ray-finned fish
Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species.
The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...
families
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideal ...
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
. The common names grinners, lizardfishes and allies, or aulopiforms are sometimes used for this group. The scientific name means "''Aulopus''-shaped", from ''
Aulopus
''Aulopus'' is a genus of flagfins native to the Atlantic Ocean and the Pacific Ocean. Although ''Aulopus'' is native to both the Atlantic and the Pacific oceans, for the first time in 2010 ''Aulopus filamentosus'' (the royal flagfin), was spott ...
'' (the
type genus
In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name.
Zoological nomenclature
According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal ...
) + the standard
fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...
order suffix "-formes". It ultimately derives from
Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...
''aulós'' (αὐλός, "flute" or "pipe") +
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
''forma'' ("external form"), the former in reference to the elongated shape of many aulopiforms.FishBase (2000)
They are grouped together because of common features in the structure of their
gill arch
Branchial arches, or gill arches, are a series of bony "loops" present in fish, which support the gills. As gills are the primitive condition of vertebrates, all vertebrate embryos develop pharyngeal arches, though the eventual fate of these arc ...
es. Indeed, many authors have considered them so distinct as to warrant separation in a
monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...
Teleostei
Teleostei (; Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts ), is, by far, the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Te ...
, under the name Cyclosquamata. However, monotypic taxa are generally avoided by modern
taxonomist
In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are give ...
s if not necessary, and in this case a distinct superorder seems indeed unwarranted: together with the equally dubious superorder " Stenopterygii", the grinners appear to be so closely related to some
Protacanthopterygii
Protacanthopterygii is a ray-finned fish taxon ranked as a superorder of the infraclass Teleostei. They inhabit both marine and freshwater habitats. They appear to have evolved in the Cretaceous or perhaps late Jurassic, originating probably roug ...
to be included in that superorder. In particular, this group might be the
sister taxon
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and ...
of the
Salmoniformes
Salmonidae is a family of ray-finned fish that constitutes the only currently extant family in the order Salmoniformes . It includes salmon (both Atlantic and Pacific species), trout (both ocean-going and landlocked), chars, freshwater whitefis ...
(salmon, trout, and relatives). As an alternative, the superorders are sometimes united as an unranked clade named Euteleostei, but in that case the Protacanthopterygii would need to be split further to account for the
phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
uncertainty. This would result in a highly cumbersome and taxonomically redundant group of two very small and no less than four monotypic superorders.
Description
Many aulopiforms are
deep-sea
The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of 200 metres (656 feet) or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combin ...
fishes, with some
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
recognized as being hermaphrodites, some with the ability to self-fertilise. Some are benthic, but most are
pelagic
The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...
nekton
Nekton or necton (from the ) refers to the actively swimming aquatic organisms in a body of water. The term was proposed by German biologist Ernst Haeckel to differentiate between the active swimmers in a body of water, and the passive organisms t ...
. In general, aulopiform fish have a mixture of advanced and primitive characteristics relative to other
teleost
Teleostei (; Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts ), is, by far, the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Tele ...
fish.
Aulopiforms have either a vestigial gas bladder, or lack it entirely, a hypaxialis muscle that is unusually extended to forward at its upper end and attaches to the
neurocranium
In human anatomy, the neurocranium, also known as the braincase, brainpan, or brain-pan is the upper and back part of the skull, which forms a protective case around the brain. In the human skull, the neurocranium includes the calvaria or skul ...
below the spine (perhaps to snap the upper part of the skull down when catching prey) and the position of the
maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...
ry bone. Their second
pharyngobranchial
Branchial arches, or gill arches, are a series of bony "loops" present in fish, which support the gills. As gills are the primitive condition of vertebrates, all vertebrate embryos develop pharyngeal arches, though the eventual fate of these arc ...
is greatly elongated posterolaterally away from third pharyngobranchial, which lacks a
cartilaginous
Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck a ...
pelvic girdle
The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton).
The p ...
, and the presence of an
adipose fin
Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...
(which is also typical for the Protacanthopterygii).
The
larva
A larva (; plural larvae ) 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.
...
e of some Aulopiformes are extremely bizarre-looking, with elongated fins, and do not resemble the adult animals. They were not only described as distinct species, but also even separated as genera and finally in a
family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
"Macristiidae" which was allied with various Protacanthopterygii (''
sensu lato
''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular c ...
''), but the initial assessment – which found ''"Macristium"'' to resemble the deepwater lizardfishes (Bathysauridae) in some details – was not far off the mark: "''Macristium''" species are larvae of '' Bathysaurus'', while the supposed other "macristiids", "''Macristiella''" species are larvae of the deepsea tripodfish ''
Bathytyphlops
''Bathytyphlops'' is a genus of deepsea tripod fishes known only from the eastern Atlantic Ocean.
Species
There are currently two recognized species in this genus:
* '' Bathytyphlops marionae'' Mead
Mead () is an alcoholic beverage made by ...
Evermannellidae
Sabertooth or sabretooth fish are small, fierce-looking deep-sea aulopiform fish comprising the family Evermannellidae. The family is small, with just eight species in three genera represented; they are distributed throughout tropical to subtropi ...
– sabertooth fishes
** Family Omosudidae – hammerjaw (sometimes included in Alepisauridae)
** Family Paralepididae – barracudinas
** Family † Polymerichthyidae – an extinct alepisauroid closely related to the daggertooths and lancetfishUyeno, Teruya. "A Miocene alepisauroid fish of a new family, Polymerichthyidae, from Japan." Bull. Nat. Sci. Mus 10 (1967): 383-394.
** Family Scopelarchidae – pearleyes
* Suborder Chlorophthalmoidei
** Family Bathysauroididae – pale deepsea lizardfish
** Family Bathysauropsidae – lizard greeneyes (sometimes included in Ipnopidae)
** Family
Chlorophthalmidae
Greeneyes are deep-sea Aulopiformes, aulopiform marine fishes in the small family Chlorophthalmidae. Thought to have a circumglobal distribution in tropical and temperate waters, the family contains just 18 species in two genera. The family name ...
– greeneyes
** Family Ipnopidae – deepsea tripodfishes
** Family Notosudidae – waryfishes
* Suborder Enchodontoidei (including Halecoidei, Ichthyotringoidei, may belong in Alepisauroidei;
fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
Halecidae
Halecidae is an extinct family of aulopiform fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well ...
(fossil)
** Family
Ichthyotringidae
Ichthyotringidae is an extinct family of aulopiform fish known from the Early to Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock st ...
Bathysauridae
The Bathysauridae are a small family of deepwater aulopiform fish, related to the telescopefishes. The two species in the family both belong to the genus ''Bathysaurus''. Commonly called deepwater lizardfishes or deepsea lizardfishes, the latter ...
– deepwater lizardfishes
** Family Giganturidae – telescopefishes
* Suborder Synodontoidei
** Family
Aulopidae
The Aulopidae are a small family of aulopiform fish. They are found in most tropical and subtropical oceans, and are commonly known as flagfins.
The aulopids resemble lizardfishes in appearance, and range up to in length. They have large dorsal ...
– flagfins
** Family Paraulopidae – "cucumberfishes"
** Family
Pseudotrichonotidae
''Pseudotrichonotus'' is a genus of fish in the family Pseudotrichonotidae native to the Indian Ocean, Indian and Pacific Ocean. This genus is the only member of its family (biology), family.
Species
There are currently 4 recognized species in t ...
Late
Late may refer to:
* LATE, an acronym which could stand for:
** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia
** Local-authority trading enterprise, a New Zealand business law
** Local average treatment effect, ...
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
Aulopus
''Aulopus'' is a genus of flagfins native to the Atlantic Ocean and the Pacific Ocean. Although ''Aulopus'' is native to both the Atlantic and the Pacific oceans, for the first time in 2010 ''Aulopus filamentosus'' (the royal flagfin), was spott ...
Scopelosaurus
''Scopelosaurus'' is a genus of waryfishes.
The generic name is from the Greek words σκόπελος (''skopelos'', "lanternfish") and σαῦρος (''sauros'', "Atlantic horse mackerel, horse mackerel").
Species
There are currently 14 recogn ...
Late
Late may refer to:
* LATE, an acronym which could stand for:
** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia
** Local-authority trading enterprise, a New Zealand business law
** Local average treatment effect, ...
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...