural beliefs, the majority of live fish are kept for dining customers. The live food fish trade in Hong Kong, for example, is estimated to have driven imports of live food fish to more than 15,000 tonnes in 2000. Worldwide sales that year were estimated at US$400 million, according to the World Resources Institute.
If the cool chain has not been adhered to correctly, food products generally decay and become harmful before the validity date printed on the package. As the potential harm for a consumer when eating rotten fish is much larger than for example with dairy products, the U.S. Food and Drug Administration (FDA) has introduced regulation in the USA requiring the use of a time temperature indicator on certain fresh chilled seafood products.
Fresh fish is a highly perishable food product, so it must be eaten promptly or discarded; it can be kept for only a short time. In many countries, fresh fish are filleted and displayed for sale on a bed of crushed ice or refrigerated. Fresh fish is most commonly found near bodies of water, but the advent of refrigerated train and truck transportation has made fresh fish more widely available inland.
Long term preservation of fish is accomplished in a variety of ways. The oldest and still most widely used techniques are drying and salting. Desiccation (complete drying) is commonly used to preserve fish such as cod. Partial drying and salting is popular for the preservation of fish like herring and mackerel. Fish such as salmon, tuna, and herring are cooked and canned. Most fish are filleted prior to canning, but some small fish (e.g. sardines) are only decapitated and gutted prior to canning.
Seafood is consumed all over the world; it provides the world's prime source of high-quality protein: 14–16% of the animal protein consumed worldwide; over one billion people rely on seafood as their primary source of animal protein. Fish is among the most common food allergens.
The UK Food Standards Agency recommends that at least two portions of seafood should be consumed each week, one of which should be oil-rich. There are over 100 different types of seafood available around the coast of the UK.
Oil-rich fish such as mackerel or herring are rich in long chain Omega-3 oils. These oils are found in every cell of the human body, and are required for human biological functions such as brain functionality.
Whitefish such as haddock and cod are very low in fat and calories which, combined with oily fish rich in Omega-3 such as mackerel, sardines, fresh tuna, salmon and trout, can help to protect against coronary heart disease, as well as helping to develop strong bones and teeth.
Texture and taste
Over 33,000 species of fish and many more marine invertebrate species have been described. Bromophenols, which are produced by marine algae, gives marine animals an odor and taste that is absent from freshwater fish and invertebrates. Also, a chemical substance called dimethylsulfoniopropionate (DMSP) that is found in red and green algae is transferred to animals in the marine food chain. When broken down, dimethyl sulfide (DMS) is produced, and is often released during food preparation when fresh fish and shellfish are heated. In small quantities it creates a specific smell one associates with the ocean, but which in larger quantities gives the impression of rotten seaweed and old fish. Another molecule known as TMAO occurs in fishes and give them a distinct smell. It also exists in freshwater species, but becomes more numerous in the cells of an animal the deeper it lives, so that fish from the deeper parts of the ocean has a stronger taste than species who lives in shallow water. Eggs from seaweed contains sex pheromones called dictyopterenes. These pheromones are also found in edible seaweeds, which contributes to their aroma. However, only a small number of species are commonly eaten by humans.
|Common species used as seafood|
|Mild flavour||Moderate flavour||Full flavour|
|basa, flounder, hake, scup, smelt, rainbow trout, hardshell clam, blue crab, peekytoe crab, spanner crab, cuttlefish, eastern oyster, Pacific oyster||anchovy, herring, lingcod, moi, orange roughy, Atlantic Ocean perch, Lake Victoria perch, yellow perch, European oyster, sea urchin||Atlantic mackerel|
|black sea bass, European sea bass, hybrid striped bass, bream, cod, drum, haddock, hoki, Alaska pollock, rockfish, pink salmon, snapper, tilapia, turbot, walleye, lake whitefish, wolffish, hardshell clam, surf clam, cockle, Jonah crab, snow crab, crayfish, bay scallop, Chinese white shrimp||sablefish, Atlantic salmon, coho salmon, skate, dungeness crab, king crab, blue mussel, greenshell mussel, pink shrimp||escolar, chinook salmon, chum salmon, American shad|
|Arctic char, carp, catfish, dory, grouper, halibut, monkfish, pompano, Dover sole, sturgeon, tilefish, wahoo, yellowtail, Abalone, conch, stone crab, American lobster, spiny lobster, octopus, black tiger shrimp, freshwater shrimp, gulf shrimp, Pacific white shrimp, squid||barramundi, cusk, dogfish, kingklip, mahimahi, opah, mako shark, swordfish, albacore tuna, yellowfin tuna, geoduck clam, squat lobster, sea scallop, rock shrimp||barracuda, Chilean sea bass, cobia, croaker, eel, blue marlin, mullet, sockeye salmon, bluefin tuna|
Fish can form part of a nutritious diet and is a good source of vitamins and minerals; oily fish is rich in omega-3 fatty acid, which may benefit heart health.
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Seafood Facts for Kids. Kiddle Encyclopedia.