| Grenadiers | |
|---|---|
 | |
| Coryphaenoides leptolepis | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Gadiformes |
| Family: | Macrouridae |
| Subfamily: | Macrourinae Bonaparte, 1831[1] |
Grenadiers orrattails are generally large, brown to blackgadiform marinefish of thesubfamilyMacrourinae,[1] the largest subfamily of thefamilyMacrouridae. Found at great depths from theArctic toAntarctic, members of this subfamily are amongst the most abundant of the deep-sea fish.[2]
The macrourins form a large and diverse family with 28 extant genera recognized (well over half of the totalspecies are contained in just three genera,Coelorinchus,Coryphaenoides, andNezumia). They range in length from about 10 cm (3.9 in) inHymenogadus gracilis to 2.1 m (6.9 ft) inAlbatrossia pectoralis. Several attempts have been made to establish a commercial fishery for the most common larger species, such as thegiant grenadier, but the fish is considered unpalatable, and attempts thus far have proven unsuccessful.[3] The subfamily as a whole may represent up to 15% of the deep-sea fish population.
Rattails, characterized by large heads with large mouths and eyes, have slender bodies that taper very much to very thin caudal peduncles or tails (except for one species without a caudal fin): this rat-like tail explains the common name "rattail" and the name of the subfamily and the surname are derived from the Greek makros meaning "big" and Oura meaning "tail". The first dorsal flat is small, tall and pointed (and may have rays modified into spines); The second dorsal fin runs along the rest of the back and connects to the tail and the large anal fin. The scales are small.
As with many deep-living fish, thelateral line system in grenadiers is well-developed; it is further aided by numerouschemoreceptors located on the head and lips and chemosensorybarbels underneath the chin.Benthic species haveswim bladders with unique muscles attached to them. The animals are thought to use these muscles to "strum" their bladders and produce sound, possibly playing a role in courtship and mate location. Light-producing organs,photophores, are present in some species; they are located in the middle of the abdomen, just before the anus and underneath the skin.
Grenadiers have been recorded from depths of about 200 to 7,000 m (660–22,970 ft), and are among the most common benthic fish of the deep (however, two genera are known to prefer the midwater). They may be solitary or may form large schools, as with the roundnose grenadiers. The benthic species are attracted to structural oases, such ashydrothermal vents,cold seeps, andshipwrecks. They are thought to be generalists, feeding on smaller fish, pelagiccrustaceans, such asshrimp,amphipods,cumaceans, and less oftencephalopods andlanternfish. As well as being importantapex predators in the benthic habitat, some species are also notable as scavengers.
As few rattaillarvae have been recovered, little is known of their life histories. They are known to produce a large number (over 100,000) of tiny (1–2 millimetres or 0.039–0.079 inches in diameter) eggs made buoyant bylipid droplets. The eggs are presumed to float up to thethermocline (the interface between warmer surface waters and cold, deeper waters) where they develop. The juveniles remain in shallower waters, gradually migrating to greater depths with age.
Spawning may or may not be tied to the seasons, depending on the species. At least one species,Coryphaenoides armatus, is thought to besemelparous; that is, the adults die after spawning. Nonsemelparous species may live to 56 years or more. The macrourins, in general, are thought to have low resilience; commercially exploited species may be overfished and this could soon lead to a collapse of their fisheries.
Currently 28 extant genera in this subfamily are recognized:[4]
