Gasterosteiformes
Encyclopedia
Gasterosteiformes is an order
of ray-finned fishes that includes the stickleback
s and relatives.
In the Gasterosteiformes, the pelvic girdle
is never attached to the cleithra directly, and the supramaxillary, orbitosphenoid, and basisphenoid bones are absent. The body is often partly or completely covered with dermal plates.
The name "Gasterosteiformes" means "bone-bellies". It is derived from Ancient Greek
gaster (γαστήρ; "stomach", "abdomen") + ostoun (ὀστοῦν; "bone"). The ending for fish orders "-formes" is derived from Latin
and indicates "of similar form".
es and their relatives as suborder Syngnathoidei, with the sticklebacks and relatives in the suborder Gasterosteoidei. In many more recent treatments the traditional placement as different orders, with the former becoming Syngnathiformes
, is used. There is a growing body of evidence that this is correct; in fact, the two groups do not seem to be particularly close relatives among the Acanthopterygii
.
As it seems, the loosely delimited Gasterosteiformes are paraphyletic with the Scorpaeniformes
. The more typical members of that group (e.g. scorpionfish
es) are apparently closer to the "true" Gasterosteiformes, whereas the keel-bodied flying gurnards (Dactylopteridae) seem actually to belong to the Syngnathiformes clade
. It seems that the closest living relatives of the narrowly-delimited Gasterosteiformes are the gunnel
s (Pholidae) and eelpout
s (Zoarcidae), traditionally placed in the massively paraphyletic "Perciformes
". These two families, as well as the related Trichodontidae
, would then appear to be derived offshoots of the scorpaeniform-gasterosteiform radiation
which have apomorphically lost the bone "armour" found in their relatives.
Three families
certainly belong to the Gasterosteiformes sensu stricto:
The armoured sticklebacks (Indostomidae) and the dragonfishes and sea moths (Pegasidae
) are variously placed with the pipefish or the stickleback lineage. While the Pegasidae are almost certainly Syngnathiformes, the placement of the monotypic
former family is essentially unresolved, as it has always been. Following the practice of the major fish classification organizations, it is included here.
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 fishes that includes the stickleback
Stickleback
The Gasterosteidae are a family of fish including the sticklebacks. FishBase currently recognises sixteen species in the family, grouped in five genera. However several of the species have a number of recognised subspecies, and the taxonomy of the family is thought to be in need of revision...
s and relatives.
In the Gasterosteiformes, the pelvic girdle
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
is never attached to the cleithra directly, and the supramaxillary, orbitosphenoid, and basisphenoid bones are absent. The body is often partly or completely covered with dermal plates.
The name "Gasterosteiformes" means "bone-bellies". It is derived 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...
gaster (γαστήρ; "stomach", "abdomen") + ostoun (ὀστοῦν; "bone"). The ending for fish orders "-formes" is derived from 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...
and indicates "of similar form".
Systematics
Often Gasterosteiformes includes the sea horses, pipefishPipefish
Pipefishes or pipe-fishes are a subfamily of small fishes, which, together with the seahorses, form the family Syngnathidae.-Anatomy:...
es and their relatives as suborder Syngnathoidei, with the sticklebacks and relatives in the suborder Gasterosteoidei. In many more recent treatments the traditional placement as different orders, with the former becoming Syngnathiformes
Syngnathiformes
Syngnathiformes is an order of ray-finned fishes that includes the pipefishes and seahorses.These fishes have elongate, narrow, bodies surrounded by a series of bony rings, and small, tubular mouths. Several groups live among seaweed and swim with the body aligned vertically, to blend in with the...
, is used. There is a growing body of evidence that this is correct; in fact, the two groups do not seem to be particularly close relatives among the Acanthopterygii
Acanthopterygii
Acanthopterygii is a superorder of bony fishes in the class Actinopterygii. Members of this superorder are also known as the ray-finned fishes for the characteristic sharp, bony rays in their fins; however this name is also often given to the class Actinopterygii as a whole.Orders:* Order...
.
As it seems, the loosely delimited Gasterosteiformes are paraphyletic with the Scorpaeniformes
Scorpaeniformes
Scorpaeniformes is an order of ray-finned fish, but it has also been called the Scleroparei.They are known as "mail-cheeked" fishes due to their distinguishing characteristic, the suborbital stay: a backwards extension of the third circumorbital bone across the cheek to the preoperculum, to which...
. The more typical members of that group (e.g. scorpionfish
Scorpionfish
Scorpaenidae, the scorpionfish, are a family of mostly marine fish that includes many of the world's most venomous species. As the name suggests, scorpionfish have a type of "sting" in the form of sharp spines coated with venomous mucus. The family is a large one, with hundreds of members. They are...
es) are apparently closer to the "true" Gasterosteiformes, whereas the keel-bodied flying gurnards (Dactylopteridae) seem actually to belong to the Syngnathiformes clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
. It seems that the closest living relatives of the narrowly-delimited Gasterosteiformes are the gunnel
Pholidae
The gunnels are a family, Pholidae, of fishes in the order Perciformes.They are elongated fishes native to the coasts of the northern Atlantic, Pacific and Arctic Oceans, where they inhabit intertidal and subtidal waters and eat crustaceans and molluscs.-Species:There are fifteen species in three...
s (Pholidae) and eelpout
Eelpout
The eelpouts are the ray-finned fish family Zoarcidae. As the common name suggests, they are somewhat eel-like in appearance, with elongate bodies, and the dorsal and anal fins continuous with the caudal fin. All of the approximately 220 species are marine, mostly bottom-dwelling, some at great...
s (Zoarcidae), traditionally placed in the massively paraphyletic "Perciformes
Perciformes
The Perciformes, also called the Percomorphi or Acanthopteri, is one of the largest orders of vertebrates, containing about 40% of all bony fish. Perciformes means perch-like. They belong to the class of ray-finned fish and comprise over 7,000 species found in almost all aquatic environments...
". These two families, as well as the related Trichodontidae
Trichodontidae
The Trichodontidae, or sandfishes are a small perciform family of fishes that occur in the North Pacific. The family consists of two monotypic genera:* Arctoscopus Jordan and Evermann, 1896...
, would then appear to be derived offshoots of the scorpaeniform-gasterosteiform radiation
Evolutionary radiation
An evolutionary radiation is an increase in taxonomic diversity or morphological disparity, due to adaptive change or the opening of ecospace. Radiations may affect one clade or many, and be rapid or gradual; where they are rapid, and driven by a single lineage's adaptation to their environment,...
which have apomorphically lost the bone "armour" found in their relatives.
Three 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...
certainly belong to the Gasterosteiformes sensu stricto:
- Aulorhynchidae – tube-snouts
- Gasterosteidae – sticklebacks
- Hypoptychidae – the Sand Eel
- Indostomidae – armoured sticklebacks
The armoured sticklebacks (Indostomidae) and the dragonfishes and sea moths (Pegasidae
Pegasidae
The seamoths are a family, the Pegasidae, of fish found in coastal tropical waters.They are distinguished by flattened bodies, the presence of large, wing-like, pectoral fins, and a body encased in thick, bony plates. Most species also have an elongated snout in front of their jaws...
) are variously placed with the pipefish or the stickleback lineage. While the Pegasidae are almost certainly Syngnathiformes, the placement of the 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...
former family is essentially unresolved, as it has always been. Following the practice of the major fish classification organizations, it is included here.
External links
- Gasterosteiformes entry on Animal Diversity Web