''Macrourus'' is a small
benthopelagic
The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of ...
genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
rattail
Grenadiers or rattails are generally large, brown to black gadiform marine fish of the subfamily Macrourinae, the largest subfamily of the family Macrouridae. Found at great depths from the Arctic to Antarctic, members of this subfamily are amo ...
s from the
family
Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
Macrouridae
Macrouridae is a family of deep sea fish, a diverse and ecologically important group, which are part of the order of cod-like fish, the Gadiformes. The species in the Macrouridae are characterised by their large heads which normally have a sing ...
.
General features
The species in the genus ''Macrourus'' have large broad heads which are over four times as deep as they are long with a snout which varies from rounded to bluntly pointed, with a substantial modified spiny scale at its tip. They have a strong, suborbital ridge that extends onto
preopercle
The operculum is a series of bones found in bony fish and chimaeras that serves as a facial support structure and a protective covering for the gills; it is also used for respiration and feeding.
Anatomy
The opercular series contains four bon ...
and ends with a sharp point. The eyes have a diameter of around one third of the length of the head. They have small teeth which are set in in moderate to broad bands in the
premaxilla
The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammals h ...
which taper posteriorly and ending well short of the ends of the lips; the mandibular band is either 3 or 4 teeth wide at the
symphysis
A symphysis (, : symphyses) is a fibrocartilaginous fusion between two bones. It is a type of cartilaginous joint, specifically a secondary cartilaginous joint.
# A symphysis is an amphiarthrosis, a slightly movable joint.
# A growing together o ...
, narrowing to 1 row posteriorly and extending to about the end of the lips. They have a serrated spiny
dorsal fin
A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...
ray; the
pelvic fin
Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...
usually has 8 or 9 rays. The anus is at the
anal fin
Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...
, there is no
photophore
A photophore is a specialized anatomical structure found in a variety of organisms that emits light through the process of boluminescence. This light may be produced endogenously by the organism itself (symbiotic) or generated through a mut ...
. Their maximum size is probably around .
Habitat, distribution and biology
The species of ''Macrourus'' are found on the upper- to middle
continental slope
A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges.
The continental margi ...
which are restricted to cold temperate and polar waters in both the North and South Atlantic as well as in the
Southern Ocean
The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the world ocean, generally taken to be south of 60th parallel south, 60° S latitude and encircling Antarctica. With a size of , it is the seco ...
. They are found at depths from around to greater than . They normally prefer temperatures of between , although one species, the Antarctic roughhead (''
Macrourus whitsoni''), has been collected at temperatures which were slightly below .
[
]
Fisheries
''Macrourus'' species are important food fishes in the North Atlantic and off the Patagonian coast of Argentina.[ They are normally considered as ]bycatch
Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...
in the north eastern Atlantic but they are landed and the weight of catches landed between 1990 and 2015 varied from almost none to 4,000 tonnes.
Taxonomy and species
There is a controversy about the identification of the type species
In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
of this genus; ''Macrourus rupestris'' was named as the type species by Bloch
Bloch is a surname of German origin. Notable people with this surname include:
A
*Adele Bloch-Bauer (1881–1925), Austrian entrepreneur
*Albert Bloch (1882–1961), American painter
*Alexandre Bloch (1857–1919), French painter
*Alfred Bloch ( ...
but this name is a synonym
A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...
of ''Coryphaenoides rupestris
''Coryphaenoides rupestris'' is a species of marine ray-finned fish in the family Macrouridae. Its common names include the rock grenadier, the roundnose grenadier and the roundhead rat-tail. In France it is known as ''grenadier de roche'' and in ...
''. In 1917 Jordan
Jordan, officially the Hashemite Kingdom of Jordan, is a country in the Southern Levant region of West Asia. Jordan is bordered by Syria to the north, Iraq to the east, Saudi Arabia to the south, and Israel and the occupied Palestinian ter ...
proposed that ''Macrourus berglax'' be designated the type species, but this also lacks clarity as Sundevall
Carl Jakob Sundevall (22 October 1801 in Högestad – 2 February 1875) was a Swedish zoologist.
Sundevall studied at Lund University, where he received a Ph.D. in 1823. After traveling to East Asia, he studied medicine, graduating as a Doctor ...
was of the view that the fish named as ''berglax'' by Gunnerus was in fact ''C. rupestris'' and that ''M. berglax'' should be named ''M. fabricii''. This is still to be resolved by the ICZN
The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its formal author, t ...
.
References
{{Authority control
Macrouridae
Marine fish genera
Ray-finned fish genera
Taxa named by Marcus Elieser Bloch