Myctophiformes
Encyclopedia
Myctophiformes is an order
of ray-finned fish consisting of two families
of deep-sea marine
fish, most notably the highly abundant lanternfish
es (Myctophidae). The blackchins (Neoscopelidae) contain a handful of species
in three genera
, while the bulk of the family belongs to the Myctophidae, with over 30 genera and almost 250 species.
The scientific name means "Ateleopus-shaped", from Ateleopus
(the type genus
) + the standard fish
order suffix
"-formes". It ultimately derives from Ancient Greek
myktér (μυκτήρ, "nose") + óphis (ὄφῖς, "serpent") + Latin
forma ("external form"), the Greek part in reference to the long, slender and heavy-headed shape of these fishes.
. They are laterally compressed and usually have photophore
s (light organs). The eyes are large, in some decidedly huge, and generally directed straight sideways. The mouth also quite large and located at the tip of the snout; its gape extends to below the eyes or even beyond. They have an adipose fin. The pelvic fin has 8 rays in most myctophiforms, and the number of branchiostegal rays is usually higher than 6 and lower than a dozen.
of the Myctophiformes are:
The order
Myctophiformes is anatomically similar to the grinners (Aulopiformes), but their pharyngobranchials and retractor muscles are more plesiomorphic. It was also allied with the more advanced spiny-rayed Teleostei
(e.g. Paracanthopterygii
) as "Ctenosquamata". These apomorphically have a fifth upper pharyngeal toothplate and a third internal levator muscle
to move it, and molecular
data also supports the long-held view that these two lineages are at least closely related. Other sources ally them with the Lampriformes
, which are often placed in a monotypic
superorder "Lampridiomorpha". In a similar fashion, separation of the Myctophiformes in superorder "Scopelomorpha" has been proposed. The Aulopiformes, meanwhile, are usually considered to be closer or even among the Protacanthopterygii
, one of the core groups of moderately advanced teleosts. As modern taxonomy
tries to avoid a profusion of small taxa, and the delimitation of the Euteleostei (Protacanthopterygii sensu stricto and their allies) versus "Ctenosquamata" such as the Paracanthopterygii
remains uncertain, the systematics
and taxonomy of the Myctophiformes among the teleosts are in need of further study.
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
of ray-finned fish consisting of two families
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of deep-sea marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
fish, most notably the highly abundant lanternfish
Lanternfish
Cooper Lanternfishes 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. They are aptly named after their conspicuous use of bioluminescence...
es (Myctophidae). The blackchins (Neoscopelidae) contain a handful of species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
in three genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
, while the bulk of the family belongs to the Myctophidae, with over 30 genera and almost 250 species.
The scientific name means "Ateleopus-shaped", from Ateleopus
Ateleopus
Ateleopus is a genus of ray-finned fish in the jellynose family . It is the type genus of its family, and the order Ateleopodiformes. For some time, it was known as Podateles, because Ateleopus had been used to replace the frog genus name Atelopus, which was deemed to be a spelling error...
(the type genus
Type genus
In biological classification, a type genus is a representative genus, as with regard to a biological family. The term and concept is used much more often and much more formally in zoology than it is in botany, and the definition is dependent on the nomenclatural Code that applies:* In zoological...
) + the standard fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate 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...
order suffix
Suffix
In linguistics, a suffix is an affix which is placed after the stem of a word. Common examples are case endings, which indicate the grammatical case of nouns or adjectives, and verb endings, which form the conjugation of verbs...
"-formes". It ultimately derives from Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
myktér (μυκτήρ, "nose") + óphis (ὄφῖς, "serpent") + Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
forma ("external form"), the Greek part in reference to the long, slender and heavy-headed shape of these fishes.
Description and ecology
These smallish fishes inhabit the pelagic and benthopelagic zones of the deep seaDeep sea
The deep sea, or deep layer, is the lowest layer in the ocean, existing below the thermocline and above the seabed, at a depth of 1000 fathoms or more. Little or no light penetrates this part of the ocean and most of the organisms that live there rely for subsistence on falling organic matter...
. They are laterally compressed and usually have photophore
Photophore
A photophore is a light-emitting organ which appears as luminous spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye; equipped with lenses, shutters, color filters and reflectors...
s (light organs). The eyes are large, in some decidedly huge, and generally directed straight sideways. The mouth also quite large and located at the tip of the snout; its gape extends to below the eyes or even beyond. They have an adipose fin. The pelvic fin has 8 rays in most myctophiforms, and the number of branchiostegal rays is usually higher than 6 and lower than a dozen.
Systematics
The two familiesFamily (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of the Myctophiformes are:
- Myctophidae – lanternfishes
- NeoscopelidaeNeoscopelidaeThe Neoscopelidae are a small family of deep sea fish closely related to the lanternfish. They are found in tropical and subtropical marine waters worldwide....
– blackchins
The order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Myctophiformes is anatomically similar to the grinners (Aulopiformes), but their pharyngobranchials and retractor muscles are more plesiomorphic. It was also allied with the more advanced spiny-rayed Teleostei
Teleostei
Teleostei is one of three infraclasses in class Actinopterygii, the ray-finned fishes. This diverse group, which arose in the Triassic period, includes 20,000 extant species in about 40 orders; most living fishes are members of this group...
(e.g. Paracanthopterygii
Paracanthopterygii
Paracanthopterygii is a superorder of fishes. Members of this superorder are called paracanthopterygians.It includes five orders:* Percopsiformes * Batrachoidiformes * Lophiiformes...
) as "Ctenosquamata". These apomorphically have a fifth upper pharyngeal toothplate and a third internal levator muscle
Levator muscle
Levator muscle can refer to:* Levator scapulae muscle* Levator palpebrae superioris muscle* Levator ani* Levator labii superioris alaeque nasi muscle* Levator veli palatini* Levator muscle of thyroid gland* Levator labii superioris* Levator anguli oris...
to move it, and molecular
Molecular phylogeny
Molecular phylogenetics is the analysis of hereditary molecular differences, mainly in DNA sequences, to gain information on an organism's evolutionary relationships. The result of a molecular phylogenetic analysis is expressed in a phylogenetic tree...
data also supports the long-held view that these two lineages are at least closely related. Other sources ally them with the Lampriformes
Lampriformes
Lampriformes is an order of ray-finned fish. They are collectively called "lamprids" or lampriforms, and unite such open-ocean and partially deep-sea Teleostei as the crestfishes, oarfish, opahs and ribbonfishes...
, which are often placed in a monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
superorder "Lampridiomorpha". In a similar fashion, separation of the Myctophiformes in superorder "Scopelomorpha" has been proposed. The Aulopiformes, meanwhile, are usually considered to be closer or even among the Protacanthopterygii
Protacanthopterygii
Protacanthopterygii is a ray-finned fish taxon ranked as a superorder of the infraclass Teleostei. They inhabit both marine and freshwater habitat...
, one of the core groups of moderately advanced teleosts. As modern taxonomy
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
tries to avoid a profusion of small taxa, and the delimitation of the Euteleostei (Protacanthopterygii sensu stricto and their allies) versus "Ctenosquamata" such as the Paracanthopterygii
Paracanthopterygii
Paracanthopterygii is a superorder of fishes. Members of this superorder are called paracanthopterygians.It includes five orders:* Percopsiformes * Batrachoidiformes * Lophiiformes...
remains uncertain, the systematics
Systematics
Biological systematics is the study of the diversification of terrestrial life, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees...
and taxonomy of the Myctophiformes among the teleosts are in need of further study.