Slickheads Temporal range: | |
---|---|
California slickhead, Alepocephalus tenebrosus | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Superorder: | Alepocephali |
Order: | Alepocephaliformes |
Family: | Alepocephalidae Bonaparte, 1846 |
Genera | |
Synonyms | |
|
Slickheads, also known as nakedheads or smoothheads, are deep water fishes that belong to the family Alepocephalidae. They are most commonly found in the bathypelagic layer, which is approximately 3000m below the surface. [1] They get their name from the lack of scales on their heads. Similarly, the scientific name is from the Greek ᾰ̓- (a-, "not"); λέπος (lepos, "scale"); and κεφαλή (kephalē, "head"). It has about 22 genera with ca. 96 species. [2]
The only known fossil genus is Carpathichthys from the Early Oligocene of Poland, although an undescribed species of Bathyprion and several indeterminate taxa are also known from the same formation. Fossil otoliths are also known, dating to the Early Eocene. [3] [4]
The following characteristics are generally shared by the Alepocephalidae family:
Their mouths consist of 80 to 100 razor-sharp teeth, being rather small and feeble. They are shaped in an eel-like elongation, with large eyes, gill rakers that range from moderate to long and numerous, and spineless fins. The single dorsal fin is located posterior to the midpoint of the body and there is no adipose dorsal fin present, there is a pectoral fin ranging from small to rudimentary located below the mid-flank, 4-18 rays, if pelvic fins are present, they exist in the abdominal region, with the origin being before the origin of the dorsal fin, they have forked caudal fins, and a tube above the base of pectoral fin that connects to a luminous gland on the shoulder girdle. They have no swim bladder. [2] Some species bear photophores. [5]
Their early life development is from large eggs directly into yolk sac juveniles that travel in deep waters. [6]
The largest species is the Yokozuna slickhead, Narcetes shonanmaruae. [7]
It’s been thought that as the Alepocephalidae age, they move down layers in the ocean, (mesopelagic waters and bathypelagic waters) due to mostly adolescent Alepocephalidae being reported near the surface, although there have been sightings of juveniles only several meters above the sea floor, which could suggest that some species may travel between different depths throughout their life stages, a vertical shift. [8]
Vertical shift could occur due to predation being higher close to the sea floor and/or warmer water having a larger abundance of plankton. Juvenile slickheads may have a preference to travel upwards to take advantage of the lack of predation and abundance of food to increase survival rates. [9]
The species of Alepocephalidae are widely distributed throughout the world and can be found in the Atlantic, Indian, and western Pacific oceans, [10] although they are difficult to find as they typically live around the bathypelagic layer of the ocean.
Sparidae is a family of ray-finned fishes belonging to the order Spariformes, the sea breams and porgies, although they were traditionally classified in the order Perciformes. They are found in shallow temperate and tropical waters around the world and are demersal carnivores.
The Osmeriformes are an order of ray-finned fish that includes the true or freshwater smelts and allies, such as the galaxiids and noodlefishes; they are also collectively called osmeriforms. They belong to the teleost superorder Protacanthopterygii, which also includes pike and salmon, among others. The order's name means "smelt-shaped", from Osmerus + the standard fish order suffix "-formes". It ultimately derives from Ancient Greek osmé + Latin forma, the former in reference to the characteristic aroma of the flesh of Osmerus.
The snailfishes or sea snails are a family of marine ray-finned fishes. These fishes make up the Liparidae, which is classified within the order Scorpaeniformes.
Lanternfish are small mesopelagic fish of the large family Myctophidae. One of two families in the order Myctophiformes, the Myctophidae are represented by 246 species in 33 genera, and are found in oceans worldwide. Lanternfishes are aptly named after their conspicuous use of bioluminescence. Their sister family, the Neoscopelidae, are much fewer in number but superficially very similar; at least one neoscopelid shares the common name "lanternfish": the large-scaled lantern fish, Neoscopelus macrolepidotus.
Lancetfishes are large oceanic predatory fishes in the genus Alepisaurus in the monogeneric family Alepisauridae.
Barreleyes, also known as spook fish, are small deep-sea argentiniform fish comprising the family Opisthoproctidae found in tropical-to-temperate waters of the Atlantic, Pacific, and Indian Oceans.
Leiognathidae, the ponyfishes, slipmouths or slimys / slimies, are a small family of fishes in the order Perciformes. They inhabit marine and brackish waters in the Indian and West Pacific Oceans. They can be used in the preparation of bagoong.
Albulidae is a family of fish, commonly known as the bonefishes, that are popular as game fish in Florida, select locations in the South Pacific and the Bahamas and elsewhere. The family is small, with 11 species in 3 genera. Presently, the bonefishes are in their own order: Albuliformes. The families Halosauridae and Notacanthidae were previously classified in this order, but are now, according to FishBase, given their own order Notacanthiformes. The largest bonefish caught in the Western Hemisphere is a 16-pound, 3 ounce example caught off Islamorada, Florida, on March 19, 2007.
The Argentiniformes is an order of marine ray-finned fish whose distinctness was recognized only fairly recently. In former times, they were included in the Osmeriformes as suborder Argentinoidei. That term refers only to the suborder of marine smelts and barreleyes in the classification used here, with the slickheads and allies being the Alepocephaloidei. These suborders were treated as superfamilies Argentinoidea and Alepocephaloidea, respectively, when the present group was still included in the Osmeriformes.
Leptochilichthys is a genus of fishes containing four species. Leptochilichthys is the only genus in the former family Leptochilichthyidae but is now included within the broader family Alepocephalidae.
Genetypes is a taxonomic concept proposed in 2010 to describe any genetic sequences from type specimens. This nomenclature integrates molecular systematics and terms used in biological taxonomy. This nomenclature is designed to label, or flag, genetic sequences that were sampled from type specimens. The nomenclature of genetypes proposes that genetic sequences from a holotype should be referred to as a “hologenetype”, sequences from a topotype should be a “topogenetype”, and so forth. In addition, the genetic marker(s) used should be incorporated into the nomenclature.
Opisthoproctus soleatus is a species of fish in the family Opisthoproctidae. It was first described in 1888 by Léon Vaillant. The species lives in most tropical seas, but is more common in the eastern Atlantic, from western Ireland to Mauritania and from Sierra Leone to Angola, and also in the South China Sea. O. soleatus can grow to a standard length of 10.5 centimetres (4.1 in) and usually live from about 500 to 700 metres deep.
Leptoderma is a genus of slickheads found in the deep waters of the oceans.
Narcetes is a genus of slickheads. It was formally described by Alfred William Alcock in 1890. It currently contains six described species.
Alepocephaliformes is an order of marine deep-sea teleost fishes. It was previously classified as the suborder Alepocephaloidei of the order Argentiniformes.
Regalecus russelii, or Russell's oarfish, is a species of oarfish in the family Regalecidae. It is a broadly-distributed marine fish, found in waters in the bathypelagic zone. R. russelii is a scaleless, elongate and ribbonlike fish, growing up to 8 meters in length.
Argyropelecus olfersii is a common species of marine hatchetfish, found in mesopelagic waters.
Narcetes shonanmaruae, the yokozuna slickhead, is a species of marine ray-finned fish, a slickhead belonging to the family Alepocephalidae. It was first formally described in 2021, the description being based on four specimens which were collected below a depth of 2,171 m (7,123 ft) in Suruga Bay in Japan. Its largest verified size is 130 cm (51 in), however recent footage with a reference has given the fish a much larger estimated length of 253 cm (100 in), however unverified. The specific name references Shonan Maru, the ship the specimens were collected from. The proposed English name, yokozuna slickhead, refers to the highest ranking of sumo wrestler, the yokozuna.
Leptoderma ospesca, the eastern eel-slickhead, is a species of slickhead found in the eastern-central Pacific Ocean.
Leptoderma macrophthalmum is a species of slickhead found in the Atlantic Ocean.
{{cite book}}
: CS1 maint: multiple names: authors list (link)