Osmeriformes is an
orderIn 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 that includes the
true or freshwater smelts and allies, such as the
galaxiidThe Galaxiids are a family of mostly small freshwater fish. Representatives occur throughout the southern hemisphere, including South Africa, South America, New Zealand, Australia, Lord Howe Island, New Caledonia and the Falkland Islands. One species of galaxiid, Galaxias maculatus, is probably...
s and noodlefishes; they are also collectively called
osmeriforms. They belong to the teleost superorder
ProtacanthopterygiiProtacanthopterygii is a ray-finned fish taxon ranked as a superorder of the infraclass Teleostei. They inhabit both marine and freshwater habitat...
, which also includes
pikePike may refer to:-Fish:*Pike or Esox*Blue pike or blue walleye, an extinct freshwater fish*Mackerel pike or Pacific saury, a fish popular in east Asian cuisine*Northern pike, known as the "pike" in Britain-Places:In Britain:...
and
salmonSalmon is the common name for several species of fish of the family Salmonidae. Several other fish in the family are called trout; the difference is often attributed to the migratory life of the salmon as compared to the residential behaviour of trout, a distinction that holds true for the Salmo...
, among others. The order's name means "smelt-shaped", from
OsmerusOsmerus is a genus of fish in the Osmeridae family.It contains the following species:* Pygmy smelt * Rainbow smelt * European smelt...
(the
type genusIn biology, the phrase type genus is used differently depending on the nomenclatural Code that applies:* In zoological nomenclature, a type genus is "The nominal genus that is the name-bearing type of a nominal family-group taxon."...
) + the standard
fishA fish is any aquatic vertebrate animal that is typically ectothermic , covered with scales, and equipped with two sets of paired fins and several unpaired fins...
order
suffixIn grammar, 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".
Osmeriformes is an
orderIn 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 that includes the
true or freshwater smelts and allies, such as the
galaxiidThe Galaxiids are a family of mostly small freshwater fish. Representatives occur throughout the southern hemisphere, including South Africa, South America, New Zealand, Australia, Lord Howe Island, New Caledonia and the Falkland Islands. One species of galaxiid, Galaxias maculatus, is probably...
s and noodlefishes; they are also collectively called
osmeriforms. They belong to the teleost superorder
ProtacanthopterygiiProtacanthopterygii is a ray-finned fish taxon ranked as a superorder of the infraclass Teleostei. They inhabit both marine and freshwater habitat...
, which also includes
pikePike may refer to:-Fish:*Pike or Esox*Blue pike or blue walleye, an extinct freshwater fish*Mackerel pike or Pacific saury, a fish popular in east Asian cuisine*Northern pike, known as the "pike" in Britain-Places:In Britain:...
and
salmonSalmon is the common name for several species of fish of the family Salmonidae. Several other fish in the family are called trout; the difference is often attributed to the migratory life of the salmon as compared to the residential behaviour of trout, a distinction that holds true for the Salmo...
, among others. The order's name means "smelt-shaped", from
OsmerusOsmerus is a genus of fish in the Osmeridae family.It contains the following species:* Pygmy smelt * Rainbow smelt * European smelt...
(the
type genusIn biology, the phrase type genus is used differently depending on the nomenclatural Code that applies:* In zoological nomenclature, a type genus is "The nominal genus that is the name-bearing type of a nominal family-group taxon."...
) + the standard
fishA fish is any aquatic vertebrate animal that is typically ectothermic , covered with scales, and equipped with two sets of paired fins and several unpaired fins...
order
suffixIn grammar, 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 GreekAncient Greek is the historical stage in the development of the Greek language spanning across the Archaic , Classical , and Hellenistic periods of ancient Greece and the ancient world. It is predated in the 2nd millennium BC by Mycenaean Greek...
osmé (ὀσμή, "pungent smell") +
LatinLatin is an Italic language originally spoken in Latium and Ancient Rome. Through the Roman conquest, Latin spread throughout the Mediterranean and a large part of Europe...
forma ("external form"), the former in reference to the characteristic aroma of the flesh of
Osmerus.
In the classification used here, the order Osmeriformes contains 2 suborders, 6
familiesIn 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...
, some 20 genera and about 90
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
. Other authors choose a slightly different arrangement, but whether treated as suborders (Galaxoidei and Osmeroidei) or superfamilies (Galaxoidea and Osmeroidea), the division in two lineages is generally maintained.
The "marine" smelts and allies (e.g. the odd-looking
barreleyeBarreleyes, also known as spookfish , are small, unusual-looking deep-sea osmeriform fish comprising the family Opisthoproctidae...
s) were formerly included here as suborder Argentinoidei; they are now usually considered more distantly related than it was believed and treated as order
ArgentiniformesArgentiniformes is an order of ray-finned fish whose distinctness was reconized 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...
. When the marine smelts were included here, the subdivisions of the Osmeriformes were down-
rankedIn biological classification, rank is the level in a taxonomic hierarchy. The most basic rank is that of species, the next most important is genus, and then family...
by one.
Description and ecology
Osmeriformes are small to mid-sized slender fish. Their
maxillaThe maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes , the maxilla is sometimes called "upper maxilla", with the mandible being the "lower maxilla"...
is usually included in the mouth's gape, and most of them have an adipose fin as is often found in the
ProtacanthopterygiiProtacanthopterygii is a ray-finned fish taxon ranked as a superorder of the infraclass Teleostei. They inhabit both marine and freshwater habitat...
. Their pterosphenoid usually has a ventral flange, and the
vomerThe vomer is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones.-Biology:...
has a short posterior shaft. They have reduced or even missing articular and mesopterygoid teeth, and the basisphenoid and orbitosphenoid bones are entirely absent. Their
scaleIn most biological nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration...
s lack radii.
Despite the term "
freshwaterFreshwater is naturally occurring water on the surface such as bogs, ponds, lakes, rivers and streams, and underground in aquifers and underground rivers. Freshwater is characterized by having low concentrations of dissolved salts...
smelts", the members of the Osmeriformes are generally
marineMarine or Marines may refer to:*Marine , a general term for things relating to the sea or ocean*Marine , a member of the military in an infantry or amphibious force under the authority of a navy, or in several cases, of an independent amphibious force **The military rank of "Marine", being the...
, or amphidromous or anadromous migrants. Even the sedentary freshwater species in this family are usually tolerant of considerable changes in
salinitySalinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
. Almost all osmeriforms
spawnSpawning is the production or depositing of large quantities of eggs in water. The process is done by aquatic animals such as amphibians and fish.- Types of egg-layers :*egg scatterers*nest builders*egg hangers*mouth breeders*egg buriers...
in fresh water, thus the marine species are generally anadromous. They are found in
temperateIn geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally mild, rather than extreme hot or cold. But in continental areas, such as central North America the variations between summer...
oceans worldwide and in temperate
freshwaterFreshwater is naturally occurring water on the surface such as bogs, ponds, lakes, rivers and streams, and underground in aquifers and underground rivers. Freshwater is characterized by having low concentrations of dissolved salts...
of the
HolarcticThe Holarctic ecozone refers to the habitats found throughout the northern continents of the world as a whole. This region is divided into the Palearctic, consisting of Northern Africa and all of Eurasia, with the exception of Southeast Asia and the Indian subcontinent, and the Nearctic,...
and around the
South PacificOceania is a geographical, often geopolitical, region consisting of numerous lands—mostly islands in the Pacific Ocean and vicinity. The term "Oceania" was coined in 1831 by French explorer Dumont d'Urville...
region; only a handful of
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
occur in tropical waters. The
egg-Foods:*Egg , usually chicken eggs, but also those of other birds and turtles, as well as those of fish-Geography:*Egg Island *Egg, Switzerland, a Swiss municipality*Egg an der Günz, a municipality in Bavaria, Germany*Egg, Austria...
s are surrounded by an adhesive
membraneA membrane is a layer of material which serves as a selective barrier between two phases and remains impermeable to specific particles, molecules, or substances when exposed to the action of a driving force...
.
Systematics
With the
ArgentiniformesArgentiniformes is an order of ray-finned fish whose distinctness was reconized 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...
separated as a distinct order, the remaining Osmeriformes appear to be a monophyletic group. Their placement in the Protacanthopterygii is not entirely clear, but may well be the closest living relatives of the
EsociformesEsociformes is a small order of ray-finned fish, with two families, the Umbridae and the Esocidae . The pikes of genus Esox give the order its name. There are ten species--five in each family....
(
pikePike may refer to:-Fish:*Pike or Esox*Blue pike or blue walleye, an extinct freshwater fish*Mackerel pike or Pacific saury, a fish popular in east Asian cuisine*Northern pike, known as the "pike" in Britain-Places:In Britain:...
s and mudminnows). Others consider them closer to the Salmoniformes (
troutTrout are a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the Salmonidae family. Salmon belong to some of the same genera as trout but, unlike most trout, most salmon species spend almost all their lives in salt water...
s,
salmonSalmon is the common name for several species of fish of the family Salmonidae. Several other fish in the family are called trout; the difference is often attributed to the migratory life of the salmon as compared to the residential behaviour of trout, a distinction that holds true for the Salmo...
s and relatives). A closer relationship to the
StomiiformesStomiiformes is an order of deep-sea ray-finned fishes of very diverse morphology. It includes for example dragonfishes, lightfishes, loosejaws, marine hatchetfishes and viperfishes. The order contains 4 families with more than 50 genera and almost 400 species...
than previously assumed is supported by anatomical and
DNA sequenceA DNA sequence or genetic sequence is a succession of letters representing the primary structure of a real or hypothetical DNA molecule or strand, with the capacity to carry information as described by the central dogma of molecular biology....
data. But this can be simply taken to suggest that the superorder "
StenopterygiiStenopterygii are a superorder of ray-finned fish in the infraclass Teleostei. Their validity is somewhat doubtful, as the group was established to unite not more than two rather peculiarly autapomorphic orders at best. In some treatments, it is even monotypic.As originally conceived, the...
" ought to be included in the Protacanthopterygii, rather than a particularly close relationship between the two orders.
The classification of the Osmeriformes as approached here is:
- Suborder Galaxoidei
- Family Galaxiidae – galaxiid
- Family Lepidogalaxiidae – West Australian Salamanderfish
- Family Retropinnidae
Retropinnidae is a family of bony fish that contains the southern hemisphere smelts and graylings. They are quite closely related to the northern smelts , which they greatly resemble, but not to the northern graylings . Species from this family are only found in southeastern Australia and New Zealand...
– Austalian-New Zealand smelts and graylings
- Suborder Osmeroidei
- Family Osmeridae – freshwater smelts, typical smelts
- Family Plecoglossidae – Ayu
- Family Salangidae
Icefishes or noodlefishes are a family, the Salangidae, of osmeriform fish, related to the smelts. They are found in freshwater environments in Southeast Asia, although a few species are anadromous, spending most of their life in coastal waters, and only visiting fresh water to spawn.They have...
– noodlefishes, "icefishes"
A possible
fossilFossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous rock formations and sedimentary layers is known as the fossil record...
osmeriform is
Spaniodon, a
piscivoreA piscivore is a carnivorous animal which lives on eating fish.Some animals, like the sea lion, or alligator, are not completely piscivores, while others, like the Aquatic Genet, are strictly dependent on fish for food...
from
Late CretaceousThe Late Cretaceous is the youngest of two epochs in which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
seas. The group originated probably somewhat earlier, but a
CretaceousThe Cretaceous , Latin language for "chalky", usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago . In the geologic timescale, the Cretaceous follows on the Jurassic period and is followed by the Paleogene period of the...
age – maybe about 110 million years ago or so – is likely.