Gadidae
Encyclopedia
Gadidae is a family of marine fish, included in the order Gadiformes
. It includes the cod
, haddock
, whiting
, and pollock
.
Most species of gadid are found in temperate waters of the northern hemisphere, although there are some exceptions. They are generally medium sized fish, and are distinguished by the presence of three dorsal fin
s on the back and two anal fins on the underside. Most species have barbel
s on their chin, which they use while browsing on the sea floor. Gadids are carnivorous, feeding on smaller fish and crustacean
s.
Gadids are highly prolific, producing several million eggs at each spawning. This contributes to their high population numbers, which, in turn, makes commercial fishing relatively easy.
Family Gadidae
Cod and related species are plagued by parasites. For example the cod worm, Lernaeocera branchialis, starts life as a copepod
, a small free-swimming crustacean larva
. The first host used by cod worm is a flatfish
or lumpsucker
, which they capture with grasping hooks at the front of their body. They penetrate the lumpsucker with a thin filament which they use to suck its blood. The nourished cod worms then mate on the lumpsucker.
The female worm, with her now fertilized eggs, then finds a cod, or a cod-like fish such as a haddock
or whiting. There the worm clings to the gill
s while it metamorphoses into a plump, sinusoidal, wormlike body, with a coiled mass of egg strings at the rear. The front part of the worms body penetrates the body of the cod until it enters the rear bulb of the host's heart
. There, firmly rooted in the cod's circulatory system, the front part of the parasite develops like the branches of a tree, reaching into the main artery
. In this way, the worm extracts nutrients from the cod's blood, remaining safely tucked beneath the cod's gill cover until it releases a new generation of offspring into the water.
Gadiformes
Gadiformes is an order of ray-finned fish, also called the Anacanthini, that includes the cod and its allies. Many major food fish are in this order. They are found in marine waters throughout the world, and there are also a small number of freshwater species.Common characteristics include the...
. It includes the cod
Cod
Cod is the common name for genus Gadus, belonging to the family Gadidae, and is also used in the common name for various other fishes. Cod is a popular food with a mild flavor, low fat content and a dense, flaky white flesh. Cod livers are processed to make cod liver oil, an important source of...
, haddock
Haddock
The haddock , also known as the offshore hake, is a marine fish distributed on both sides of the North Atlantic. Haddock is a popular food fish and is widely fished commercially....
, whiting
Merlangius merlangus
Merlangius merlangus, commonly known as whiting is an important food fish in the eastern North Atlantic, northern Mediterranean, western Baltic, and Black Sea...
, and pollock
Pollock
Pollock is the common name used for either of the two species of marine fish in the Pollachius genus. Both P. pollachius and P. virens are commonly referred to as pollock. Other names for P...
.
Most species of gadid are found in temperate waters of the northern hemisphere, although there are some exceptions. They are generally medium sized fish, and are distinguished by the presence of three dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
s on the back and two anal fins on the underside. Most species have barbel
Barbel (anatomy)
A barbel on a fish is a slender, whiskerlike tactile organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, sturgeon, the zebrafish and some species of shark...
s on their chin, which they use while browsing on the sea floor. Gadids are carnivorous, feeding on smaller fish and crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s.
Gadids are highly prolific, producing several million eggs at each spawning. This contributes to their high population numbers, which, in turn, makes commercial fishing relatively easy.
Genera and species
The family gadidae includes 24 species, grouped into 13 genera. Some other forms once included here have since been removed to other families. On the other hand, the tadpole cod family Ranicipitidae has now been absorbed into Gadidae, having formerly contained just one species, the tadpole fish (Raniceps raninus).Family Gadidae
- Genus Arctogadus Dryagin, 1932.
- East Siberian codEast Siberian codThe East Siberian cod, Arctogadus borisovi, also known as the toothed cod, is an Arctic fish closely similar to the Arctic cod Arctogadus glacialis and also related to true cods . It has been differentiated in appearance from the Arctic cod by having pronounced chin barbel. Their sides and back are...
(Arctogadus borisovi) Dryagin, 1932 - Arctic codArctic codThe Arctic cod is an Arctic deepwater fish related to the true cod .-Names:The fish has several common names, including polar cod and Greenland cod...
(Arctogadus glacialis) (PetersWilhelm PetersWilhelm Karl Hartwich Peters was a German naturalist and explorer.He was assistant to Johannes Peter Müller and later curator of the Berlin Zoological Museum. In September 1842 he travelled to Mozambique via Angola. He returned to Berlin with an enormous collection of natural history specimens...
, 1872)
- East Siberian cod
- Genus Boreogadus Günther, 1862.
- Polar codPolar codThe polar cod , also known as the Arctic cod, is a fish of the cod family Gadidae, related to the true cod . Note that there is another fish with the common name Arctic cod, Arctogadus glacialis....
(Boreogadus saida) (Lepechin, 1774)
- Polar cod
- Genus Eleginus Fischer, 1813.
- Saffron codSaffron codThe saffron cod , is a commercially harvested fish closely related to true cods . It is dark grey-green to brown, with spots on its sides and pale towards the belly. It may grow to 60 cm and weigh up to 1.3 kg....
(Eleginus gracilis) (Tilesius, 1810) - NavagaNavagaNavaga is a relatively small species of fish in the cod family Gadidae. It inhabits the European arctic and subarctic waters of the Barents, White and Kara Seas, from the Kola Bay to the Ob river estuary....
(Eleginus nawaga) (KoelreuterJoseph Gottlieb KölreuterJoseph Gottlieb Kölreuter , also spelled Koelreuter or Kohlreuter, was a German botanist.Kölreuter was born the son of a pharmacist in Karlsruhe, Germany, and grew up in Sulz. He studied medicine at the University of Tübingen under physician and botanist Johann Georg Gmelin, receiving his PhD in...
, 1770)
- Saffron cod
- Genus Gadiculus GuichenotAlphone GuichenotAntoine Alphone Guichenot was a French zoologist who taught, researched, and participated in specimen collecting trips on behalf of the National Natural History Museum in Paris, including an extensive biological survey of Algeria. His primary fields of research included fish and reptiles...
, 1850.- Silvery cod (Gadiculus argenteus argentus) GuichenotAlphone GuichenotAntoine Alphone Guichenot was a French zoologist who taught, researched, and participated in specimen collecting trips on behalf of the National Natural History Museum in Paris, including an extensive biological survey of Algeria. His primary fields of research included fish and reptiles...
, 1850 - Gadiculus argenteus thori SchmidtJohannes SchmidtJohannes Schmidt may refer to:*Johannes Schmidt , German*Johannes Schmidt , Danish, nicknamed Eel-Schmidt...
, 1914
- Silvery cod (Gadiculus argenteus argentus) Guichenot
- Genus GadusCodCod is the common name for genus Gadus, belonging to the family Gadidae, and is also used in the common name for various other fishes. Cod is a popular food with a mild flavor, low fat content and a dense, flaky white flesh. Cod livers are processed to make cod liver oil, an important source of...
Linné, 1758.- Pacific codPacific CodThe Pacific cod, Gadus macrocephalus, is an important commercial food species. It is also known as gray cod, gray goo, gray wolf, grayest or grayfish. It has three separate dorsal fins, and the catfish-like whiskers on its lower jaw. In appearance, it is similar to the Atlantic Cod...
(Gadus macrocephalus) Tilesius, 1810 - Atlantic codAtlantic codThe Atlantic cod, Gadus morhua, is a well-known demersal food fish belonging to the family Gadidae. It is also commercially known as cod, codling or haberdine....
(Gadus morhua) Linnaeus, 1758 - Greenland codGreenland codThe Greenland cod, Gadus ogac, known variously as rock cod, ogac and uvac is a commercially harvested food fish.In colour the Greenland cod is generally sombre, ranging from tan to brown to silvery. Its appearance is similar to that of other cod species; generally heavy-bodied, elongate, usually...
(Gadus ogac) RichardsonJohn Richardson (naturalist)Sir John Richardson was a Scottish naval surgeon, naturalist and arctic explorer.Richardson was born at Dumfries. He studied medicine at Edinburgh University, and became a surgeon in the navy in 1807. He traveled with John Franklin in search of the Northwest Passage on the Coppermine Expedition of...
, 1836
- Pacific cod
- Genus Melanogrammus Gill, 1862.
- HaddockHaddockThe haddock , also known as the offshore hake, is a marine fish distributed on both sides of the North Atlantic. Haddock is a popular food fish and is widely fished commercially....
(Melanogrammus aeglefinus) (Linnaeus, 1758)
- Haddock
- Genus Merlangius Garsault, 1764.
- Whiting (Merlangius merlangusMerlangius merlangusMerlangius merlangus, commonly known as whiting is an important food fish in the eastern North Atlantic, northern Mediterranean, western Baltic, and Black Sea...
) (Linnaeus, 1758)
- Whiting (Merlangius merlangus
- Genus Microgadus Gill, 1865.
- Pacific tomcod (Microgadus proximus) (GirardCharles Frédéric GirardCharles Frédéric Girard was a French biologist specializing in ichthyology and herpetology.Born in Mulhouse, France, he studied at the College of Neuchâtel, Switzerland as a student of Louis Agassiz. In 1847, he accompanied Agassiz as his assistant to Harvard...
, 1854) - Atlantic tomcod (Microgadus tomcod) (WalbaumJohann Julius WalbaumJohann Julius Walbaum was a physician, naturalist and taxonomist. He was the first to describe many previously unknown species from remote parts of the globe, such as the Great Barracuda , the Chum salmon from the Kamchatka River in Siberia, and the curimatá-pacú Johann Julius Walbaum (30 June...
, 1792)
- Pacific tomcod (Microgadus proximus) (Girard
- Genus Micromesistius Gill, 1863.
- Southern blue whitingSouthern blue whitingThe southern blue whiting, Micromesistius australis, is a cod of the genus Micromesistius, found in the southern oceans where the temperature is between 3° and 7°C, at depths of between 50 and 900 m...
(Micromesistius australis) Norman, 1937 - Blue whitingBlue whitingThe blue whiting, Micromesistius poutassou, is one of the two species in the genus Micromesistius in the cod family, common in the North-East Atlantic ocean, from Morocco to Iceland and Spitsbergen. Blue whiting also occur in the North-West Atlantic ocean between Canada and Greenland. It has a...
(Micromesistius poutassou) (RissoAntoine RissoGiuseppe Antonio Risso , called Antoine Risso, was a Niçard naturalist.Risso was born in Nice, County of Nice, a part of the Duchy of Savoy, and studied under Giovanni Battista Balbis. He published , and . Risso's dolphin was named after him...
, 1827)
- Southern blue whiting
- Genus Pollachius NilssonSven NilssonSven Nilsson was a Swedish zoologist and archaeologist, who was director of the Naturhistoriska Riksmuseet , professor of Natural history at Lund University , and rector of the university...
, 1832.- Atlantic pollock (Pollachius pollachiusPollachius pollachiusPollachius pollachius is a species of marine fish in the Pollachius genus. Together with Pollachius virens it is generally referred to as Pollock. Other names include the Atlantic pollock, European pollock, lieu jaune, and lythe. It is common in the north-eastern parts of the Northern Atlantic,...
) (Linnaeus, 1758) - Saithe (Pollachius virensPollachius virensPollachius virens is a species of marine fish in the Pollachius genus. Together with Pollachius pollachius it is generally referred to in the U.S. as Pollock. Other names include the Boston blues , coalfish and saithe in the UK.This species can be separated from P...
) (Linnaeus, 1758)
- Atlantic pollock (Pollachius pollachius
- Genus Raniceps OkenLorenz OkenLorenz Oken was a German naturalist.Oken was born Lorenz Okenfuss in Bohlsbach in Baden and studied natural history and medicine at the universities of Freiburg and Würzburg. He went on to the University of Göttingen, where he became a Privatdozent , and shortened his name to Oken...
, 1817.- Tadpole fish (Raniceps raninus) (Linnaeus, 1758)
- Genus Theragra LucasFrederic Augustus LucasFrederic Augustus Lucas, Sc.D. was an American museum director.-Early years:Frederic A. Lucas was born March 25, 1852 at Plymouth, Massachusetts.-Career:...
in JordanDavid Starr JordanDavid Starr Jordan, Ph.D., LL.D. was a leading eugenicist, ichthyologist, educator and peace activist. He was president of Indiana University and Stanford University.-Early life and education:...
& EvermannBarton Warren EvermannBarton Warren Evermann was an American ichthyologist. He was born in Monroe County, Iowa, and graduated from Indiana University in 1886. For 10 years, he served as teacher and superintendent of schools in Indiana and California. He was professor of biology at the Indiana State University in...
, 1898.- Alaska pollockAlaska pollockAlaska pollock or walleye pollock is a North Pacific species of the cod family Gadidae. While related to the common Atlantic pollock species of the same family, the Alaska pollock is not a member of the same Pollachius genus.The Norwegian pollock , a rare fish of Norwegian waters, may actually be...
(Theragra chalcogramma) (PallasPeter Simon PallasPeter Simon Pallas was a German zoologist and botanist who worked in Russia.- Life and work :Pallas was born in Berlin, the son of Professor of Surgery Simon Pallas. He studied with private tutors and took an interest in natural history, later attending the University of Halle and the University...
, 1814) - Norwegian pollock (Theragra finnmarchica) Koefoed, 1956
- Alaska pollock
- Genus Trisopterus Rafinesque, 1814.
- Norway pout (Trisopterus esmarkiiTrisopterus esmarkiiTrisopterus esmarkii, the Norway Pout, is a species of fish found in the Barents Sea, North Sea, Baltic Sea, off the coasts of Norway, Iceland, the British Isles and elsewhere in the northeast Atlantic Ocean. It is in the same family as cod. It can generally be found at depths of 100 m to 200 m...
) (NilssonSven NilssonSven Nilsson was a Swedish zoologist and archaeologist, who was director of the Naturhistoriska Riksmuseet , professor of Natural history at Lund University , and rector of the university...
, 1855) - PoutingTrisopterus luscusTrisopterus luscus is a fish belonging to the cod family . It is found along the European coast. Usually grows to 30 cm or less....
(Trisopterus luscusTrisopterus luscusTrisopterus luscus is a fish belonging to the cod family . It is found along the European coast. Usually grows to 30 cm or less....
) (Linnaeus, 1758) - Poor codPoor codThe poor cod, Trisopterus minutus, is a temperate marine fish belonging to the cod family . It is red brown in color and has a pronounced chin barbel. It may grow up to a length of 40cm. It is usually found in small shoals at depths between 10 and 300 meters on muddy or sandy bottoms...
(Trisopterus minutus) (Linnaeus, 1758)
- Norway pout (Trisopterus esmarkii
Parasites
Copepod
Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...
, a small free-swimming crustacean larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
. The first host used by cod worm is a flatfish
Flatfish
The flatfish are an order of ray-finned fish, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the head, one or the other migrating through and around the head during development...
or lumpsucker
Lumpsucker
Lumpsuckers or lumpfish are mostly small scorpaeniform marine fish of the family Cyclopteridae. They are found in the cold waters of the Arctic, North Atlantic, and North Pacific oceans...
, which they capture with grasping hooks at the front of their body. They penetrate the lumpsucker with a thin filament which they use to suck its blood. The nourished cod worms then mate on the lumpsucker.
The female worm, with her now fertilized eggs, then finds a cod, or a cod-like fish such as a haddock
Haddock
The haddock , also known as the offshore hake, is a marine fish distributed on both sides of the North Atlantic. Haddock is a popular food fish and is widely fished commercially....
or whiting. There the worm clings to the gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...
s while it metamorphoses into a plump, sinusoidal, wormlike body, with a coiled mass of egg strings at the rear. The front part of the worms body penetrates the body of the cod until it enters the rear bulb of the host's heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
. There, firmly rooted in the cod's circulatory system, the front part of the parasite develops like the branches of a tree, reaching into the main artery
Artery
Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....
. In this way, the worm extracts nutrients from the cod's blood, remaining safely tucked beneath the cod's gill cover until it releases a new generation of offspring into the water.